U.S. patent application number 12/670154 was filed with the patent office on 2010-07-29 for battery assembly manufacturing method.
Invention is credited to Satomi Kawase, Tomohiro Matsuura.
Application Number | 20100190049 12/670154 |
Document ID | / |
Family ID | 40281326 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100190049 |
Kind Code |
A1 |
Kawase; Satomi ; et
al. |
July 29, 2010 |
BATTERY ASSEMBLY MANUFACTURING METHOD
Abstract
A method for manufacturing a battery assembly provided by the
present invention includes a step of measuring a stacking direction
length of a stacked body including a predetermined number of unit
cells (12) constituting a battery assembly (10) and arranged in the
stacking direction; and a step of bundling a body (20) to be
bundled that includes the stacked body. Here, the body to be
bundled is provided with length adjusting means (40) for converging
a spread in stacking direction length. The bundling step is
implemented by setting the length adjusting means according to the
stacking direction length of the stacked body, so that a length of
the battery assembly in the stacking direction is a stipulated
length (LT) and a bundling pressure of the body to be bundled is a
stipulated pressure.
Inventors: |
Kawase; Satomi; (Aichi-ken,
JP) ; Matsuura; Tomohiro; (Aichi-ken, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
40281326 |
Appl. No.: |
12/670154 |
Filed: |
July 17, 2008 |
PCT Filed: |
July 17, 2008 |
PCT NO: |
PCT/JP2008/062958 |
371 Date: |
January 22, 2010 |
Current U.S.
Class: |
429/159 ;
29/623.1; 429/156 |
Current CPC
Class: |
H01M 10/0481 20130101;
H01M 10/0431 20130101; Y10T 29/49108 20150115; H01M 50/20 20210101;
H01M 10/4285 20130101; H01M 10/0404 20130101; Y02E 60/10
20130101 |
Class at
Publication: |
429/159 ;
29/623.1; 429/156 |
International
Class: |
H01M 6/42 20060101
H01M006/42; H01M 4/82 20060101 H01M004/82 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2007 |
JP |
2007-191445 |
Claims
1-13. (canceled)
14. A method for manufacturing a battery assembly in which a
predetermined number of unit cells are arranged with a constant
stacking pitch in a stacking direction, comprising the steps of:
constructing a plurality of unit cells of the same shape, each unit
cell including an electrode body in which a positive electrode
sheet and a negative electrode sheet are laminated together with a
separator sheet, a container that accommodates the electrode body
and an electrolyte, and a positive electrode terminal and a
negative electrode terminal that are electrically connected to the
positive electrode and the negative electrode and are disposed
outside the container; forming a body to be bundled that includes
the predetermined number of unit cells arranged in the stacking
direction; and bundling the body to be bundled so that a length of
the battery assembly in the stacking direction is a stipulated
length LT and a bundling pressure of the body to be bundled is a
stipulated pressure P, wherein the step of constructing the
plurality of unit cells includes a processing in which a lamination
direction thickness of an electrode body of a standard
configuration that is predicted from the sheet thickness of the
positive electrode sheet, negative electrode sheet, and separator
sheet to be used to form the electrode body is compared with a
stipulated electrode body thickness E, and the electrode body is
formed to match the stipulated electrode body thickness E by
increasing or decreasing the amount of the separator sheet used
with respect to the standard configuration.
15. The battery assembly manufacturing method according to claim
14, wherein the electrode body is a wound electrode body in which
the laminated sheets are wound; the electrode body of the standard
configuration has a configuration in which only the separator sheet
is extra wound at the winding end of the electrode body; and the
electrode body is formed to match the stipulated electrode body
thickness E by increasing or decreasing the number of winding turns
of the separator sheet at the winding end.
16. The battery assembly manufacturing method according to claim
14, wherein the electrode body is formed by selecting one, or two
or more of positive electrode sheets, negative electrode sheets,
and separator sheets to be used to form the electrode bodies from a
plurality of positive electrode sheets, a plurality of negative
electrode sheets, and a plurality of separator sheets that have
been classified into a plurality of thickness ranks based on the
sheet thickness, and by using the selected positive electrode
sheets, negative electrode sheets, and separator sheets; and the
sheets to be used to form the electrode bodies are selected from
one, or two or more thickness ranks from among the plurality of
thickness ranks, so that the sum total of representative values of
the thickness ranks to which these sheets belong is a stipulated
thickness ST.
17. The battery assembly manufacturing method according to claim
14, wherein the body to be bundled is formed by: measuring the
stacking direction thickness for each of the plurality of unit
cells; classifying the plurality of unit cells into a plurality of
thickness ranks with mutually different thickness ranges based on
the stacking direction thickness; and selecting a predetermined
number of unit cells from one, or two or more thickness ranks from
among the plurality of thickness ranks so that a sum total of
representative values of thickness ranks to which the unit cells
belong is a stipulated length RT, the body to be bundled including
the selected unit cells arranged in the stacking direction.
18. The battery assembly manufacturing method according to claim
14, further comprising a step of measuring a stacking direction
length L1 of the stacked body, wherein the body to be bundled
includes length adjusting means for converging a spread in stacking
direction length L1, and the bundling step is implemented by
setting the length adjusting means according to the stacking
direction length L1.
19. A battery assembly in which a predetermined number of unit
cells are arranged with a constant stacking pitch in a stacking
direction, each unit cell including an electrode body in which a
positive electrode sheet and a negative electrode sheet are
laminated together with a separator sheet, a container that
accommodates the electrode body and an electrolyte, and a positive
electrode terminal and a negative electrode terminal that are
electrically connected to the positive electrode and the negative
electrode and are disposed outside the container, wherein a body to
be bundled that includes the predetermined number of unit cells
arranged in the stacking direction is bundled so that a length of
the battery assembly in the stacking direction is a stipulated
length LT and a bundling pressure of the body to be bundled is a
stipulated pressure P; and the electrode body is formed to match a
stipulated electrode body thickness E by comparing a lamination
direction thickness of an electrode body of a standard
configuration that is predicted from the sheet thickness of the
positive electrode sheet, negative electrode sheet, and separator
sheet to be used to form the electrode body, with the stipulated
electrode body thickness E, and by increasing or decreasing the
amount of the separator sheet used with respect to the standard
configuration.
20. The battery assembly according to claim 19, wherein the
electrode body is a wound electrode body in which the laminated
sheets are wound; the electrode body of the standard configuration
has a configuration in which only the separator sheet is extra
wound at the winding end of the electrode body; and the electrode
body is formed to match the stipulated electrode body thickness E
by increasing or decreasing the number of winding turns of the
separator sheet at the winding end.
21. The battery assembly according to claim 19, wherein a plurality
of unit cells of the same shape are bundled; the plurality of unit
cells are electrically connected to each other by successively
connecting a positive electrode terminal of one of adjacent unit
cells to a negative electrode terminal of the other of the adjacent
unit cells with a connection tool; and a distance between the
positive and negative electrode terminals of any two unit cells
connected by the connection tool is made constant by making uniform
a thickness of bodies accommodated inside the unit cells, and
connection tools of the same predetermined shape are thus used as
the connection tools.
22. The battery assembly according to claim 21, wherein the
electrode body is a wound electrode body in which the laminated
sheets are wound, and has a configuration in which only the
separator sheet is extra wound at the winding end of the wound
electrode body; and a distance between the positive and negative
electrode terminals of any two unit cells connected by the
connection tool is made constant by increasing or decreasing the
number of winding turns of the separator sheet at the winding end
in each unit cell.
23. A vehicle provided with the battery assembly according to claim
19.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for manufacturing
a battery assembly in which a plurality of unit cells (typically,
secondary batteries) are arranged, and more particularly to a
method for manufacturing a battery assembly suitable for
installation on a vehicle.
[0002] The present application claims priority based on Japanese
Patent Application No. 2007-191445 filed on Jul. 23, 2007, and this
patent application is incorporated herein by reference in its
entirety.
BACKGROUND ART
[0003] Battery assemblies in which power storage elements such as
lightweight lithium ion batteries making it possible to obtain a
high energy density, nickel hydrogen batteries, and other secondary
batteries or capacitors, are used as unit cells and a plurality of
unit cells are connected in series have gained importance as power
sources that can produce a high output in applications as power
sources for installation on automobiles or power sources for
personal computers and portable terminals. For example, Patent
Document 1 discloses, as an example of a battery assembly for
installation on a vehicle, a battery assembly configured by
arranging a plurality of unit cells of the same shape composed of
nickel hydrogen secondary batteries and connecting the unit cells
in series. Patent Document 2 is another example of the related art
document that relates to a battery assembly.
[0004] Battery assemblies in which a plurality of lightweight
lithium ion batteries making it possible to obtain a high energy
density is connected as unit cells in series are expected to be
used especially advantageously as high-output power sources for
installation on vehicles.
[0005] Patent Document 1: Japanese Patent Application Laid-Open No.
2001-57196
[0006] Patent Document 2: Japanese Patent Application Laid-Open No.
2005-5167
[0007] In addition to a limited installation space, battery
assemblies that are installed on vehicles such as automobiles are
presumed to be used in a state in which vibrations are generated.
Therefore, for example, as also described in Patent Document 1,
battery assemblies are constructed by arranging and bundling a
large number of unit cells (that is, the unit cells are fixed to
each other). Such bundling is conducted so that the arranged unit
cell group be bundled by an appropriate bundling pressure
(compressive pressure). In order to stabilize the performance
(quality) of battery assemblies, it is preferred that a "spread" in
the bundling pressure among the manufactured battery assemblies
(products) be reduced.
[0008] However, there is generally a certain spread in the outer
shape (for example, a thickness in the arrangement direction) of
individual unit cells used to construct a battery assembly. Where a
large number of unit cells that have such as spread in thickness
are arranged in the stacking direction, the spread in thickness of
the unit cells is accumulated. As a result, the length of the
entire bundling object (body to be bundled) that includes the
arranged unit cells in the stacking direction (arrangement
direction) has a spread equal to or larger than the spread in
thickness of individual unit cells. Where the body to be bundled is
bundled by applying the stipulated bundling pressure, without
regard for the spread in the stacking direction length of the body
to be bundled, a spread occurs in the length of the obtained
battery assembly in the stacking direction, this spread reflecting
the spread (unevenness) of the stacking direction length of the
body to be bundled. For example, the stacking direction length of
the battery assembly in which the body to be bundled that has a
relatively large stacking direction length is bundled by the
stipulated bundling pressure is larger than the stacking direction
length of the battery assembly in which the body to be bundled that
has a relatively small stacking direction length is bundled under
the same bundling pressure.
[0009] When the battery assemblies are installed on vehicles, this
spread in the stacking direction length (outer size) of the battery
assemblies causes inconveniences, for example, the battery assembly
cannot be accommodated in the installation space that has been
prepared in advance or an extra gap remains when the battery
assembly is accommodated in the gap. Therefore, in the manufacture
of battery assemblies, it is desirable not only to reduce the
spread in bundling pressure of the battery assemblies, but also to
reduce the spread in stacking direction length.
DISCLOSURE OF THE INVENTION
[0010] Accordingly, it is an object of the present invention to
provide a method for manufacturing with good efficiency a battery
assembly in which a plurality of unit cells are bundled by the
preset (stipulated) bundling pressure and which has a preset
accurate size (in particular, a length dimension of the battery
assembly in the stacking direction of the unit cells constituting
the battery assembly). Another object of the present invention is
to provide a battery assembly obtained by this manufacturing method
and a vehicle provided with the battery assembly.
[0011] The present invention provides a method for manufacturing a
battery assembly in which a predetermined number of unit cells
(typically, secondary batteries) are arranged in a stacking
direction. This method includes a step of preparing a plurality of
unit cells (for example, the unit cells may be manufactured from
components or semi-products or may be prepared by purchasing or the
like). Further, the method includes a step of measuring a stacking
direction length L1 of a stacked body including the predetermined
number of the unit cells arranged in the stacking direction. The
method also includes a step of bundling a body to be bundled that
includes the stacked body. The body to be bundled includes length
adjusting means for converging a spread in stacking direction
length L1. The bundling step is implemented by setting the length
adjusting means according to the length L1, so that a length of the
battery assembly in the stacking direction is a stipulated length
LT and a bundling pressure of the body to be bundled is a
stipulated pressure (stipulated bundling pressure) P.
[0012] The "unit cells" as referred to in the present description
is a term indicating individual power storage elements constituting
a battery assembly and includes batteries and capacitors of various
compositions, unless specifically stated otherwise. Further, the
term "secondary battery" refers generally to batteries that can be
repeatedly charged and discharged and covers the so-called storage
batteries such as a lithium ion battery and a nickel hydrogen
battery. A power storage element constituting a lithium ion battery
is a typical example of a configuration included in the definition
of "unit cell" referred to herein, and a lithium ion battery module
constituted by a plurality of such unit cells is a typical example
of "battery assembly" disclosed herein. The technique disclosed
herein can be applied especially advantageously to a battery
assembly in which a predetermined number of unit cells (for
example, lithium ion batteries) having a flat outer shape are
arranged in a direction in which the flat planes are placed one on
another (stacking direction) and the electrode terminals of these
unit cells are connected in series or parallel.
[0013] In the battery assembly manufacturing method of the
above-described configuration, a predetermined number of unit cells
(typically, a predetermined number of unit cells of the same shape)
that are used to constitute the battery assembly are stacked, a
stacking direction length L1 of the stacked body is measured, and
the length adjusting means is set so as to converge a spread in
length L1 and realize the stipulated length LT and stipulated
pressure P on the basis of the length L1. The stacking direction
length L1 is measured as a length of all the constituent elements
of the stacked body (includes at least the predetermined number of
unit cells, but also may include elements other that the unit cells
that can constitute the body to be bundled, for example cooling
plates sandwiched between the unit cells and an end plate disposed
at one end of the stacked body, as described in Examples 1 to 9
below) and therefore can be measured with higher accuracy than the
stacking direction length of each constituent element. Therefore,
with the above-described method, a battery assembly can be
manufactured in which the bundling pressure of the entire body to
be bundled and the stacking direction length of the battery
assembly are matched with good accuracy with the stipulated values
(stipulated length LT and stipulated pressure P). Further, because
it is not necessary to measure successively the stacking direction
length (that is, thickness) of each unit cell used to construct the
battery assembly, a battery assembly with a small spread in
bundling pressure and small spread in stacking direction length can
be efficiently manufactured. Therefore, with the manufacturing
method in accordance with the present invention, it is possible to
provide a battery assembly suitable for installation on a vehicle
or for other applications, this battery assembly being provided
with good performance (quality) and external size (stacking
direction length).
[0014] A spacer member that is arranged together with the stacked
body in the stacking direction and constitutes the body to be
bundled can be presented as a preferred example of the length
adjusting means. The bundling step is implemented by setting the
spacer member according to the length L1. Typically, a spacer
member of an adequate size (stacking direction length, that is,
thickness) is selected with consideration for the length L1, and
the body to be bundled is formed by using the selected spacer
member (that is, the length adjusting means is set). More
specifically, a spacer member may be used of a thickness so as to
make it possible to form a body to be bundled with a stacking
direction length that constitutes the battery assembly of the
stipulated length LT when the spread in length L1 is converged and
the body to be bundled is bundled by the stipulated pressure
(bundling pressure) P where the spacer member is arranged together
with other constituent elements of the body to be bundled. It is
preferred that a plurality of spacer members that differ at least
in thickness be prepared in advance so that the spacer members of
adequate thickness be disposed with good efficiency, or that a
plurality of spacer members be used in combination to adjust the
total thickness of these spacer members to the appropriate
thickness. For example, a mode can be advantageously used in which
the spacer members prepared in a sheet-like form and having a
predetermined thickness are used in the number corresponding to the
aforementioned length L1 (in addition to the constituent elements
of the body to be bundled).
[0015] An end plate disposed in at least one stacking end of the
body to be bundled and configured so that a length thereof in the
stacking direction can be changed can be presented as another
preferred example of the length adjusting means. The bundling step
is typically implemented by adjusting the stacking direction length
(that is, thickness) of the end plate member to the adequate
thickness with consideration for the length L1, forming the body to
be bundled of a configuration that includes the end plate with the
adjusted thickness (that is, setting the length adjusting means),
and bundling the body to be bundled so as to obtain the stipulated
pressure P and stipulated length LT. The thickness of the end plate
may be adjusted (for example, adjusted by a screwing degree in the
setscrew mechanism such as described in Example 2 below) to a
thickness such that makes it possible to converge the spread in
length L1 and to form a body to be bundled of a stacking direction
length that constitutes the battery assembly of the stipulated
length LT when the body to be bundled is bundled by the stipulated
pressure (bundling pressure) P.
[0016] The length adjusting means may be an elastic member that is
arranged together with the stacked body in the stacking direction
and constitutes the body to be bundled. In this case, the bundling
step is implemented by selecting an elastic member demonstrating an
adequate elastic force (repulsion force) with consideration for the
length L1, forming the body to be bundled by using the selected
elastic member (that is, setting the length adjusting means), and
bundling the body to be bundled so as to obtain the stipulated
pressure P and stipulated length LT. More specifically, it is
possible to use an elastic member having characteristics such that
the spread in length L1 is converged and the repulsion force acting
when bundling is conducted to configure the battery assembly of the
stipulated length LT (when the elastic member is compressed)
becomes the stipulated pressure (bundling pressure) P where the
elastic member is arranged together with other constituent elements
of the body to be bundled.
[0017] The present invention also provides a method for
manufacturing a battery assembly in which a predetermined number of
unit cells are arranged in a stacking direction, the method
including the steps of: preparing (manufacturing or purchasing) a
plurality of unit cells and measuring a stacking direction length
L1 of a stacked body including the predetermined number of the unit
cells arranged in the stacking direction. This manufacturing method
includes a step of bundling a body to be bundled that includes the
stacked body, so that a bundling pressure of the body to be bundled
is a stipulated pressure P. Further, the method includes a step of
disposing an externally attached spacer at the outside in the
stacking direction of the bundled body that has been bundled by the
stipulated pressure P, the externally attached spacer serving to
converge a spread in stacking direction length L1 and match the
length of the battery assembly in the stacking direction with a
stipulated length LT.
[0018] With the manufacturing method of such a configuration, an
externally attached spacer is used that has an adequate size
(stacking direction length, that is, thickness) determined with
consideration for the stacking direction length L1 of the stacked
body. As described hereinabove, this length L1 can be measured with
an accuracy higher than that of the stacking direction length of
individual constituent elements. Therefore, it is possible to
manufacture a battery assembly in which the bundling pressure and
the stacking direction length of the battery assembly match the
stipulated values (stipulated length LT and stipulated pressure P)
with higher accuracy. Further, the bundling pressure is not applied
to the externally attached spacer and the externally attached
spacer is not deformed (compression deformation) by the bundling
pressure. Therefore, the stacking direction length of the battery
assembly can be adjusted with better accuracy. Further, because the
operation of measuring successively the thickness of individual
unit cells that are used is unnecessary, battery assemblies with
well-matched bundling pressure and stacking direction length can be
manufactured with good efficiency.
[0019] With consideration for the length L1, the externally
attached spacer is used that has a size (stacking direction length,
that is, thickness) adequate to match the stacking direction length
of the battery assembly with the stipulated length LT. More
specifically, the externally attached spacer may be used that is
configured so that the spread in stacking direction length B of the
bundled unit obtained by bundling the body to be bundled by the
stipulated bundling pressure P (can be the length reflecting the
spread in length L1) can be converged and a stacking direction
length necessary to match the stacking direction length of the
battery assembly with the stipulated length LT can be added to the
body to be bundled.
[0020] The present invention also provides a method for
manufacturing a battery assembly in which a predetermined number of
unit cells are arranged in a stacking direction, comprising the
steps of: preparing the predetermined number of unit cells and
measuring a stacking direction thickness for each of these unit
cells. The method includes a step of forming a body to be bundled
that includes the predetermined number of unit cells arranged in
the stacking direction. Further, the method includes a step of
bundling the body to be bundled so that a length of the battery
assembly in the stacking direction is a stipulated length LT and a
bundling pressure of the body to be bundled is a stipulated
pressure P. In this case, the step of forming the body to be
bundled includes a length adjustment processing of converging a
spread of a total value CT of stacking direction thicknesses of the
predetermined number of unit cells. The length adjustment
processing is a processing of arranging one or a plurality
(typically, a plurality) of spacing adjusting members that have a
total thickness FT corresponding to the total value CT together
with the predetermined number of unit cells in the stacking
direction. In this processing, the spacing adjusting members are
disposed (distributed) between the unit cells so as to obtain a
constant stacking pitch of the unit cells.
[0021] With the manufacturing method of the above-described
configuration, the spacing adjusting members are used that have a
total thickness FT which makes it possible to converge the total
value CT and realize the stipulated length LT and stipulated
pressure P according to the total value CT. As a result, it is
possible to provide battery assemblies with well-matched bundling
pressure and stacking direction length. When the manufacturing
method of the battery assembly further includes a step of
connecting the terminals of the bundled unit cells in series or
parallel, if the stacking pitch of the unit cells is uneven due to
a spread in unit cell thickness, it can result in inconveniences.
For example, the terminal connection tools that have been
fabricated to predetermined shape and size cannot be used between
some of the unit cells. In this case, with the above-described
manufacturing method, because the stacking pitch of the unit cells
is adjusted to a constant pitch by the spacing adjusting members,
the stacking pitch of the unit cells contained in the battery
assembly can be made uniform. Therefore, the terminals of unit
cells can be efficiently connected by the terminal connection tools
that have been fabricated to predetermined shape and size.
[0022] The present invention also provides a method for
manufacturing a battery assembly in which a predetermined number of
unit cells are arranged in a stacking direction, including the
steps of: preparing a plurality of unit cells and measuring a
stacking direction thickness for each of these unit cells. The
method includes a step of classifying the plurality of unit cells
into a plurality of thickness ranks with mutually different
thickness ranges based on the stacking direction thickness.
Further, the method includes a step of selecting the predetermined
number of unit cells from one, or two or more thickness ranks from
among the plurality of thickness ranks so that the sum total of
representative values of the thickness ranks to which the unit
cells belong is a stipulated length RT. The method also includes a
step of forming a body to be bundled that includes the selected
unit cells arranged in the stacking direction. In addition, the
method includes a step of bundling the body to be bundled so that a
length of the battery assembly in the stacking direction is a
stipulated length LT and a bundling pressure of the body to be
bundled is a stipulated pressure P. In this method, the stipulated
length RT in the unit cell selection step is set to a length
corresponding to the stipulated length LT and stipulated pressure
P.
[0023] With this manufacturing method, the predetermined number of
unit cells are selected such that the spread in thickness of
individual unit cells is absorbed and the total thickness of these
unit cells converges to the stipulated thickness RT. Therefore, by
adequately (that is, so as to obtain the stipulated thickness RT)
combining and arranging a plurality of unit cells having a spread
in thickness, it is possible to manufacture a battery assembly with
the stipulated stacking direction length LT and bundling pressure P
with higher accuracy even when the degree of thickness spread
(shape accuracy) of the unit cells is at the conventional level.
This is useful from the standpoint of production cost of unit
cells. Further, in this manufacturing method, the stacking
direction length LT at the bundling pressure P is adjusted by
combining the unit cells selected from thickness ranks and no novel
components are necessary to implement the method. The resultant
advantage is that it is not necessary to increase the number of
parts constituting the battery assembly.
[0024] In any of the above-described methods for manufacturing a
battery assembly, unit cells that are prepared by a step of
constructing a plurality of unit cells of the same shape, each unit
cell including an electrode body in which a positive electrode
sheet and a negative electrode sheet are laminated together with a
separator sheet, a container that accommodates the electrode body
and an electrolyte, and a positive electrode terminal and a
negative electrode terminal that are electrically connected to the
positive electrode and the negative electrode and are disposed
outside the container, can be advantageously used as the plurality
of unit cells. The step of constructing the plurality of unit cells
can include a processing in which one, or two or more of positive
electrode sheets, negative electrode sheets, and separator sheets
to be used to form the electrode bodies are selected from a
plurality of positive electrode sheets, a plurality of negative
electrode sheets, and a plurality of separator sheets that have
been classified into a plurality of thickness ranks based on the
sheet thickness and the electrode bodies are formed by using the
selected positive electrode sheets, negative electrode sheets, and
separator sheets. In this case, the sheets to be used to form the
electrode bodies are selected from one, or two or more thickness
ranks from among the plurality of thickness ranks, so that the sum
total of representative values of the thickness ranks to which
these sheets belong is a stipulated thickness ST.
[0025] In the unit cells that have thus been prepared (by
manufacturing the unit cells by the above-described process or
purchasing the unit cells manufactured by the above-described
process), the sheets are selected such that the spread in thickness
of individual sheets (electrode sheets of positive and negative
electrodes and separator sheets that are used to form the electrode
bodies) is absorbed and the total thickness of these sheets is
converged to the stipulated thickness ST. Therefore, by adequately
combining a plurality of sheets having a spread in thickness, it is
possible to reduce a spread in thickness in the sheet lamination
direction in an electrode body of a laminated type in which the
sheets are laminated and an electrode body of a wound type (wound
electrode body) in which the laminated sheets are wound, even when
the degree of thickness spread in sheets is at the conventional
level. By so reducing the spread in thickness of the electrode
bodies, it is possible to reduce the spread in thickness of unit
cells in which the electrode bodies are accommodated in containers.
Therefore, by using such unit cells it is possible to manufacture a
battery assembly having the stipulated stacking direction length LT
and bundling pressure P with better accuracy.
[0026] The effect of the present invention, which is in the
possibility of manufacturing a battery assembly having the
stipulated stacking direction length LT and bundling pressure P
with better accuracy by adequately selecting the sheets
constituting the electrode bodies and reducing the spread in
thickness of unit cells, can be advantageously applied to a method
for manufacturing a battery assembly of a mode including a step of
measuring the stacking direction thickness for each of these unit
cells and/or a step of measuring the stacking direction length L1
of the stacked body, and also to a method for manufacturing a
battery assembly of a mode that does not require these steps.
Therefore another aspect of the present invention relates to a
method for manufacturing a battery assembly in which a
predetermined number of unit cells are arranged in a stacking
direction, including the steps of: constructing a plurality of unit
cells of the same shape, each unit cell including an electrode body
in which a positive electrode sheet and a negative electrode sheet
are laminated together with a separator sheet, a container that
accommodates the electrode body and an electrolyte, and a positive
electrode terminal and a negative electrode terminal that are
electrically connected to the positive electrode and the negative
electrode and are disposed outside the container; forming a body to
be bundled that includes the predetermined number of unit cells
arranged in the stacking direction; and bundling the body to be
bundled so that a length of the battery assembly in the stacking
direction is the stipulated length LT and a bundling pressure of
the body to be bundled is a stipulated pressure P. In this case,
the step of constructing the plurality of unit cells includes a
processing in which one, or two or more of positive electrode
sheets, negative electrode sheets, and separator sheets to be used
to form the electrode bodies are selected from a plurality of
positive electrode sheets, a plurality of negative electrode
sheets, and a plurality of separator sheets that have been
classified into a plurality of thickness ranks based on the sheet
thickness and the electrode bodies are formed by using the selected
positive electrode sheets, negative electrode sheets, and separator
sheets. Further, the sheets to be used to form the electrode bodies
are selected from one, or two or more thickness ranks from among
the plurality of thickness ranks, so that the sum total of
representative values of the thickness ranks to which these sheets
belong is a stipulated thickness ST.
[0027] Another preferred example of the unit cells that can be used
in any of the methods for manufacturing a battery assembly
disclosed herein relates to unit cells prepared by a step of
constructing a plurality of unit cells of the same shape, each unit
cell including an electrode body in which a positive electrode
sheet and a negative electrode sheet are laminated together with a
separator sheet, a container that accommodates the electrode body
and an electrolyte, and a positive electrode terminal and a
negative electrode terminal that are electrically connected to the
positive electrode and the negative electrode and are disposed
outside the container. The step of constructing the plurality of
unit cells includes a processing in which a lamination direction
thickness of an electrode body of a standard configuration that is
predicted from the sheet thickness of the positive electrode sheet,
negative electrode sheet, and separator sheet to be used to form
the electrode body is compared with a stipulated electrode body
thickness (target value of the electrode body thickness measured in
the stacking direction of the unit cells including the electrode
body) E, and the electrode body is formed to match the stipulated
electrode body thickness E by increasing or decreasing the amount
of the separator sheet used with respect to the standard
configuration.
[0028] By so increasing or decreasing the amount of the separator
sheet to match the stipulated electrode body thickness E, it is
possible to form electrode bodies of more uniform thickness (small
spread) and therefore the spread in thickness of unit cells in
which the electrode body is accommodated in the container can be
reduced. Therefore, by using such unit cells, it is possible to
manufacture the battery assembly having the stipulated stacking
direction length LT and bundling pressure P with better accuracy.
The increase or decrease in the amount of the separator sheet used
can be performed for example by increasing or decreasing the number
of the separator sheet so as to match the stipulated electrode body
thickness E. Further, in an electrode body of a wound type (wound
electrode body), this increase or decrease can be performed by
winding the separator sheet in excess on the outer circumference
(winding end portion) of the electrode body so as to match the
stipulated electrode body thickness E. Alternatively, the separator
sheet may be wound in excess on the inner circumference (winding
start portion) of the electrode body.
[0029] The effect of the present invention, which is in the
possibility of reducing the spread in thickness of unit cells and
manufacturing a battery assembly having the stipulated stacking
direction length LT and bundling pressure P with better accuracy by
adequately increasing or decreasing the amount of separator sheets
used can be advantageously applied to a method for manufacturing a
battery assembly of a mode including a step of measuring the
stacking direction thickness for each of these unit cells and/or a
step of measuring the stacking direction length L1 of the stacked
body, and also to a method for manufacturing a battery assembly of
a mode that does not require these steps. Therefore another aspect
of the present invention relates to a method for manufacturing a
battery assembly in which a predetermined number of unit cells are
arranged in a stacking direction, including the steps of:
constructing a plurality of unit cells of the same shape, each unit
cell including an electrode body in which a positive electrode
sheet and a negative electrode sheet are laminated together with a
separator sheet, a container that accommodates the electrode body
and an electrolyte, and a positive electrode terminal and a
negative electrode terminal that are electrically connected to the
positive electrode and the negative electrode and are disposed
outside the container; forming a body to be bundled that includes
the predetermined number of unit cells arranged in the stacking
direction; and bundling the body to be bundled so that a length of
the battery assembly in the stacking direction is the stipulated
length LT and a bundling pressure of the body to be bundled is a
stipulated pressure P. In this case, the step of constructing the
plurality of unit cells includes a processing in which a lamination
direction thickness of an electrode body of a standard
configuration that is predicted from the sheet thickness of the
positive electrode sheet, negative electrode sheet, and separator
sheet to be used to form the electrode body is compared with a
stipulated electrode body thickness E, and the electrode body is
formed to match the stipulated electrode body thickness E by
increasing or decreasing the amount of the separator sheet used
with respect to the standard configuration.
[0030] Another preferred example of the unit cells that can be used
in any of the methods for manufacturing a battery assembly
disclosed herein relates to unit cells prepared by a step of
constructing a plurality of unit cells of the same shape, each unit
cell including an electrode body in which a positive electrode
sheet and a negative electrode sheet are laminated together with a
separator sheet, a container that accommodates the electrode body
and an electrolyte, and a positive electrode terminal and a
negative electrode terminal that are electrically connected to the
positive electrode and the negative electrode and are disposed
outside the container. The step of constructing the plurality of
unit cells includes a processing in which a lamination direction
thickness of the electrode body is measured and one or a plurality
of gap filling materials are disposed in the lamination direction
of the electrode body between the electrode body and an inner wall
of the container according to the measured value of the lamination
direction thickness, thereby adjusting the combined lamination
direction thickness of the electrode body and the gap filling
materials to a stipulated value A.
[0031] By so adjusting the combined thickness of the body (in this
case, the electrode body and the gap filling material) that will be
accommodated in the container to the stipulated value A, it is
possible to form electrode bodies with more uniform thickness
(smaller spread in thickness) and reduce a spread in thickness of
the unit cells that will be thereafter obtained by accommodating
the electrode bodies in the containers. Therefore, by using such
unit cells, it is possible to manufacture a battery assembly having
the stipulated stacking direction length LT and bundling pressure P
with better accuracy. For example, fillers formed in sheets can be
advantageously used as the gap filling material, and the total
thickness of the electrode body and gap filling material can be
easily adjusted to match the stipulated value A by increasing or
decreasing the number of gap filling material sheets that are
used.
[0032] As described hereinabove, the battery assembly manufactured
by any of the above-disclosed methods excels in stable quality and
therefore can be advantageously used as a battery assembly for
installation on a vehicle (for example, a battery for a motor
(electric motor) of a vehicle such as an automobile). Therefore,
the present invention provides a vehicle equipped with any of the
battery assemblies disclosed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a perspective view illustrating the configuration
of a battery assembly of Example 1.
[0034] FIG. 2 is a side view illustrating the configuration of a
battery assembly of Example 1.
[0035] FIG. 3 is a plan view illustrating schematically an example
of a wound electrode body.
[0036] FIG. 4 is a cross-sectional view illustrating schematically
a configuration of unit cells of the battery assembly of Example
1.
[0037] FIG. 5 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 1.
[0038] FIG. 6 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 1.
[0039] FIG. 7 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 2.
[0040] FIG. 8 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 2.
[0041] FIG. 9 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 3.
[0042] FIG. 10 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 4.
[0043] FIG. 11 is a side view illustrating schematically a method
for manufacturing the battery assembly of Example 5.
[0044] FIG. 12 is an explanatory drawing illustrating schematically
a method for manufacturing the battery assembly of Example 6.
[0045] FIG. 13 is an explanatory drawing illustrating schematically
a method for manufacturing a unit cell of the battery assembly of
Example 7.
[0046] FIG. 14 is an explanatory drawing illustrating schematically
a method for manufacturing a unit cell of the battery assembly of
Example 7.
[0047] FIG. 15 is an explanatory drawing illustrating schematically
a method for manufacturing a unit cell of the battery assembly of
Example 8.
[0048] FIG. 16 is an explanatory drawing illustrating schematically
a method for manufacturing a unit cell of the battery assembly of
Example 9.
[0049] FIG. 17 is an explanatory drawing illustrating schematically
a method for manufacturing the battery assembly of Example 9.
[0050] FIG. 18 is a side view illustrating schematically a vehicle
(automobile) equipped with a battery assembly.
BEST MODE FOR CARRYING OUT THE INVENTION
[0051] The preferred embodiments of the invention will be described
below. A matter other than the subject specifically referred to in
the present description, but necessary to carry out the invention
(for example, methods for manufacturing a positive electrode, a
negative electrode, and a separator, configurations thereof, a
method for bundling the unit cells, and a method for installing a
battery assembly on a vehicle) may be understood as a design matter
for a person skilled in the art on the basis of a related art in
the pertinent field. The present invention can be implemented on
the basis of the contents disclosed in the present description and
general technical knowledge in the pertinent field.
[0052] In the battery assembly manufactured by applying the
technique disclosed herein, the configuration of each unit cell is
not particularly limited, provided that the battery assembly has
the unit cells (typically unit cells having a flat outer shape)
that are arranged and bundled in the arrangement direction
(stacking direction). Examples of unit cells that are preferred as
the application objects of the present invention include secondary
batteries such as nickel-hydrogen batteries and electric double
layer capacitors. Among them, the present invention can be
advantageously employed as a method for manufacturing a battery
assembly using a lithium ion battery as a unit cell. Because the
lithium ion battery is a secondary battery that can realize a high
output at a high energy density, such a battery can be used to
construct a high-performance battery assembly, in particular a
battery assembly (battery module) for installation on a vehicle.
Further, the present invention is advantageous as a method for
manufacturing a battery assembly of a configuration in which a
plurality of such arranged unit cells are connected in series or
parallel (typically, in series).
[0053] The present invention will be described below in greater
detail by the example in which a flat-shaped lithium ion battery is
used as a unit cell and a battery assembly is manufactured in which
a plurality of such unit cells are connected in series. In the
drawings, members and components demonstrating like actions will be
assigned with like reference numerals and the redundant explanation
thereof is omitted or simplified.
Example 1
[0054] Similarly to a unit cell provided in the conventional
battery assembly, a unit cell used as a constituent element of the
battery assembly manufactured in each of the below-described
embodiments typically includes an electrode body composed of
predetermined constituent material of the battery (active materials
of positive and negative electrodes, collectors of positive and
negative electrodes, separator, etc.) and a container that
accommodates the electrode body and an appropriate electrolyte.
[0055] As an example, as shown in FIG. 1 and FIG. 2, a battery
assembly 10 of the present example includes a predetermined number
(typically 10 or more, preferably about 10 to 30, for example, 20)
unit cells 12 of the same shape. The unit cell 12 has a container
14 of a shape (in the present embodiment, a flat box-like shape)
that can accommodate the below-described flat-shaped wound
electrode body. The "same shape" of the unit cells 12 means that
the cells have been manufactured to the same target dimensions and
does not necessarily mean that the dimensions of each portions are
absolutely identical. The side of portions of the unit cells 12
(for example, the external shape such as thickness in the stacking
direction) can have a spread due to a dimensional error in the
manufacture of the container 14 used.
[0056] The container 14 is provided with a positive electrode
terminal 15 for electric connection to the positive electrode of
the wound electrode body and a negative electrode terminal 16 for
electric connection to the negative electrode of the electrode
body. As shown in the figure, the positive electrode terminal 15 of
one of the adjacent unit cells 12 is electrically connected to the
negative electrode terminal 16 of the other of the adjacent unit
cells with a connection tool 17. The battery cell 10 of a desired
voltage is thus constructed by connecting the unit cells 12 in
series.
[0057] Similarly to the conventional unit cell container, a safety
valve for releasing the gas generated inside the container can be
provided in the container 14. The configuration of such a container
14 does not by itself characterizes the present invention and
therefore the detailed explanation thereof is omitted.
[0058] The material of the container 14 is not particularly
limited, provided that it is identical to the material used in the
conventional until cells. For example a metallic (for example,
aluminum or steel) container, a synthetic resin (for example, a
polyolefin resin such as polypropylene or a high-melting resin such
as polyethylene terephthalate, polytetrafluoroethylene, and a
polyamide resin) container can be used. The container 14 in the
present example is made, for example, from aluminum.
[0059] As shown in FIG. 1 and FIG. 2, a plurality of unit cells 12
of the same shape are arranged in the direction facing a wide plane
14A of the container 14 (that is, a plane facing a flat plane of
the below-described wound electrode body 30 accommodated inside the
container 14), while inverting every other unit cell so that the
positive electrode terminals 15 and negative electrode terminals 16
of the unit cells are disposed alternately. Cooling plates 11 of a
predetermined shape are disposed in a state of intimate contact
with the wide plane 14A of the container 14 between the arranged
unit cells 12 and at both outer sides in the unit cell arrangement
direction (stacking direction). The cooling plates 11 function as
heat dissipating members serving to dissipate efficiently the heat
generated inside the unit cells in use. The cooling plates have a
frame shape (for example, a concave-convex shape, as viewed from
the side surface, such as a comb-like shape shown in the figure)
that enables the introduction of a cooling fluid (typically, the
air) between the unit cells 12. Cooling plates 11 made from a metal
with good thermal conductivity or a lightweight and hard synthetic
resin such as polypropylene can be advantageously used.
[0060] A pair of end plates 18, 19 are disposed further outside of
the cooling plates 11 disposed at both outer sides of the arranged
until cells 12 and cooling plates 11 (referred together hereinbelow
as "unit cell group"). A spacer member 40 serving as length
adjusting means is inserted between the cooling plate 11 and end
plate 18 disposed at one (right end in FIG. 2) outer side of the
unit cell group. The spacer member 40 is constituted by one or a
plurality of stacked (three are shown in FIG. 2) sheet-like spacers
(spacer sheets) 42. The constituent material of the spacer members
40 (spacer sheets 42) is not particularly limited and various
materials (metallic materials, resin materials, ceramic materials,
and the like) can be used, provided that they can demonstrate the
below-described length adjusting function. From the standpoint of
endurance against impacts, the use of metallic materials or resin
materials is preferred. For example, the spacer member 40 made from
a lightweight polyolefin resin can be advantageously used. In the
present example, polypropylene sheets of the same thickness
(typically a thickness of 0.03 mm to 3 mm, preferably 0.1 mm to 1
mm) are used as the spacer sheets 42.
[0061] The entire body (referred to hereinbelow as "body to be
bundled") 20 composed of the unit cell groups, spacer members 40,
and end plates 18, 19 arranged in the stacking direction of the
unit cells 12 is bundled by a stipulated bundling pressure P in the
stacking direction of the body to be bundled, using a bundling band
21 for tightening that is wrapped around so as to bridge both end
plates 18, 19. More specifically, as shown in FIG. 2, the end
portions of the bundling band 21 are tightened and fixed to the end
plate 18 with screws 22, whereby the body 20 to be bundled is
bundled so that a stipulated bundling pressure P (for example such
that a surface pressure received by the wall surface of the
container 14 is about 2.times.10.sup.6 to 5.times.10.sup.6 Pa) is
applied in the arrangement direction of the body to be bundled. The
length (in the example shown in FIGS. 1 and 2, the length between
the outer ends of the end plates 18 and 19) in the stacking
direction of the battery assembly 10 bundled by such a stipulated
bundling pressure P is a stipulated length LT.
[0062] With the manufacturing method of the present example, as
will be described hereinbelow, the battery assembly 10 having the
above-described configuration can be manufactured with good
efficiency so as to realize the stipulated bundling pressure P and
stipulated length LT with good stability. This manufacturing method
will be explained below with reference to schematic diagrams shown
in FIGS. 3 to 6.
[0063] First, a step of preparing the predetermined number of unit
cells 20 that will be used to construct the battery assembly 10
will be described. Similarly to a wound electrode body of the usual
lithium ion battery, the until cell 20 has a flat-shaped wound
electrode body 30 fabricated by laminating a sheet-like positive
electrode 32 (can be also referred to hereinbelow as "positive
electrode sheet 32"), a sheet-like negative electrode 34 (can be
also referred to hereinbelow as "negative electrode sheet 34"), and
a total of two sheet-like separators 36 (referred to hereinbelow as
"separator sheets 36"), winding, while somewhat shifting the
positive electrode sheet 32 and negative electrode sheet 34, and
then flattening the obtained wound body from the side surface
direction thereof.
[0064] As shown in FIG. 3, as a result of winding with the
above-described shift in the transverse direction with respect to
the winding direction of this wound electrode body 30, end parts of
the positive electrode sheet 32 and negative electrode sheet 34
protrude to the outside from a wound core portion 31 (that is, a
portion obtained by tightly winding a positive electrode active
material layer formation portion of the positive electrode sheet
32, a negative electrode active material layer formation portion of
the negative electrode sheet 34, and the separator sheet 36). A
positive electrode lead terminal 32B and a negative electrode lead
terminal 34B are attached to a positive electrode protruding
portion (that is, a portion that does not form the positive
electrode active material layer) 32A and a negative electrode
protruding portion (that is, a portion that does not form the
negative electrode active material layer) 34A, and these lead
terminals 32B, 34B are electrically connected to the aforementioned
positive electrode terminal 15 and negative electrode terminal 16,
respectively.
[0065] The materials constituting the wound electrode body 30 and
the members themselves are not particularly restricted and may be
identical to those of the electrode body of the conventional
lithium ion battery. For example, the positive electrode sheet 32
can be formed by providing a positive electrode active material
layer for a lithium ion battery on an elongated positive electrode
collector. An aluminum foil (present embodiment) or other metal
foil suitable for the positive electrode can be advantageously used
for the positive electrode collector. One, or two or more
substances that have been conventionally used in lithium ion
batteries can be used without any particular limitation for the
positive electrode active material. The preferred examples include
lithium transition metal oxides such as LiMn.sub.2O.sub.4,
LiCoO.sub.2, and LiNiO.sub.2. For example, the advantageous
positive electrode sheet 32 can be obtained by using an aluminum
foil with a length of about 2 m to 4 m (for example 23 m), a width
of about 8 cm to 12 cm (for example, 10 cm), and a thickness of
about 5 .mu.m to 20 .mu.m (for example, 15 .mu.m) as the collector,
and forming a positive electrode active material layer (for
example, lithium nickel oxide 88 wt. %, acetylene black 10 wt. %,
polytetrafluoroethylene 1 wt. %, and carboxymethyl cellulose 1 wt.
%) for a lithium ion battery that is based on a lithium nickel
oxide by the usual method on the predetermined region of the
collector surface.
[0066] The negative electrode sheet 34 can be formed by providing a
negative electrode active material layer for a lithium ion battery
on an elongated negative electrode collector. A copper foil
(present embodiment) or other metal foil suitable for the negative
electrode can be advantageously used for the negative electrode
collector. One, or two or more substances that have been
conventionally used in lithium ion batteries can be used without
any particular limitation for the negative electrode active
material. The preferred examples include carbon-containing
materials such as graphite carbon and amorphous carbon, lithium
transition metal oxides, and transition metal nitrides. For
example, the advantageous negative electrode sheet 34 can be
obtained by using a copper foil with a length of about 2 m to 4 m
(for example 2.9 m), a width of about 8 cm to 12 cm (for example,
10 cm), and a thickness of about 5 .mu.m to 20 .mu.m (for example,
10 .mu.m) as the collector, and forming a negative electrode active
material layer (for example, graphite 98 wt. %, styrene-butadiene
rubber 1 wt. %, and carboxymethyl cellulose 1 wt. %) for a lithium
ion battery that is based on graphite by the usual method on the
predetermined region of the collector surface.
[0067] The preferred separator sheet 36 used between the positive
and negative electrode sheets 32, 34 is constituted for example by
a porous polyolefin resin. For example, a porous separator sheet
from a synthetic resin (for example, a polyolefin such as
polyethylene) with a length of about 2 m to 4 m (for example 3.1
m), a width of about 8 cm to 12 cm (for example, 11 cm), and a
thickness of about 5 .mu.m to 30 .mu.m (for example, 25 .mu.m) can
be advantageously used. When a solid electrolyte or a gelled
electrolyte is used as the electrode, the separator is sometimes
unnecessary (that is, in this case, the electrolyte itself can
function as the separator).
[0068] The flat-shaped wound electrode body 30 thus obtained is
accommodated inside the container 14 so that the winding axis is
side toppled as shown in FIG. 4, a nonaqueous electrolyte
(electrolytic solution) such as a mixed solvent (for example, a
mass ratio of 1:1) of diethyl carbonate and ethylene carbonate
including an appropriate amount (for example, a concentration of 1
M) of an appropriate support salt (for example, a lithium salt such
as LiPF.sub.6) is poured in, and the container is sealed to produce
the unit cell 12.
[0069] Then, as shown schematically in FIG. 5, the predetermined
number of unit cells 12 to be used in the manufacture of the
battery assembly 10 are arranged in the stacking direction together
with the predetermined number (the number sufficient to dispose the
cooling plates between the unit cells 12 and at both outer sides of
the arrangement) of cooling plates 11 used in the manufacture of
the battery assembly 10. Then, end plates 18, 19 are disposed at
both ends of the arrangement. The stacking direction length L1 of
the unit cells--cooling plates--end plates stacked body 24 that is
configured as described hereinabove is measured and the measured
value obtained (length L1 of the stacked body 24 in the stacking
direction) is compared with the target value L0 of the stacking
direction length of the body 20 to be bundled that has been set in
advance. The target value L0 is set so as to configure a battery
assembly of a stipulated stacking direction length LT by bundling
the body 20 to be bundled that has the stacking direction length L0
with the stipulated bundling pressure P, in order words, so as to
realize the stipulated bundling pressure P by wrapping around the
bundling band 21 of a shape and size that enable the configuration
of the battery assembly with the stipulated stacking direction
length LT to the above-described body 20 to be bundled (that is,
the body having the stacking direction length L0). The target value
L0 can be set on the basis of past results obtained in the process
of manufacturing battery assemblies or can be readily found by
preliminary tests.
[0070] As described hereinabove, the thickness of the predetermined
number of unit cells 12 typically has a spread caused for example
by a dimensional error in the manufacture of the containers 14 that
will be used. Therefore, the stacking direction length L1 of the
stacked body 24 that includes the predetermined number of unit
cells 12 arranged in the stacking direction has a spread reflecting
the spread in thickness of these unit cells 12. A spacer member
(length adjusting means) 40 is selected that has a thickness
suitable to compensate for the difference between the stacking
direction length L1 (actually measured value) of the stacked body
24 and the target value L0 according to the stipulated stacking
direction length L1 measured with respect to the stacked body 24 to
be used in the manufacture of the battery assembly 10, so as to
converge the spread in stacking direction length L1. Thus, FIG. 6
shows an example in which three spacer sheets are used as the
spacer member 40, but the thickness of the spacer member 40 (total
thickness of the spacer sheets) can be adjusted and the spread in
stacking direction length L1 per each stacked body can be converged
(absorbed) by increasing or decreasing the number of the spacer
sheets used.
[0071] By arranging the spacer member 40 selected in the
above-described manner in addition to the constituent elements of
the stacked body 24 (for example, the spacer member 40 is set
between the cooling plate 11 and end plate 18 at the right end of
the stacked body 24), it is possible to adjust adequately the
stacking direction length of the body 20 to be bundled (has a
configuration obtained by adding the spacer member 40 to the
stacked body 24). The body 20 to be bundled is then bundled by
wrapping around the bundling band 21 so as to create the stipulated
bundling pressure P. Because the stacking direction thickness of
the body 20 to be bundled is matched with the target value L0, the
body 20 to be bundled can be adequately bundled by using the
bundling band 21 of the same size (size corresponding to the
stacking direction length LT), regardless of the stacking direction
length L1 of the stacked body 24. The battery assembly 10 having
the stipulated bundling pressure P and stipulated stacking
direction length LT can thereafter be manufactured with good
stability by connecting the positive electrode terminals 15 and
negative electrode terminals 16 of the adjacent unit cells 12 with
the connection tools 17. Thus, with the present manufacturing
method, it is possible to provide with good efficiency the battery
assemblies 10 with the bundling pressure and stacking direction
length that are well matched.
[0072] In a case where the unit cell 12 has a configuration in
which the thickness can be easily changed (for example, the
thickness can be easily reduced by flexural deformation of the
container 14) by the pressure in the stacking direction (for
example, the pressure similar to the bundling pressure P), or in a
case where any of other constituent element (cooling plates 11, end
plates 18, 19) contained in the stacked body 24 can be easily
induced to change the thickness by the pressure in the stacking
direction, the stacking direction length L1 of the stacked body 24
may be measured in a state in which a compressive stress
(typically, a pressure corresponding to the bundling pressure P) is
applied in the stacking direction to the stacked body 24. As a
result, the stacking direction length obtained when the finally
obtained battery assembly 10 is bundled by the bundling pressure P
can be more accurately matched with the stipulated length LT.
[0073] In the example shown in FIG. 6, the spacer member 40 is
disposed at one outer side of the unit cell group, but the spacer
member 40 may be also inserted for example in an almost central
portion of the unit cell group. Further, in the example shown in
FIG. 6, all the components of the spacer member 40 (that is, the
three spacer sheets 42) are disposed together, but the spacer
sheets 42 may be also disposed separately in various portions of
the body 20 to be bundled.
[0074] Among the constituent elements for the body 20 to be
bundled, the arrangement order of the constituent elements
contained in the stacked body 24 (unit cells 12, cooling plates 11,
and end plates 18, 19) is preferably identical to the arrangement
order of the constituent elements of the stacked body 24 at the
time the stacking direction length L1 is measured. In such a case,
the battery assembly 10 having the stipulated bundling pressure P
and the stipulated stacking direction length LT can be manufactured
with better stability.
[0075] As shown in FIG. 5, instead of measuring the stacking
direction length L1 of the stacked body 24 in which the
predetermined number of unit cells 12, cooling plates 11, and end
plates 18, 19 are arranged, it is possible, for example, to measure
the stacking direction length L1 of the stacked body of unit cells
in which only the predetermined number of unit cells 12 are stacked
and adjust the thickness of the spacer member 40 according to the
stacking direction length L1. More specifically, for example, it is
possible to compare the stacking direction length L1 of the stacked
body of unit cells and the total thickness (can have a spread
reflecting the stacking direction length L1 of the stacked body of
unit cells) of the predetermined number of cooling plates 11 and
the end plates 18, 19 contained in the body 20 to be bundled, with
the target value L0 of the stacking direction length of the body 20
to be bundled, and to select the thickness of the spacer member 40
so as to converge the spread in the total thickness and compensate
the thickness of the target value L0. Such an approach can be
advantageously used in the case in which the spread in stacking
direction thickness of the cooling plates 11 and end plates 18, 19
is sufficiently small to be ignored. Further, the manufacturing
method of the present example can be also implemented in a mode in
which the stacking direction length L1 of the stacked body of only
the unit cells 12 is measured. Therefore, such a method can be also
advantageously applied to manufacturing a battery assembly 10 of a
configuration in which no cooling plates 11 are disposed between
the unit cells 12 (for example, a battery assembly in which cooling
air passages are formed between the adjacent unit cells 12 by using
convex grooves provided in the wide surface 14A of the container
14).
Example 2
[0076] In the present embodiment, length adjusting means of a
configuration different from that of the spacer member 40 in
Example 1 is used as length adjusting means for converging the
spread in stacking direction length L1 of the stacked body.
[0077] As shown schematically in FIG. 8, a battery assembly 10 of
the present example includes a unit cell group composed of a
predetermined number of unit cells 12 that have a structure similar
to that described in Example 1 and cooling plates 11 disposed
between the unit cells 12 and also at both outer sides in the
stacking direction of the unit cells, end plates 50, 19 disposed in
intimate contact with the cooling plates 11 arranged at both outer
side of the unit cell group, and a bundling band 21 that bundles a
body 20 to be bundled that is composed of the unit cell group and
the end plates 50, 19 in the stacking direction. The battery
assembly 10 is so configured that the body 20 to be bundled is
bundled by the stipulated bundling pressure P and the length in the
stacking direction is a stipulated length LT. A thickness adjusting
mechanism that adjusts the thickness of the plate 50 in the
stacking direction is provided in the end plate 50 disposed at one
end (right end in FIG. 8) of the unit cell group. The end plate
(length adjusting means) 50 of the present example includes two
parallel plate-shaped outer plate 52 and inner plate 54 and a bolt
56 that is provided through the outer plate 52 and connected by a
distal end thereof to the inner plate 54, and the end plate is
configured so that the distance between the plates 52, 54 can be
adjusted by the tightening degree of the bolt 56 (setscrew
mechanism). The configuration of other components is identical to
that of the battery assembly 10 of Example 1.
[0078] With the manufacturing method of the present example, the
battery assembly 10 having the above-described configuration is
manufactured in the following manner. Thus, as shown schematically
in FIG. 7, a stacked body (unit cell group) 25 is configured in
which the predetermined number of unit cells 12 and the cooling
plates 11 disposed between the unit cells 12 and at both outer
sides are arranged, and the stacking direction length L1 of the
stacked body 25 is measured. The sum total of the measured value
obtained (stacking direction length L1 of the stacked body 25) and
the thickness of the end plate 18 shown in FIG. 8 is compared with
a target value L0 of the stacking direction length of the body 20
to be bundled that has been set in advance (similarly to Example 1,
the target value L0 is set so as to configure a battery assembly of
a stipulated stacking direction length LT by bundling the body 20
to be bundled that has the stacking direction length L0 with the
stipulated bundling pressure P, therefore so as to realize the
stipulated bundling pressure P by wrapping around the bundling band
21 of a shape and size that enable the configuration of the battery
assembly with the stipulated length LT to the body 20 to be
bundled), and the thickness required for the end plate 50 to
compensate for the difference between the compared values is found.
In this case, similarly to Example 1, the stacking direction length
of the stacked body 25 has a spread reflecting the spread in
thickness of the unit cells 12 contained in the stacked body 25.
Therefore, the thickness of the end plate 50 is adjusted so as to
converge (absorb) this spread and obtain the battery assembly 10
having the stipulated bundling pressure P and stacking direction
length LT. The body 20 to be bundled is configured by arranging the
end plate 19 and the end plate 50 with the thickness adjusted
according to the measurement result of the length L1 at both outer
sides of the stacked body 25. The battery assembly 10 having the
stipulated bundling pressure P and stipulated stacking direction
length LT can be manufactured with good stability and efficiency by
bundling the body 20 to be bundled with the bundling band 21 and
then connecting the positive electrode terminals 15 and negative
electrode terminals 16 of the adjacent unit cells 12 with the
connection tools 17. Further, because the stacking direction length
of the bundled body 20 matches the target value L0, the body 20 to
be bundled can be adequately bundled by using the bundling band 21
of the same size, regardless of the spread in stacking direction
length L1 of the stacked body 25.
[0079] Instead of forming the body 20 to be bundled by using the
end plate 50 with a thickness adjusted in advance as described
hereinabove, it is also possible to form the body 20 to be bundled
by using the end plate 50 that has not been adjusted to the final
thickness (rough thickness adjustment may be performed to obtain a
thickness that is clearly less than the supposed necessary
thickness), bundle the body 20 to be bundled with the bundling band
21 so as to obtain the stacking direction length LT, and then match
the bundling pressure of the body 20 to be bundled with the
stipulated bundling pressure P by using the thickness adjusting
mechanism of the end plate 50 (in this case, by adjusting the
tightening degree of the bolt 56). The advantage of such an
approach is that the process of adjusting the tightening degree of
the bolt 56 can be conducted by a torque control.
Example 3
[0080] In the present embodiment, length adjusting means of a
configuration different from that of the spacer member 40 in
Example 1 is used as length adjusting means for converging the
spread in stacking direction length L1 of the stacked body.
[0081] As shown schematically in FIG. 9, a battery assembly 10 of
the present example includes a unit cell group composed of a
predetermined number of unit cells 12 that have a structure similar
to that described in Example 1 and cooling plates 11 disposed
between the unit cells 12 and also at both outer sides in the
stacking direction of the unit cells, a pair of end plates 18, 19
disposed further outside of the unit cell group, elastic members 62
disposed between the end plate 18 and the cooling plate 11 disposed
on one outer side (right end in FIG. 9) of the unit cell group, and
a bundling band 21 that bundles the aforementioned components (that
is, a body 20 to be bundled that is composed of the unit cell
group, end plates 18, 19, and elastic members 62). The
configuration of other components is identical to that of the
battery assembly 10 of Example 1.
[0082] With the manufacturing method of the present example, the
battery assembly 10 having the above-described configuration is
manufactured in the following manner. In other words, the stacking
direction length L1 of a stacked body 24 is measured, the stacked
body 24 being obtained by arranging, in the stacking direction, the
predetermined number of unit cells 12 and the cooling plates 11
that are used in the manufacture of the battery assembly 10 and
then disposing the end plates 18, 19 at both ends of the
arrangement thus obtained as shown schematically in FIG. 5. The
obtained measured value L1 is compared with a distance LD between
the inner ends of the bundling tool (in this case, a bundling band
21) that abuts against the body 20 to be bundled, where the
bundling tool is used so as to realize a stipulated length LT.
Further, as shown in FIG. 9, elastic members 62 are selected such
that have properties making it possible to converge (absorb) the
spread in stacking direction length L1 of the stacked body 24 and
demonstrate a repulsion force corresponding to the stipulated
bundling pressure P when the elastic members are compressed to a
thickness corresponding to a difference (LD-L1) between the
distance LD and the stacking direction length L1. The body 20 to be
bundled in which the elastic members 62 are arranged in addition to
the constituent elements of the stacked body 24 is bundled with the
bundling band 21 so as to obtain the stipulated stacking direction
length LT. Thus, the battery assembly 10 having the stipulated
bundling pressure P and stipulated stacking direction length LT can
be manufactured with good stability and efficiency. Further,
because the stacking direction length L1 of the stacked body 24 can
be absorbed to a degree of elastic deformation of the elastic
member 62, the body 20 to be bundled can be adequately bundled by
using the bundling band 21 of the same size, regardless of the
spread in length L1.
[0083] The configuration of the elastic member 62 is not
particularly limited. For example, a spring (plate spring, coil
spring, and the like) having the desired spring constant or an
elastic material (a molded body of a dense or porous structure that
is composed of an elastomer material such as rubber or urethane)
molded to a predetermined shape can be used. In the present
embodiment, a plate spring is used as the elastic member 62.
Example 4
[0084] In the present embodiment, an example is described in which
length adjusting means (length adjusting member) for absorbing the
spread in stacking direction length L1 of the stacked body and
adjusting the stacking direction length of the battery assembly is
disposed on the outside in the stacking direction of the body to be
bundled (that is, in a position in which no bundling pressure is
applied thereto).
[0085] As shown schematically in FIG. 10, the battery assembly 10
of the present example includes a unit cell group that is composed
of a predetermined number of unit cells 12 constructed in the same
manner as in Example 1 and cooling plates 11 disposed between the
unit cells 12 and at both outer sides in the stacking direction
thereof, a pair of end plates 18, 19 disposed further on the
outside of the unit cell group, a bundling band 21 that bundles the
body 20 to be bundled that is composed of the unit cell group and
the end plates 18, 19 in the stacking direction, and an externally
attached spacer 66 that is disposed on the outside in the stacking
direction of the body 20 to be bundled. The configuration of other
components is similar to those of the battery assembly 10 of
Example 1.
[0086] With the manufacturing method of the present example, the
battery assembly 10 having the above-described configuration is
manufactured in the following manner. Thus, as shown schematically
in FIG. 5, a predetermined number of unit cells 12 and cooling
plates 11 that are used in the manufacture of the battery assembly
10 are arranged in the stacking direction, end plates 18, 19 are
disposed at both side of this arrangement, and a stacking direction
length L1 of the stacked body 24 thus obtained is measured. Then,
as shown schematically in FIG. 10, the body 20 to be bundled is
bundled by the stipulated bundling pressure P by wrapping the
bundling band 21 of a size corresponding to the stacking direction
length L1 (that is, the size suitable to bundle the stacked body 24
having the stacking direction length L1 by the stipulated bundling
pressure P) around the body 20 to be bundled that is composed of
the stacked body 24. In this case, the spread in stacking direction
length of the stacked body 24 reflects the spread in thickness of
unit cells 12 contained in the stacked body 24. Therefore, the
stacking direction length B of the bundled unit that is obtained by
bundling the stacked body 24 by the bundling pressure P also has a
spread. Accordingly, the externally attached spacer 66 is selected
that has a stacking direction length necessary to converge (absorb)
the spread in stacking direction length B and match the stacking
direction length of the battery assembly 10 with the stipulated
length LT, and the selected spacer is attached on the outside in
the stacking direction of the member (that is, the body 20 to be
bundled) that is the object of bundling with the bundling band
shown in FIG. 10. In the example shown in FIG. 10, the externally
attached spacer 66 is fixed by screwing from the outside of the
bundling band 21 to the end plate 18 located at the right end of
the body 20 to be bundled. The externally attached spacer 66 may be
attached, for example, to the end portion of the bundling band
21.
[0087] Thus, the battery assembly 10 having the stipulated bundling
pressure P and stipulated stacking direction length LT can be
manufactured with good stability and efficiency. With the
manufacturing method of the present embodiment, the stacking
direction length of the battery assembly can be adjusted with good
accuracy, without applying the bundling pressure P to the
externally attached spacer 66. Further, because the externally
attached spacer 66 is not required to have a pressure withstand
strength (rigidity) against the bundling pressure P, the structure
and constituent material of the externally attached spacer 66 can
be selected from wider ranges (for example, a more suitable range
in terms of lightweight and cost).
Example 5
[0088] The configuration of a battery assembly 10 of the present
example is shown schematically in FIG. 11. The battery assembly 10
of the present example, includes a unit cell group including a
predetermined number of unit cells 12 constructed in the same
manner as in Example 1, a pair of end plates 18, 19 disposed
further on the outside of the unit cell group, and a bundling band
21 that bundles in the stacking direction a body 20 to be bundled
that is composed of the unit cell group and end plates 18, 19. In
this case, the unit cell group is composed of the predetermined
number of unit cells 12, cooling plates 11 that are disposed
between the unit cells 12 and at both outer sides thereof in the
stacking direction, and a plurality of spacing adjusting members 44
in the form of thin sheets. The battery assembly 10 is configured
so that the body 20 to be bundled is bundled by the stipulated
bundling pressure P, the stacking direction length of the battery
assembly 10 is a stipulated length LT, and a stacking pitch D of
the unit cells 12 is constant. The configuration of other
components is similar to those of the battery assembly 10 of
Example 1.
[0089] With the manufacturing method of the present example, the
battery assembly 10 having the above-described configuration is
manufactured in the following manner. Thus, individual thickness of
the predetermined number of unit cells 12 that will be used to
manufacture the battery assembly 10 is measured, and a total value
CT of the measured values is found. Further, the individual
thickness of cooling plates 11 used in the same battery assembly 10
in which the unit cells 12 will be used is measured (in a case
where the spread in thickness of the cooling plates 11 is small, a
designed value may be used instead of the actually measured value
of the thickness of the cooling plates 11), and a total value DT of
the thickness of these cooling plates 11 is found. Then, a value
obtained by adding the total value DT (total thickness of the
cooling plates 11) and the thickness of the end plates 18, 19 to
the total value CT (total thickness of the unit cells 12) is
compared with a target value L0 of the stacking direction length of
the body 20 to be bundled that has been set in advance (similarly
to Example 1, this target value is set such that the battery
assembly of the stipulated stacking direction length LT can be
configured by bundling the body 20 to be bundled with the stacking
direction length L0 by the stipulated bundling pressure P and
therefore such that the stipulated bundling pressure P can be
realized by wrapping around the body 20 to be bundled the bundling
band 21 of a shape and size that make it possible to configure the
battery assembly of the stipulated length LT). Then, a total
thickness FT of the spacing adjusting member 44 that is used to
construct the battery assembly 10 is found according to the total
value CT, more specifically, such that the spread in a sum total
value of the total value CT, total value DT, and thickness of the
end plates 18, 19 is converged (absorbed) and the difference with
the target value L0 is compensated. The spacing adjusting member 44
is formed in a thin plate shape of a predetermined thickness, and
the total thickness FT can be adjusted by changing the number of
the spacing adjusting members used. Usually, a plurality of spacing
adjusting members 44 are used for one battery assembly 10.
[0090] Then, the unit cells 12, cooling plates 11, end plates 18,
19, and a plurality of spacing adjusting members 44 having a total
thickness FT are arranged to form the body 20 to be bundled. In
this case, the plurality of spacing adjusting members 44 are
distributed in appropriate locations in the stacking direction of
the body 20 to be bundled so that the spread in thickness of the
two unit cells 12 that are disposed adjacently (and the spread of
thickness of cooling plates 11 disposed between these unit cells
12) is converged and the stacking pitch D of the unit cells 12 is
made even on the basis of results obtained in measuring the
thickness of individual unit cells 12 (preferably, also on the
basis of results obtained in measuring the thickness of cooling
plates 11). In the example shown in FIG. 11, the unit cell 12 (12A)
at the left end and the unit cell 12 (12B) disposed adjacently
thereto at the right side therefrom have an about intermediate
thickness from among the predetermined number of unit cells
constituting the battery assembly 10, and the cooling plate 11 and
one spacing adjusting member 44 are disposed between these unit
cells 12A, 12B. The unit cell 12 (12C) that is third from the left
end has a relatively large thickness due to a spread that has
occurred when the containers were manufactured. Therefore, only the
cooling plate 11 is disposed between the unit cell 12C and the
second unit cell 12B from the left, and no spacing adjusting member
44 is disposed therein. By contrast, in the configuration shown in
FIG. 11, the unit cell 12 (12E) at the right end and the unit cell
12 (12D) disposed adjacently thereto at the left side thereof both
have a comparatively small thickness. Therefore, two spacing
adjusting members 44 are disposed in addition to the cooling plate
11 between these unit cells 12D, E. Thus, the pitch (reflected in
the distance between the electrodes of the adjacent unit cells 12)
between the unit cells 12A, B, unit cells 12B, C, and unit cells
12D, E is made uniform. Because the stacking p-itch D of the unit
cells 12 is thus made uniform, with the configuration of the
present embodiment, the positive and negative electrode terminals
15, 16 between the adjacent unit cells 12 can be successively
connected by using the connection tools 17 of a single
predetermined shape. As a result, the battery assembly 10 can be
manufactured with good efficiency without conducting a complex
connection operation in which the distances between terminals 15,
16 are measured between individual unit cells 12 and the connection
tools corresponding to the measured distances are selected and used
(or using the connection tools having a mechanism that can adjust
the distance between the connection portions of two terminals of
positive and negative electrodes and the connection operation is
performed, while adjusting the distance between the connection
portions of the terminals).
[0091] A material identical to that of the spacer member 40
explained in Example 1 can be advantageously used as the structural
material of the spacing adjusting member 44. In the present
example, polypropylene sheets of the same thickness (typically, 10
.mu.m to 1000 .mu.m, preferably 100 .mu.m to 200 .mu.m) are used as
the spacing adjusting members 44.
[0092] In the explanation above, a value corresponding to the
center of the range of thickness rank is used as the representative
value of each thickness rank, but for example an average value of
the thicknesses of a plurality of unit cells 12 that belong to each
thickness rank may be also used as the representative value of the
thickness rank.
Example 6
[0093] A method for manufacturing a battery assembly of the present
embodiment will be explained below with reference to FIG. 12. Thus,
a stacking direction thickness is measured for each of a large
number of unit cells 12, and the large number of unit cells 12 are
classified into a plurality of thickness ranks with mutually
different thickness ranges according to the measurement results.
For example, as shown schematically in FIG. 12, the unit cell 12
for which the stacking direction thickness T is within a range (M-1
.mu.m.ltoreq.T.ltoreq.M+1 .mu.m) of the average value M.+-.1 .mu.m
of the measured values is classified into a thickness rank 2 for
which M is a representative value, the unit cell 12 for which the
stacking direction thickness T is within a range M-3
.mu.m.ltoreq.T<M-1 .mu.m is classified into a thickness rank 1
for which M-2 .mu.m is a representative value, and the unit cell 12
for which the stacking direction thickness T is within a range M+1
.mu.m<T.ltoreq.M+3 .mu.m is classified into a thickness rank 3
for which M+2 .mu.m is a representative value. The predetermined
number of unit cells contained in the battery assembly 10 are then
selected from the thickness ranks 1 to 3 in a combination such that
the sum total of the representative values of the thickness ranks
to which the unit cells belong is the stipulated thickness RT. The
stipulated thickness RT is set such that the sum total of the
thickness RT and the thickness of other constituent elements
constituting the body 10 to be bundled, that is, the predetermined
number of cooling plates 11 and end plates 18, 19 is the target
value L0 of the stacking direction thickness of the body 20 to be
bundled (similarly to Example 1, this target value is set such that
the battery assembly of the stipulated stacking direction length LT
is constituted by bundling the body 20 to be bundled that has the
stacking direction length L0 by the stipulated bundling pressure P
and therefore the stipulated bundling pressure P is realized by
wrapping around the body 20 to be bundled a bundling band 21 of a
shape and size that make it possible to configure the battery
assembly of the stipulated length LT).
[0094] The body 20 to be bundled is formed by arranging the
predetermined number of selected unit cells 12 alternately with the
cooling plates 11 and then disposing the end plates 18, 19 at both
ends. In this case, the predetermined number of unit cells 12 that
will be used is selected such that the spread is eliminated and the
total thickness of the unit cells converges to the stipulated
length RT, regardless of the spread in thickness of the unit cells
12 that will be used. As a result, the body 20 to be bundled is
configured such that the spread in stacking direction length is
reduced and the stacking direction length assumes the target value
L0. Therefore, by bundling the body 20 to be bundled with the
bundling band 21 so as to obtain the stipulated stacking direction
length LT, it is possible to manufacture the battery assembly 10
with the stipulated bundling pressure P and stipulated stacking
direction length LT with good stability and efficiency. Further,
the manufacturing method of the present example makes it possible
to decrease the rejection ratio of the unit cells 12 and reduce the
production cost of the battery assembly 10 by comparison, for
example, with a method in which only the unit cells 12
corresponding to the thickness rank 2 are used to manufacture the
battery assembly 10 and the unit cells 12 corresponding to the
thickness rank 1 (thin) and thickness rank 3 (thick) are rejected
as defective.
[0095] The predetermined number of cooling plates 11 contained in
the battery assembly 10 also can be classified in a similar manner
into a plurality of thickness ranks and the cooling plates 11 that
are adequately selected from these thickness ranks to obtain the
predetermined total thickness can be combined and used, thereby
making it possible to increase further the accuracy of the bundling
pressure P and stacking direction length LT of the battery assembly
10.
Example 7
[0096] A method for manufacturing a battery assembly of the present
embodiment will be explained below with reference to FIG. 13 and
FIG. 14.
[0097] Thus, a positive electrode sheet 32 is fabricated by forming
a positive electrode active material layer for a lithium ion
battery on an elongated positive electrode collector. For example,
a composition in which a material for forming a positive electrode
active material that has the positive electrode active material as
a main component is dispersed in an appropriate dispersion agent is
applied to body surfaces of a positive electrode collector (for
example, an aluminum foil) and dried. The configuration obtained is
pressed by squeezing between rolls 68 and then wound. This process
is repeated to fabricate a plurality of positive electrode rolls 33
in which the positive electrode sheet 32 of a length corresponding
to that necessary for a plurality of unit cells 12 is wound in a
roll. In this case, the thickness of the positive electrode sheet
32 after pressing is measured as the active material is pressed by
the rollers 68, and the plurality of positive electrode rolls 33
are classified based on the measured sheet thickness into a
plurality of thickness ranks with mutually different thickness
ranges. For example, as shown schematically in FIG. 13, the
positive electrode roll 33 for which the sheet thickness T is
within a range (M-0.1 .mu.m.ltoreq.T.ltoreq.M+0.1 .mu.m) of the
average value M.+-.0.1 .mu.m of the measured values is classified
into a thickness rank 2 for which M is a representative value, the
positive electrode roll 33 for which the stacking direction
thickness T is within a range M-0.3 .mu.m.ltoreq.T.ltoreq.M-0.1
.mu.m is classified into a thickness rank 1 for which M-0.2 .mu.m
is a representative value, and the positive electrode roll 33 for
which the stacking direction thickness T is within a range M+0.1
.mu.m.ltoreq.T.ltoreq.M+0.3 .mu.m is classified into a thickness
rank 3 for which M+0.2 .mu.m is a representative value.
[0098] Likewise, as shown in FIG. 14, a plurality of negative
electrode rolls 35 (obtained by winding into rolls the negative
electrode sheets of a length corresponding to that necessary for a
plurality unit cells 12) and separator rolls (obtained by winding
into rolls the separator sheets of a length corresponding to that
necessary for a plurality unit cells 12) 37 that have been
classified into respective thickness ranks 1 to 3 are prepared.
Then, the positive electrode sheet 32, negative electrode sheet 34,
and two separator sheets 36 for fabricating the wound electrode
body 30 to be included in each electrode cell 12 contained in the
battery assembly 10 are selected in combinations such that the sum
total of the representative values of thickness ranks to which
these sheets belong is the stipulated thickness ST. In the example
shown in FIG. 14, the positive electrode sheet 32 and negative
electrode sheet 34 are both selected from the thickness rank 2,
whereas one separator sheet is selected from the thickness rank 1
and the other from the thickness rank 3. The selected four sheets,
that is, the positive electrode sheet 32, first separator sheet 36,
negative electrode sheet 34, and second separator sheet 36 are
laminated in the order of description and wound. The wound body
obtained is flattened from the side surface direction, thereby
producing a flat-shaped wound electrode body 30 (see FIG. 3). In
this case, the four sheets used to fabricate the electrode body 30
are selected and combined so that the total thickness (lamination
thickness) ST of the representative values of thickness ranks to
which the sheets belong has a constant value. As a result, the
thickness spread among the individual sheets can be canceled and
wound electrode bodies 30 with the thickness well matched in the
flattening direction (small spread in thickness) can be
manufactured with good stability and efficiency.
[0099] Such a decrease in the spread in thickness of the wound
electrode bodies 30 makes it possible to reduce a spread in
thickness of unit cells in which the electrode body 30 is
accommodated in the container 14. By constructing a battery
assembly in which such unit cells with a small spread in thickness
are arranged in the stacking direction, it is possible to
manufacture a battery assembly having the stipulated stacking
direction length LT and bundling pressure P with good stability and
efficiency. The reduction of spread in thickness of electrode
bodies can demonstrate an especially significant effect when a
container is used that has a configuration or includes a material
such that the thickness can be easily changed by a pressure applied
in the stacking direction (for example, a pressure similar to the
bundling pressure P). Further, because using such unit cells with a
small spread in thickness makes it possible to match effectively
the stacking pitches D of the unit cells, the terminals of unit
cells can be connected with good efficiency by using connection
tools of the same predetermined shape, similarly to the battery
assembly of Example 5 and manufacturing method thereof. Measuring
the thickness as the positive electrode sheet 32 is manufactured,
as shown in FIG. 13, is preferred because the thickness measurement
step can be incorporated in the conventional process for
manufacturing the positive electrode sheet 32 (for example, a
pressing process) and implemented in an in-line mode and no novel
step has to be added to measure the thickness.
[0100] By using the unit cells with a small spread in thickness
that have been obtained by the method of the present example, a
battery assembly may be manufactured for example by the
above-described manufacturing methods of Examples 1 to 6. Thus, the
unit cells manufactured (prepared) by the method according to
Example 7 can be advantageously used as the unit cells 12 used in
the manufacturing methods of Examples 1 to 6. The battery assembly
having the stipulated stacking direction length LT and bundling
pressure P can thus be manufactured with even better accuracy.
[0101] The total thickness ST of the four aforementioned sheets can
be set to form an electrode body with a thickness suitable for
accommodation in the container with consideration for a distance in
the stacking direction inside the container (distance between the
inner walls of the opposing flat surfaces), a length of the sheets
used, and a winding diameter of the wound electrode body (before
flattening). The ST is preferably set such that no excessive gap
remains between the inner wall of the container and the flat
surface of the electrode body accommodated in the container and no
excessive bulging of the container is caused by the electrode body
contained therein.
Example 8
[0102] A method for manufacturing a battery assembly of the present
embodiment will be explained with reference to FIG. 15.
[0103] Thus, similarly to the electrode body 30 provided for a unit
cell 12 used in Example 1 (see FIG. 4), a flat-shaped wound
electrode body 30 is fabricated by laminating the elongated
positive electrode sheet, negative electrode sheet, and two
separator sheets, winding, and flattening the obtained wound body
from the side surface direction. In this case, a stacking direction
thickness F of the electrode body (electrode body of standard
configuration; can be referred to hereinbelow as "standard
electrode body") that is manufactured by the predetermined
conditions (inner diameter of the wound body, tension during
winding, number of winding turns, etc.) by laminating the
aforementioned sheets, that is, the length between the flat
surfaces of the electrode body, is predicted from the sheet
thickness of the positive electrode sheet, negative electrode
sheet, and separator sheets used to fabricate the electrode body
30. The stacking direction thickness F of the standard electrode
body can be predicted based on the past results obtained battery
assembly manufacture or can be readily found by preliminary
testing. Further, for example, similarly to Example 7, the
thickness of each sheet can be measured in an in-line mode by
incorporating a thickness measurement mechanism in the conventional
sheet manufacturing process (for example, electrode sheet pressing
process).
[0104] The stacking direction thickness F of the standard electrode
body is compared with a stacking direction thickness E of a
stipulated (target) electrode body, and the amount of the separator
sheet used is increased or decreased with respect to that in the
configuration of the standard electrode body so as to match the
thickness of the electrode body 30 that will be obtained with the
electrode body thickness E. For example, in a case in which the
stacking direction thickness F of the standard electrode body,
which is predicted from the thickness of each sheet used, is
somewhat larger than the target electrode body thickness E (this
can occur, for example, because the thickness of the positive
electrode sheet used is larger than the average value due to a
spread in thickness in the positive electrode sheet manufacturing
process) in the standard electrode body with a configuration in
which only the separator sheet is wound several times (for example,
2 to 3 turns) at the winding end of the electrode body 30, the
length of the separator sheet used is decreased and the number of
winding turns of the separator sheet at the winding end is reduced.
Conversely, in a case in which the stacking direction thickness F
of the standard electrode body, which is predicted from the
thickness of each sheet used, is somewhat smaller than the target
electrode body thickness E (this can occur, for example, because
the thickness of the negative electrode sheet used is smaller than
the average value due to a spread in thickness in the negative
electrode sheet manufacturing process), as in the example shown in
FIG. 15, the length of the separator sheet 36 used is increased and
the number of winding turns of the separator sheet 36 at the
winding end is increased. It is thus possible to manufacture the
wound electrode body 30 in which the thickness in the flattening
direction is well matched with the target electrode body thickness
E (small spread in thickness) with good stability and
efficiency.
[0105] Such a decrease in the spread in thickness of the wound
electrode bodies 30 makes it possible to reduce a spread in
thickness of unit cells in which the electrode body 30 is
accommodated in the container. By constructing a battery assembly
in which such unit cells with a small spread in thickness, it is
possible to manufacture a battery assembly having the stipulated
stacking direction length LT and bundling pressure P with good
stability and efficiency. The reduction of spread in thickness of
electrode bodies can demonstrate an especially significant effect
when a container is used that has a configuration or includes a
material such that the thickness can be easily changed by a
pressure applied in the stacking direction (for example, a pressure
similar to the bundling pressure P). Further, because using such
unit cells with a small spread in thickness makes it possible to
match effectively the stacking pitches D of the unit cells, the
terminals of unit cells can be connected with good efficiency by
using connection tools of the same predetermined shape, similarly
to the battery assembly of Example 5 and manufacturing method
thereof.
[0106] By using the unit cells with a small spread in thickness
that have been obtained by the method of the present example, a
battery assembly may be manufactured for example by the
above-described manufacturing methods of Examples 1 to 6. Thus, the
unit cells manufactured (prepared) by the method according to
Example 8 can be advantageously used as the unit cells 12 used in
the manufacturing methods of Examples 1 to 6. The battery assembly
having the stipulated stacking direction length LT and bundling
pressure P can thus be manufactured with even better accuracy.
[0107] The target electrode body thickness E can be set to obtain a
thickness suitable for accommodation in the container with
consideration for a distance between the inner walls of the
opposing flat surfaces of the container. The target thickness E is
preferably set such that no excessive gap remains between the inner
wall of the container and the flat surface of the electrode body
accommodated in the container and no excessive bulging of the
container is caused by the electrode body contained therein. In a
simple mode, for example, the distance between the inner walls can
be used as the target electrode body thickness E.
Example 9
[0108] A method for manufacturing a battery assembly of the present
embodiment will be explained below with reference to FIG. 16 and
FIG. 17.
[0109] Thus, similarly to the electrode body 30 provided for a unit
cell 12 used in Example 1, a flat-shaped wound electrode body 30 is
fabricated by laminating the elongated positive electrode sheet,
negative electrode sheet, and two separator sheets, winding, and
flattening the obtained wound body from the side surface direction.
A thickness G of the electrode body 30 thus obtained is measured
and compared with a stipulated value (target value) A of the
stacking direction thickness of a body 38 that will be accommodated
in a container 14. This body 38 to be accommodated is composed of
the electrode body 30 and one, or two or more gap filling sheets
(gas filling materials) 46 that are placed, if necessary, on the
flat surface of the electrode body 30 and accommodated together
with the electrode body 30 in the container 14. The stipulated
value A is set so as to obtain a thickness suitable for
accommodation in the container 14 with consideration for the
distance between the inner walls of the opposing flat surfaces of
the container 14. The stipulated value A is preferably set such
that no excessive gap remains between the inner wall of the
container 14 and the flat surface of the body 38 accommodated in
the container and no excessive bulging of the container 14 is
caused by the body 38 contained therein. In a simple mode, for
example, the distance between the inner walls can be used as the
target value A of the stacking direction thickness of the body 38
to be accommodated.
[0110] The desired number of the gap filling sheets 46 are then
placed on the flat surface of the electrode body 30 so that the
stacking direction thickness G (measured value) of the electrode
body 30 obtained is matched with the target value A. A material
similar to the spacer material 40 explained in Example 1 can be
advantageously used as the constituent material of the gap filling
sheets 46. In the present example, polypropylene sheets of the same
thickness (typically 10 .mu.m to 1000 .mu.m, preferably 100 .mu.m
to 200 .mu.m) are used as the gap filling sheets 46. In a case
where a plurality of the gap filling sheets 46 are used for one
electrode body 30, it is preferred that these gap filling sheets 46
be distributed as uniform as possible at both sides in the
lamination direction of the electrode body 30. Further, the
manufacturing conditions of the electrode body 30 may be adjusted
so that the maximum value (MAX value) of the stacking direction
thickness G of the electrode body 30 estimated from the thickness
spread of the positive electrode sheets, negative electrode sheets,
and separator sheets is the target value A (that is, so that the
desired number of gap filling sheets 46 is zero when the stacking
direction thickness G of the electrode body 30 is the MAX value
(=A)). FIG. 17 shows an example in which in the unit cell 12 (12B)
second from the left end and the unit cell 12 (12D) second from the
right end, two gap filling sheets 46 are disposed on the left and
right of the electrode body 30 of an average thickness, in the unit
cell 12 (12C) third from the left end, two gap filling sheets 46
are disposed on the right side and three on the left side (a total
of five sheets) of the thin electrode body 30, in the unit cell 12
(12A) on the left end, one gap filling sheet 46 is disposed on the
right side and two gap filling sheets are disposed on the left side
(a total of three sheets) of the thick electrode body 30, and in
the unit cell 12 (12E) on the right end, one gap filling sheet 46
is disposed on the left side and one on the right side of even
thicker electrode body 30.
[0111] Thus, by increasing and decreasing the number of the gap
filling sheets 46 used for each unit cell 12 according to the
measured value of the stacking direction thickness G of the
electrode body 30, it is possible to converge (absorb) the spread
in thickness G of the electrode bodies 30 and enable good matching
of the stacking direction thickness of the bodies 38 to be
accommodated with the target value A. As a result, the spread in
thickness of the unit cells 12 in which the body 38 is accommodated
in the container 14 can be reduced. By constructing the battery
assembly 10 by using such unit cells 12 with a small spread in
thickness, it is possible to manufacture the battery assembly 10
having the stipulated stacking direction length LT and bundling
pressure P with good stability and efficiency. The reduction of
spread in thickness of the bodies 38 to be accommodated can
demonstrate an especially significant effect when a container 14
that has a configuration or includes a material such that the
thickness can be easily changed by a pressure applied in the
stacking direction (for example, a pressure similar to the bundling
pressure P) is used as the container. Further, because using such
unit cells 12 with a small spread in thickness makes it possible to
match effectively the stacking pitches D of the unit cells 12, the
terminals of the unit cells 12 can be connected with good
efficiency by using connection tools 17 of the same predetermined
shape, similarly to the battery assembly of Example 5 and
manufacturing method thereof.
[0112] The configurations described herein by way of examples can
be used in appropriate combinations. For example, the battery
assembly 10 may be manufactured by the manufacturing methods of
Examples 1 to 6 by using the unit cells 12 with a small thickness
spread that have been obtained by the method of Example 9. Thus,
the unit cells 12 manufactured (prepared) by the method of Example
9 can be advantageously used as the unit cell 12 for use in the
manufacturing methods of Examples 1 to 6. The battery assembly 10
having the stipulated stacking direction length LT and bundling
pressure P can thus be manufactured with even better accuracy.
Further, Example 3 (configuration using an elastic member) may be
combined with Example 5 (configuration using a spacing adjusting
member). As a result, it is possible to obtain a constant stacking
pitch D of unit cells and realize the stipulated bundling pressure
P with high accuracy.
[0113] Further, in the above-described examples (e.g., Example 3),
the stacking direction length is measured with respect to the
electrode body including a total predetermined number (for example,
20) of unit cells constituting the battery assembly, but the number
of unit cells arranged during the measurements is not limited
thereto and may be the number that can allow (converge) the
dimensional spread. For example, the stacking direction length may
be measured for some (for 5, for 10, etc.) of the unit cells
constituting the battery assembly. The methods for manufacturing a
battery assembly that are disclosed herein can include such as an
aspect.
[0114] Several preferred embodiments of the battery assembly
manufacturing method in accordance with the present invention and
the battery assemblies that can be manufactured by these methods
are explained hereinabove in detail, but the present invention is
not intended to be limited to these specific embodiments.
[0115] For example, in the above-described embodiments, the
electrode body 30 is accommodated in the container 14 in an
orientation such that the winding axis of the wound electrode body
30 is a transverse direction (the direction in the thickness of
paper sheet in FIG. 2) of the unit cell 12, but the electrode body
30 may be also disposed so that the winding axis is the height
direction (up down direction in FIG. 2) of the unit cell 12.
Further, an electrode body of a laminated type in which a plurality
of positive electrode sheets and a plurality of positive electrode
sheets are alternately laminated together with separator sheets may
be used instead of the electrode bodies 30 of a wound type. The
invention disclosed herein can be advantageously applied to a
battery assembly in which a plurality of unit cells in which
electrode bodies having various configurations are accommodated in
containers (in particular, unit cells in which electrode bodies of
a wound type or a laminated type are accommodated in containers
with an orientation such that the sheets constituting the electrode
bodies are laminated in the stacking direction of the unit cells)
are arranged in the stacking direction.
[0116] Further, the type of unit cells constituting the battery
assembly is not limited to the above-described lithium ion battery,
and the unit cells may be batteries of various contents that differ
in the electrode body constituent material or electrode, for
example, lithium secondary batteries that use metallic lithium or a
lithium alloy as a negative electrode, nickel hydrogen batteries,
nickel cadmium batteries, and electric double layer capacitors.
[0117] The battery assembly 10 shown in FIG. 1 has a simple
configuration in order to explain the present invention, but it is
obvious to a person skilled in the art that a variety of
modifications or additional installations can be made without
departing from the scope of features and effect of the present
invention. For example, in a case of installation on a vehicle such
as an automobile, an external cover for protecting the main
components (unit cell group, etc.) of the battery assembly, a part
for fixing the battery assembly to the predetermined site of the
vehicle, and a part for joining a plurality of battery assembled
(battery modules) to each other can be installed, and the presence
or absence of such installations does not affect the technical
scope of the present invention.
INDUSTRIAL APPLICABILITY
[0118] The battery assembly in accordance with the present
invention can be advantageously used as a power source for a motor
(electric motor) installed on a vehicle such as an automobile.
Therefore, the present invention provides a vehicle (typically, an
automobile, in particular an automobile equipped with an electric
motor, such as a hybrid vehicle, an electric vehicle, and a fuel
cell vehicle) 1 provided with this battery assembly 10 as a power
source as shown schematically in FIG. 18.
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