U.S. patent application number 12/791641 was filed with the patent office on 2010-09-23 for laminate cell, assembled battery, battery module and electric vehicle.
This patent application is currently assigned to Nissan Motor Co., Ltd.. Invention is credited to Takaaki Abe, Yasunari Hisamitsu, Hideaki Horie, Takanori Ito, Takamitsu Saito, Osamu Shimamura, Hiroshi Sugawara.
Application Number | 20100239902 12/791641 |
Document ID | / |
Family ID | 31884679 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100239902 |
Kind Code |
A1 |
Hisamitsu; Yasunari ; et
al. |
September 23, 2010 |
LAMINATE CELL, ASSEMBLED BATTERY, BATTERY MODULE AND ELECTRIC
VEHICLE
Abstract
A laminate cell comprises a power generating element formed by
sequentially stacking positive electrode plates and negative
electrode plates while interposing separators therebetween; a
positive tab connected to the positive electrode plates through a
plurality of positive leads; a negative tab connected to the
negative electrode plates through a plurality of negative leads;
and a cell package formed of a metal composite film, the cell
package hermetically sealing the power generating element and an
electrolyte. According to the laminate cell, the heat capacity of a
portion of the positive tab, onto which a plurality of the positive
leads are joined, and the heat capacity of a portion of the
negative tab, onto which a plurality of the negative leads are
joined, are made larger than that of other portions of the positive
tab and the negative tab.
Inventors: |
Hisamitsu; Yasunari;
(Yokosuka-shi, JP) ; Abe; Takaaki; (Yokosuka-shi,
JP) ; Ito; Takanori; (Zushi-shi, JP) ;
Shimamura; Osamu; (Yokohama-shi, JP) ; Saito;
Takamitsu; (Yokohama-shi, JP) ; Horie; Hideaki;
(Yokosuka-shi, JP) ; Sugawara; Hiroshi;
(Yokosuka-shi, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
Nissan Motor Co., Ltd.
Kanagawa-ken
JP
|
Family ID: |
31884679 |
Appl. No.: |
12/791641 |
Filed: |
June 1, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10640029 |
Aug 14, 2003 |
|
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12791641 |
|
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Current U.S.
Class: |
429/161 |
Current CPC
Class: |
Y10T 29/49108 20150115;
Y02E 60/10 20130101; H01M 10/0431 20130101; H01M 10/0463 20130101;
H01M 50/10 20210101; H01M 50/557 20210101; Y10T 29/4911 20150115;
H01M 50/116 20210101; H01M 10/0413 20130101; H01M 50/531
20210101 |
Class at
Publication: |
429/161 |
International
Class: |
H01M 2/26 20060101
H01M002/26 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 26, 2002 |
JP |
P2002-245539 |
Claims
1-10. (canceled)
11. A laminate cell, comprising: a power generating element formed
by sequentially stacking positive electrode plates and negative
electrode plates while interposing separators therebetween; a
positive tab connected to the positive electrode plates through a
plurality of positive leads; a negative tab connected to the
negative electrode plates through a plurality of negative leads;
and a cell package formed of a metal composite film, the cell
package hermetically sealing the power generating element and an
electrolyte, wherein a resin having a larger heat capacity per unit
weight than that of the positive tab and the negative tab is
provided on a portion where the positive and negative leads are
connected to the positive and negative tabs, respectively, so that
a heat capacity of the portions where the positive and negative
leads are connected is made larger than that of the other portions
thereof.
12. A laminate cell according to claim 11, wherein the resin
comprises polyolefin.
13. A laminate cell according to claim 12, wherein the resin
comprises a composite material including: polyolefin; and either
metal particles or ceramic particles.
14. A laminate cell according to claim 12, wherein the resin
comprises a composite material including: polyolefin; and a phase
change material which absorbs heat by a phase change, the phase
change material being in a state of at least either microparticles
or microcapsules.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a laminate cell having a
structure, in which pluralities of positive and negative electrode
plates are alternately stacked while interposing separators
therebetween to configure a power generating element, and the
positive and negative electrode plates of the power generating
element are connected to positive and negative tabs through
pluralities of positive and negative leads, respectively. The
present invention also relates to an assembled battery, a battery
module and an electric vehicle, all of which use this laminate
cell.
[0003] 2. Description of the Related Art
[0004] In recent years, an electric vehicle which uses electricity
as a power source and a hybrid car which runs by a combination of
an engine and a motor have attracted attention due to the global
problem of environmental air pollution caused by automobile exhaust
gas. Thus, the development of a high-power battery to be mounted in
these types of vehicles, which achieves high energy/power
densities, occupies an important position in the industry.
[0005] Regarding this type of high-power battery, for example,
there is a lithium ion battery. Specifically, among this type of
battery, there is a laminate cell formed by stacking flat positive
and negative electrode plates upon one another while interposing
separators therebetween.
[0006] As for this laminate cell, one disclosed in Japanese Patent
Application Laid-Open No. 2000-200585 has been proposed, which
uses, as a cell package, a laminate film formed by stacking a metal
film and a polymer film. In this specification, the laminate film
is referred to as a metal composite film. This laminate cell is
constructed in a such manner that a power generating element
composed of positive and negative electrode plates and separators,
all of which have an approximately rectangular flat shape, are
hermetically sealed together with an electrolyte by the cell
package made of the metal composite film, and a positive tab
connected to the positive electrode plates of the power generating
element and a negative tab connected to the negative electrode
plates thereof are drawn outward from the end edges of the cell
package.
[0007] The laminate cell thus constructed has an advantage in that
it is easier to reduce the weight and thickness thereof in
comparison with one which uses a metal can as the cell package.
[0008] Incidentally, in the laminate cell thus constructed, it is
common that the respective positive electrode plates of the power
generating element are connected to the positive tab through
positive leads, and the respective negative electrode plates
thereof are connected to the negative tab through negative leads.
Specifically, in this type of laminate cell, one end of the
positive tab is drawn to the outside of the cell package, and onto
the other end thereof, the plurality of positive leads from the
respective positive electrode plates of the stacked electrode are
joined. Moreover, one end of the negative tab is drawn to the
outside of the cell package, and onto the other end thereof, the
plurality of negative leads from the respective negative electrode
plates of the stacked electrode are joined.
SUMMARY OF THE INVENTION
[0009] However, in the laminate cell as described above, heat
generated when a large current is carried therethrough tends to
concentrate in the other ends of the positive and negative tabs,
and the temperatures of the other ends of these positive and
negative tabs sometimes increase to a great extent. Thus, when the
temperatures of the other ends of these positive and negative tabs
are increased to an excessive extent, it is assumed that, due to
the heat generated at the positive and negative tabs, the polymer
film within the metal composite film constituting the cell package
is melted, the metal film is exposed, and a short circuit occurs
between this metal film and the positive or negative tab, or
between the metal film and the positive or negative leads.
[0010] The present invention was made in consideration of the
above-described problems. It is an object of the present invention
to provide a highly reliable laminate cell which avoids the problem
of an occurrence of a short circuit between the metal film of the
metal composite film for use in the cell package and the positive
or negative tab, or between the metal film and the positive or
negative leads, and to provide an assembled battery, a battery
module and an electric vehicle, all of which use this laminate
cell.
[0011] The first aspect of the present invention provides a
laminate cell, comprising: a power generating element formed by
sequentially stacking positive electrode plates and negative
electrode plates while interposing separators therebetween; a
positive tab connected to the positive electrode plates through a
plurality of positive leads; a negative tab connected to the
negative electrode plates through a plurality of negative leads;
and a cell package formed of a metal composite film, the cell
package hermetically sealing the power generating element and an
electrolyte, wherein a heat capacity of a portion of the positive
tab, onto which a plurality of the positive leads are joined, and a
heat capacity of a portion of the negative tab, onto which a
plurality of the negative leads are joined, are made larger than
that of other portions of the positive tab and the negative
tab.
[0012] The second aspect of the present invention provides a
laminate cell, comprising: a power generating element formed by
sequentially stacking positive electrode plates and negative
electrode plates while interposing separators therebetween; a
positive tab connected to the positive electrode plates through a
plurality of positive leads; a negative tab connected to the
negative electrode plates through a plurality of negative leads;
and a cell package formed of a metal composite film hermetically
sealing the power generating element and an electrolyte, wherein
insulating tapes having an electrical insulating property are
adhered to a portion of the positive tab, onto which the plurality
of positive leads are joined, and a portion of the negative tab,
onto which the plurality of negative leads are joined.
[0013] The third aspect of the present invention provides an
assembled battery, comprising: a single cell including a power
generating element formed by sequentially stacking positive
electrode plates and negative electrode plates while interposing
separators therebetween; a positive tab connected to the positive
electrode plates through a plurality of positive leads; a negative
tab connected to the negative electrode plates through a plurality
of negative leads; and a cell package formed of a metal composite
film, the cell package hermetically sealing the power generating
element and an electrolyte, wherein a heat capacity of a portion of
the positive tab, onto which a plurality of the positive leads are
joined, and a heat capacity of a portion of the negative tab, onto
which a plurality of the negative leads are joined, are made larger
than that of other portions of the positive tab and the negative
tab, and the assembled battery is formed by interconnecting any of
a plurality of the single cells and a plurality of single cell
groups electrically in series, each of the single cell group being
formed by interconnecting a plurality of the single cells
electrically in parallel.
[0014] The fourth aspect of the present invention provides a
battery module, comprising: an assembled battery having a single
cell including a power generating element formed by sequentially
stacking positive electrode plates and negative electrode plates
while interposing separators therebetween; a positive tab connected
to the positive electrode plates through a plurality of positive
leads; a negative tab connected to the negative electrode plates
through a plurality of negative leads; and a cell package formed of
a metal composite film, the cell package hermetically sealing the
power generating element and an electrolyte, wherein a heat
capacity of a portion of the positive tab, onto which a plurality
of the positive leads are joined, and a heat capacity of a portion
of the negative tab, onto which a plurality of the negative leads
are joined, are made larger than that of other portions of the
positive tab and the negative tab, the assembled battery is formed
by interconnecting any of a plurality of the single cells and a
plurality of single cell groups electrically in series, each of the
single cell group being formed by interconnecting a plurality of
the single cells electrically in parallel, and the battery module
is formed by electrically interconnecting a plurality of the
assembled batteries and housing the plurality of electrically
interconnected assembled batteries in a module case.
[0015] The fifth aspect of the present invention provides An
electric vehicle, comprising: a battery module comprising: an
assembled battery having a single cell including a power generating
element formed by sequentially stacking positive electrode plates
and negative electrode plates while interposing separators
therebetween; a positive tab connected to the positive electrode
plates through a plurality of positive leads; a negative tab
connected to the negative electrode plates through a plurality of
negative leads; and a cell package formed of a metal composite
film, the cell package hermetically sealing the power generating
element and an electrolyte, wherein a heat capacity of a portion of
the positive tab, onto which a plurality of the positive leads are
joined, and a heat capacity of a portion of the negative tab, onto
which a plurality of the negative leads are joined, are made larger
than that of other portions of the positive tab and the negative
tab, the assembled battery is formed by interconnecting any of a
plurality of the single cells and a plurality of single cell groups
electrically in series, each of the single cell group being formed
by interconnecting a plurality of the single cells electrically in
parallel, the battery module is formed by electrically
interconnecting a plurality of the assembled batteries and housing
the plurality of electrically interconnected assembled batteries in
a module case, and the battery module is used as a power source of
a driving motor driving drive wheels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will now be described with reference to the
accompanying drawings wherein;
[0017] FIG. 1 is a plan view illustrating an example of a laminate
cell according to the present invention;
[0018] FIG. 2 is a cross sectional view taken on line II-II of FIG.
1;
[0019] FIG. 3 is an enlarged cross-sectional view of portion III in
FIG. 2;
[0020] FIG. 4 is a substantially enlarged cross-sectional view
illustrating another example of the laminate cell according to the
present invention;
[0021] FIG. 5 is a substantially enlarged cross-sectional view
illustrating another example of the laminate cell according to the
present invention;
[0022] FIG. 6 is a side view illustrating an example of an
assembled battery according to the present invention;
[0023] FIG. 7 is a side view illustrating another example of the
assembled battery according to the present invention;
[0024] FIG. 8 is a plan view illustrating a battery module
according to the present invention; and
[0025] FIG. 9 is a block diagram schematically illustrating a drive
source of an electric vehicle according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Hereinafter, description will be made of embodiments of the
present invention with reference to the drawings.
First Embodiment
[0027] As illustrated in FIGS. 1 and 2, a laminate cell of this
embodiment includes stacked electrodes 2 as a power generating
element. The stacked electrode 2 is located at the center between a
pair of metal composite films 3a and 3b constituting the cell
package 3, and is hermetically sealed together with an electrolyte
so as to be sandwiched between the pair of metal composite films 3a
and 3b in the thickness direction.
[0028] As illustrated in FIG. 2, the stacked electrode 2 as the
power generating element is formed by sequentially stacking the
pluralities of positive and negative electrode plates 2A and 2B
while interposing the separators 2C therebetween. The respective
positive electrode plates 2A constituting the stacked electrodes 2
are connected to the positive tab 5 (electrode terminal) through
the positive leads 4. Moreover, the respective negative electrode
plates 2B constituting the stacked electrodes 2 are connected to
the negative tab 7 (electrode terminal) through the negative leads
6.
[0029] Each of the positive and negative leads 4 and 6 is formed of
metal foil. Specifically, the positive leads 4 are made of aluminum
foil, and the negative leads 6 are formed of copper foil. Then, the
positive leads drawn from the positive electrode plates 2A are
layered and joined onto the positive tab 5 using a technique such
as welding. Moreover, the negative leads 6 drawn from the negative
electrode plates 2B are layered and joined onto the negative tab 7
using a technique such as welding.
[0030] Each of the positive and negative tabs 5 and 7 is formed of
a metal plate. Specifically, for example, the positive tab 5 is
formed of an aluminum plate, and the negative tab 7 is formed of a
nickel plate. Then, one ends of the positive and negative tabs 5
and 7 are drawn outside the cell package 3 and are defined as
positive and negative terminals, respectively. Onto the other ends
located in the inside of the cell package 3, the plurality of
positive leads 4 drawn from the positive electrode plates 2A and
the plurality of negative leads 6 drawn from the negative electrode
plates 2B are layered and joined individually.
[0031] As illustrated in FIG. 3, in the laminate cell 1 of this
embodiment, the thickness T1 of the other end (hereinafter,
referred to as "junction portion 5a") of the positive tab 5, onto
which the plurality of positive leads 4 are layered and joined, is
made larger than the thickness T2 of the other portion of the
positive tab 5. In addition, the thickness of the other end
(hereinafter, referred to as "junction portion 7a") of the negative
tab 7, onto which the plurality of negative leads 6 are layered and
joined, is made larger than the thickness of the other portion of
the negative tab 7 in a similar way. The thicknesses of the
junction portions 5a and 7a are made larger, and thus the heat
capacities of these junction portions 5a and 7a can be increased,
and the temperature increase in the positive and negative tabs 5
and 7 can be controlled even when a large current is carried
therethrough.
[0032] Specifically, since heat is concentrated in the junction
portions 5a and 7a of the positive and negative tabs 5 and 7, the
temperatures of the positive and negative tabs 5 and 7 are prone to
increase when a large current is carried therethrough. However, in
the laminate cell 1 of this embodiment, the thicknesses of these
junction portions 5a and 7a are made larger when compared to the
other portions' thicknesses, and an increase of the heat capacities
thereof is achieved. Therefore, the temperature increase of the
positive and negative tabs 5 and 7 can be effectively
controlled.
[0033] Note that a method for increasing the thicknesses of the
junction portions 5a and 7a so as to be larger than those of the
other portions is not particularly limited. For example, when metal
plates serving as these positive and negative tabs 5 and 7 are
formed, the plates may be formed so as to be partially thick, and
thickly formed portions may be defined as junction portions 5a and
7a. In addition, metal paste may be partially coated on flat metal
plates to increase the thicknesses of portions coated therewith,
and these portions may be defined as junction portions 5a and
7a.
[0034] As illustrated in FIG. 3, for example, each of the pair of
metal composite films 3a and 3b constituting the cell package 3 is
formed in the manner described below. The metal layer 8 made of
aluminum or the like is used as a base material, the resin layer 9
made of polyethylene (PE), polypropylene (PP) or the like is coated
on the inside surface of the metal layer 8, and a protection layer
(not shown) such as nylon is adhered onto the outside surface of
the metal layer. The metal composite film 3a of the pair of metal
composite films 3a and 3b is formed into a cup shape, in which the
concave portion 10 housing the stacked electrode 2 is provided on
the center portion. The metal composite film 3b is formed flat so
as to cover the opening portion of the concave portion 10.
[0035] When the laminate cell 1 is fabricated, the stacked
electrode 2 is housed together with the electrolyte in the concave
portion 10 provided in the metal composite film 3a, and the flat
metal composite film 3b is disposed so as to cover the concave
portion 10, followed by heat sealing of the outer circumferential
portions of the pair of metal composite films 3a and 3b. Thus, a
structure is made, in which the stacked electrode 2 is hermetically
sealed together with the electrolyte by the cell package 3.
[0036] As described above, in the laminate cell 1 thus configured,
an increase in the heat capacities of the junction portions 5a and
7a upon which heat is prone to be concentrated when a large current
is carried therethrough is achieved, so that the temperature
increase of the positive and negative tabs 5 and 7 is controlled.
Therefore, high reliability, even when a large current is carried,
is ensured.
[0037] Specifically, with regard to the laminate cell 1 of
conventional technology, when the temperatures of the positive and
negative tabs 5 and 7 are excessively increased, it can be assumed
that, due to the heat generated in the positive and negative tabs,
the resin layers 9 of the metal composite films 3a and 3b are
melted, the metal layers 8 thereof are exposed, and a short circuit
occurs between the metal layers 8 and the positive or negative tab
5 or 7, or the positive or negative leads 4 or 6 because the metal
composite films 3a and 3b are used for the cell package 3. However,
in the laminate cell 1 of this embodiment, the thicknesses of the
junction portions 5a and 7a are increased so as to be larger than
those of the other portions, and thus the heat capacities of these
junction portions are increased, and the excessive temperature
increase of the positive and negative tabs 5 and 7 is effectively
controlled. Therefore, the problems as described above can be
avoided, and high reliability can be ensured.
[0038] The increase of the entire thicknesses of the positive and
negative tabs 5 and 7 is also considered as a method for
controlling the temperature increase of the positive and negative
tabs 5 and 7. However, in this case, it becomes difficult to ensure
the sealing capability on the edges of the cell package 3, from
which the positive and negative tabs 5 and 7 are drawn to the
outside, sometimes leading to the lowering of durability. On the
contrary, in the laminate cell 1 of this embodiment, only the
thicknesses of junction portions 5a and 7a of the positive and
negative tabs 5 and 7, upon which heat is most concentrated, are
made larger. Thus, control of the temperature increase of the
positive and negative tabs 5 and 7 is achieved. Accordingly, the
above-mentioned problem of the short circuit can be avoided, while
maintaining the sealing capabilities on the edges of the cell
package 3, and both durability and reliability can be ensured.
[0039] The laminate cell 1 of the present embodiment can be
employed as a lithium ion secondary battery. Hereinafter, the
materials of the lithium ion battery are additionally
explained.
[0040] As a positive electrode active material forming the positive
electrode plate 2A of the stacked electrode 2, a compound is
contained that includes lithium nickel composite oxides, in
particular, compounds expressed by a general formula
LiNi.sub.1-xM.sub.xO.sub.2. Here, x lies in a range of
0.01.ltoreq.x.ltoreq.0.5, and M represents at least one element
selected from iron (Fe), cobalt (Co), manganese (Mn), copper (Cu),
zinc (Zn), aluminum (Al), tin (Sn), boron (B), gallium (Ga),
chromium (Cr), vanadium (V), titanium (Ti), magnesium (Mg), calcium
(Ca) and strontium (Sr).
[0041] Further, the positive electrode may contain positive
electrode active material other than the lithium nickel composite
oxides. This material may include lithium manganese composite
oxides that form compounds expressed by a general formula
Li.sub.yMn.sub.2-zM'.sub.zO.sub.4. Here, y lies in a range of
0.9.ltoreq.y.ltoreq.1.2 while z lies in a range of
0.01.ltoreq.z.ltoreq.0.5, and M' represents at least one element
selected from Fe, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, V, Ti, Mg, Ca
and Sr. Alternately, this material may include lithium cobalt
composite oxides that form compounds expressed by a general formula
LiCo.sub.1-xM''.sub.xO.sub.2. Here, x lies in a range of
0.01.ltoreq.x.ltoreq.0.5, and M'' represents at least one element
selected from Fe, Ni, Mn, Cu, Zn, Al, Sn, B, Ga, Cr, V, Ti, Mg, Ca
and Sr.
[0042] Although there are no particular limitations in the
manufacturing methods of the lithium nickel composite oxides, the
lithium manganese composite oxides and the lithium cobalt composite
oxides, these compounds may be obtained by mixing carbonates such
as lithium, nickel, manganese and cobalt at ratios depending on
constituents thereof and baking these carbonates in a temperature
ranging from 600.degree. C. to 1000.degree. C. Also, the starting
materials may not be limited to the carbonates and can also be
similarly synthesized from hydroxides, oxides, nitrates and organic
acid salts.
[0043] Also, the positive electrode material such as the lithium
nickel composite oxides and the lithium manganese composite oxides
should preferably have an average particle size of 30 .mu.m or
below.
[0044] Further, the negative electrode plate 2B of the stacked
electrode 2 is formed of the negative electrode active material
with a specific surface area in a range from 0.05 m.sup.2/g to 2
m.sup.2/g. As a result of the negative electrode material with the
specific surface area of the above range, it is possible to
adequately restrict an excessive amount of a solid electrolyte
interface layer (SEI layer) from being formed on the negative
electrode surface.
[0045] With the negative electrode active material having a
specific surface area of less than 0.05 m.sup.2/g, since the area
available for lithium ions to transfer is extremely small, the
lithium ions doped into the negative electrode active material
during the charging cycle become too hard to be sufficiently doped
out from the negative electrode active material during the
discharging cycle, resulting in deterioration in the charging and
discharging efficiency. Conversely, with the negative electrode
active material having a specific surface area of greater than 2
m.sup.2/g, it is difficult to control an excessive amount of the
SEI layer from being formed on the negative electrode surface.
[0046] The negative electrode active material may include any
material that allows the lithium ions to be doped into or out of
the material at a voltage versus lithium of less than 2.0 volts.
More particularly, carbonaceous materials may be used which involve
a non-graphitizable carbon material, artificial graphite, natural
graphite, pyrolytic graphite, cokes including pitch coke, needle
coke and petroleum coke, graphite, glassy carbon, a sintered
material of polymers formed by baking and carbonizing phenol resin
or furan resin at an appropriate temperature, carbon fiber,
activated carbon and carbon black.
[0047] Further, a metal, that is able to form an alloy with
lithium, and an alloy thereof can also be used and, in particular,
these materials include oxide products or nitride products, that
allow the lithium ions to be doped into or out of the material at a
relatively low voltage potential, such as iron oxide, ruthenium
oxide, molybdenum oxide, tungsten oxide, tin oxide and main group
elements of group 13. In addition thereto, these materials include
elements such as silicon (Si) and tin (Sn), or alloys of Si and Sn
represented by a formula M.sub.XSi and M.sub.xSn (wherein M
represents more than one metallic element except for Si or Sn).
Among these, it is particularly preferable for Si or the Si alloys
to be used.
[0048] Further, the electrolyte may include a liquid state, a
so-called electrolysis solution composed of electrolyte salts
dissolved in and adjusted in a non-aqueous solvent, polymer gel
electrolyte composed of the electrolyte salt dissolved in the
non-aqueous solvent which is retained in a polymer matrix, and
polymer electrolyte composed of the electrolyte salt dissolved in
the polymer.
[0049] When using the polymer gel electrolyte as the non-aqueous
electrolyte, the polymer to be used includes poly (vinylidene
fluoride) and polyacrylonitrile. Also, when using the polymer
electrolyte, a polymer of polyethylene oxide (PEO) may be used.
[0050] The non-aqueous solvent may include any kind of solvent if
it remains in a non-aqueous solvent heretofore used in a secondary
battery using such kinds of non-aqueous electrolyte. As the
non-aqueous solvent, propylene carbonate, ethylene carbonate,
1,2-dimethoxyethane, diethyl carbonate, dimethyl carbonate,
.gamma.-butyrolactone, tetrahydrofuran, 1,3-dioxolane,
4-methyl-1,3-dioxolane, diethylether, sulfolane, methyl sulfolane,
acetonitrile and propionitrile can be used. Also, these non-aqueous
solvents may be used as a single kind or in a mixture of more than
two kinds.
[0051] Particularly, the non-aqueous solvent should preferably
contain an unsaturated carbonate. Particularly, it is more
preferable for the non-aqueous solvent to contain vinylene
carbonate. The presence of the unsaturated carbonate contained as
the non-aqueous solvent enables an effect, derived in the negative
electrode active material from the property (a function of a
protective layer) of the SEI layer, to be obtained and it is
conceivable that an excessive discharging-resistant characteristic
is further improved.
[0052] Further, the unsaturated carbonate should be preferably
contained in the electrolyte in a range from 0.05 wt % to 5 wt %
and, more preferably, in a range from 0.5 wt % to 3 wt %. With the
amount of content of the unsaturated carbonate being weighed in the
above range, a non-aqueous secondary battery is provided which has
a high initial discharging capacity with a high energy density.
[0053] The electrolyte salt may not be limited to a particular
composition provided that it forms a lithium salt presenting an ion
conductivity and may include LiClO.sub.4, LiAsF.sub.6, LiPF.sub.6,
LiBF.sub.4, LiB(C.sub.6H.sub.5).sub.4, LiCl, LiBr,
CH.sub.3SO.sub.3Li and CF.sub.3SO.sub.3Li. The electrolyte salt may
be used as a single kind or may be possibly used in a mixture of
more than two kinds.
[0054] The laminate cell 1 of the present invention has been
specifically described above in a case where the laminate cell 1 is
employed as the lithium ion secondary battery. However, the present
invention is not limited to the lithium ion secondary battery, and
can be applied to a cell having a similar constitution.
Second Embodiment
[0055] Next, another embodiment of the laminate cell to which the
present invention is applied will be described with reference to
FIG. 4.
[0056] As illustrated in FIG. 4, in the laminate cell 11 of this
embodiment, a structure is adopted, in which the positive tab 5 is
formed flat, and endothermic material 12 is provided on the
junction portion 5a of the positive tab 5, onto which the plurality
of positive leads 4 are joined. Moreover, though not shown, the
negative tab 7 is formed flat in a similar way. The endothermic
material 12 is provided on the junction portion 7a of the negative
tab 7, onto which the plurality of negative leads 6 are joined. The
laminate cell 11 is such that the endothermic material 12 is
provided on the junction portions 5a and 7a, and thus the heat
capacities of the junction portions 5a and 7a are increased, and it
is made possible to effectively control the temperature increase of
the positive and negative tabs 5 and 7. Other configurations of the
laminate cell 11 are similar to those of the above-mentioned
laminate cell 1 of the first embodiment, and therefore, in FIG. 4,
the same reference numerals are added to these similar portions,
and repeated description will be omitted.
[0057] In the laminate cell 11 of this embodiment, the endothermic
material 12 provided on the junction portions 5a and 7a is formed
by coating a resin having a larger heat capacity per unit weight
than those of the positive and negative tabs 5 and 7. As the resin
used for the endothermic material 12, for example, polyolefin is
listed. Polyolefin has a large heat capacity per unit weight among
resins, and is suitable for the endothermic material 12 in the
laminate cell 11 of this embodiment.
[0058] In the case of using polyolefin as the endothermic material
12 in the laminate cell 11 of this embodiment, this polyolefin may
be singly coated on the junction portions 5a and 7a to be used as
the endothermic material 12. In addition, other substances may be
contained in polyolefin to form a composite material, and this
composite material may be coated on the junction portions 5a and 7a
to be used as the endothermic material 12.
[0059] Specifically, for example, metal particles or ceramic
particles may be mixed into polyolefin to form a composite
material, and this composite material may be coated onto the
junction portions 5a and 7a to be used as the endothermic material
12. The metal particles and the ceramic particles have extremely
large heat capacities. Therefore, in the case of using the
composite material in which the metal or ceramic particles, as
described above, are mixed into polyolefin, the heat capacities of
the junction portions 5a and 7a can be further increased.
[0060] In addition, for example, a phase change material absorbing
heat by a phase change may be mixed as microparticle or
microcapsules into polyolefin to form the composite material, and
this composite material may be coated on the junction portions 5a
and the junction portion 7a to be used as the endothermic material
12. The phase change material exerts an endothermic function when a
phase change occurs following the temperature increase.
Accordingly, in the case of using the composite material in which
the phase change material as described above is mixed as
microparticles or microcapsules into polyolefin, the heat
capacities of the junction portions 5a and 7a can be further
increased. It is satisfactory for the preparation of the phase
change material into the microcapsules, to be performed by a known
method such as, for example, a method for forming a coating film by
coating appropriate microparticles on a solid phase change material
by means of an air suspension coating process.
[0061] As described above, in the laminate cell 11 thus configured,
endothermic material 12 is provided on the junction portions 5a and
7a on which heat is prone to be concentrated when a large current
is carried therethrough, the increase of the heat capacities of the
junction portions 5a and 7a is achieved, and the temperature
increase of the positive and negative tabs 5 and 7 is controlled.
Accordingly, high reliability, even when a large current is
carried, can be realized similarly to the above-mentioned laminate
cell 11 of the first embodiment.
[0062] In addition, in the laminate cell 11 of the embodiment,
resin having a larger heat capacity per unit weight in comparison
with those of the positive and negative tabs 5 and 7 is coated on
the junction portions 5a and 7a to be used as endothermic material
12. This is advantageous in reducing the entire weight of the
laminate cell 11.
Third Embodiment
[0063] Next, another embodiment of the laminate cell to which the
present invention is applied will be described with reference to
FIG. 5.
[0064] As illustrated in FIG. 5, in the laminate cell 13 of this
embodiment, a structure is made, in which the insulating tape 14
having an electrical insulating property is adhered to the junction
portion 5a of the positive tab 5, onto which the plurality of
positive leads 4 are joined, and to vicinities thereof. Moreover,
though not shown, the insulating tape 14 is adhered to the junction
portion 7a of the negative tab 7, onto which the plurality of
negative leads 6 are joined, and to vicinities thereof. Even if the
resin layer 9 of the metal composite film 3a constituting the cell
package 3 is melted and the metal layer 8 is exposed due to a
temperature increase of the positive and negative tabs 5 and 7, the
insulating tapes 14 are adhered to the junction portions 5a and 7a.
Accordingly, the metal layer 8 and the positive or negative tab 5
or 7, or the positive or negative lead 4 or 6 can be insulated by
the insulating tape 14, and the problem of the occurrence of a
short circuit therebetween can be avoided. Other configurations in
this laminate cell 13 are similar to those of the above-mentioned
laminate cell 1 of the first embodiment and laminate cell 11 of the
second embodiment. Therefore, in FIG. 5, the same reference
numerals are added to these similar portions, and repeated
description will be omitted.
[0065] In the laminate cell 13 of this embodiment, for the
insulating tape 14, any kind can be used, if a good electrical
insulating property can be obtained. For example, Kapton.RTM. tape
(polyimide tape) and the like are suitable. This type of insulating
tape 14 has excellent handling, and electrical insulation in the
portion to be insulated is obtained by adhering the insulating tape
14 thereto. The laminate cell 13 of this embodiment adopts a
structure, in which the insulating tapes 14 as described above are
adhered to the junction portions 5a and 7a. Accordingly, a
countermeasure against the case where the metal layer 8 of the
metal composite film 3a is exposed can be simply taken, without the
need for extra production work as regards the laminate cell 13.
[0066] The laminate cell 13 of this embodiment may be realized in a
form where the above-mentioned laminate cell 1 of the first
embodiment or laminate cell 11 of the second embodiment are
combined. Specifically, after increasing the thicknesses of the
junction portions 5a and 7a so as to be larger than those of the
other portions, the insulating tapes 14 may be further adhered to
the junction portions 5a and 7a. Moreover, after providing
endothermic material 12 on the junction portions 5a and 7a, the
insulating tapes 14 may be further adhered to the endothermic
materials 12. In these cases, a short circuit due to the
temperature increase of the positive and negative tabs 5 and 7 can
be more securely prevented, and further enhancement in reliability
can be realized.
Fourth Embodiment
[0067] Next, an assembled battery composed of the laminate cells to
which the present invention is applied will be described with
reference to FIGS. 6 and 7. FIG. 6 illustrates the assembled
battery 21 composed by interconnecting the plurality of single
cells 20 electrically in series, in which the laminate cells
(laminate cells 1, 10 or 13 mentioned above) to which the present
invention is applied are made as the single cells 20. Meanwhile,
FIG. 7 illustrates the assembled battery 23 composed by
interconnecting the plurality of single cell groups 22 electrically
in series, in which the plurality of single cells 20 are
interconnected electrically in parallel so as to make the single
cell groups 22.
[0068] The assembled battery 21 illustrated in FIG. 6 is formed by
stacking and integrating the plurality of single cells 20 in the
thickness direction. The respective single cells 20 constituting
the assembled battery 21 are stacked such that the directions of
the positive and negative tabs 5 and 7 of the adjacent single cells
20 alternate. With regard to a single cell 20 in which other single
cells 20 are stacked on both sides in the thickness direction,
respectively, the positive tab 5 of said single cell 20 is joined
to the negative tab 7 of one of the adjacent single cells 20 by a
technique such as ultrasonic bonding, and the negative tab 7
thereof is joined to the positive tab 5 of the other adjacent
single cell 20. In such a way, the positive and negative tabs 5 and
7 of all of the single cells 20 are joined to the negative and
positive tabs 7 and 5 of the adjacent single cells 20,
respectively, and thus the integrated assembled battery 21 in which
the respective single cells 20 are interconnected electrically in
series is composed.
[0069] Meanwhile, the assembled battery 23 illustrated in FIG. 7 is
composed by combining the single cell groups 22, each of which is
formed by interconnecting the plurality of single cells 20
electrically in parallel. The plurality of single cells 20 are
stacked such that the directions of the positive and negative tabs
5 and 7 of the adjacent single cells 20 is the same, and the
positive tabs 5 and negative tabs 7 of these single cells 20 are
individually interconnected by a technique such as the ultrasonic
bonding. Thus, the single cell groups constituting the assembled
battery 23 are formed by interconnecting the single cells 20
electrically in parallel. Then, the single cell groups 22 thus
constituted as aggregations of the plurality of single cells 20 are
stacked such that the directions of the positive and negative tabs
5 and 7 of the adjacent single cell groups 22 alternate. With
regard to a single cell group 22 in which other single cell groups
22 are layered on both sides in the thickness direction,
respectively, the positive tabs 5 of said single cell group 22 are
connected to the negative tabs 7 of one of the adjacent single cell
groups 22. Meanwhile, the negative tabs 7 of said single cell group
22 are connected to the positive tabs 5 of the other adjacent
single cell group 22. In such a way, the positive and negative tabs
5 and 7 of all of the single cell groups 22 are connected to the
negative and positive tabs 7 and 5 of the adjacent single cell
groups 22, respectively, and thus the integrated assembled battery
23 in which the respective single cell groups 22 are interconnected
electrically in series is composed.
[0070] Note that the number of single cells 20 constituting the
assembled batteries 21, 23 as described above is arbitrary, and it
is satisfactory to set the number appropriately in accordance with
the purpose of the concerned assembled batteries 21 and 23.
[0071] In the assembled batteries 21 and 23 thus constituted, the
plurality of single cells 20 are compactly identified, and
therefore, energy efficiency per unit volume is high. In this
connection, it is possible to apply the assembled batteries 21 and
23 to a variety of purposes. Particularly, as each of the single
cells 20 constituting the assembled batteries 21 and 23, the
laminate cell 1 or 11, in which the temperature increase in the
positive and negative tabs 5 and 7 can be controlled; and the
laminate cell 13, in which insulating tape is adhered to the
junction portions of the positive and negative tabs 5 and 7, are
used. Thus, high reliability, even when a large current is carried,
is ensured for each of the single cells 20. Therefore, the
assembled batteries 21 and 23 are suitable for, for example, use in
an electric vehicle regarding high power.
Fifth Embodiment
[0072] Next, an example of a battery module composed of the
assembled batteries 21 or 23 as described above will be described
with reference to FIG. 8. FIG. 8 illustrates the battery module 30
having a structure in which the plurality of assembled batteries 23
illustrated in FIG. 7 are interconnected electrically in series.
Note that the assembled batteries 21 constructed as illustrated in
FIG. 6 may also be used. In addition, the connection mode of the
plurality of assembled batteries is not limited to the serial
connection, but any mode including parallel connection,
parallel-serial connection, serial-parallel connection and the like
may be adopted. Moreover, the number of assembled batteries
constituting the battery module 30 is also arbitrary and may be
appropriately set in accordance with the purpose of the concerned
battery module 30.
[0073] The battery module 30 of this embodiment is constructed in
such a manner that the box-shaped module case 31 is provided and
that the plurality of assembled batteries 23 are housed in the
module case 31 in a state wherein they are interconnected
electrically in series. The respective terminals (aggregate
positive and negative tabs 5 and 7) of each of the assembled
batteries 23 housed in the module case 31 are connected to the
terminals of the adjacent assembled batteries 23 through the
busbars 32. Then, the terminals of the assembled batteries 23
disposed on the outermost sides among the plurality of assembled
batteries 23 are connected to the external terminals 34 provided on
the outside surface of the module case 31.
[0074] In the battery module 30 thus constituted, the assembled
batteries 23 having high energy efficiency per unit volume are
housed in the module case 31 and are integrated in one body.
Therefore, the battery module 30 is highly powered, compact and has
excellent handling. Particularly, for the single cells 20
constituting the respective assembled batteries 23 housed in the
module case 31, the laminate cell 1 or 11, in which the temperature
increase in the positive and negative tabs 5 and 7 can be
controlled, and the laminate cell 13, in which insulating tape is
adhered to the junction portions of the positive and negative tabs
5 and 7, are used. Therefore, high reliability, even when a large
current is carried, is ensured for each of the single cells 20. In
this connection, the battery module 30 is suitable for, for
example, use in an electric vehicle regarding high power.
Sixth Embodiment
[0075] Next, an example of an electric vehicle having the battery
module 30 as described above mounted thereon will be described with
reference to FIG. 9. FIG. 9 schematically illustrates the drive
system of the electric vehicle 40 of this embodiment.
[0076] As illustrated in FIG. 9, in the electric vehicle 40 of this
embodiment, the above-described battery module 30 is used as a
power source for the driving motor 42 driving the drive wheels 41.
This battery module 30 is designed to be charged by the battery
charger 43, and supplies predetermined power to the driving motor
42 through the power converter 44 according to needs. In addition,
the battery module 30 is charged by regenerated power generated by
a regenerative braking of the driving motor 42.
[0077] The charge/discharge of the battery module 30 is controlled
by the vehicle control unit 45. Specifically, the vehicle control
unit 45 calculates a power quantity required for the driving motor
42 based on outputs from various sensors such as the accelerator
sensor 46, the brake sensor 47 and the speed sensor 48. Based on
the calculated power quantity, the vehicle control unit 45 controls
a power supply from the battery module 30 to the driving motor 42.
In addition, the vehicle control unit 45 monitors the charge state
of the battery module 30, and controls a charge from the battery
charger 43 such that the charge state of the battery module 30 is
maintained in an appropriate state.
[0078] In the electric vehicle 40 thus constituted, the battery
module 30, which is highly powered, compact and has excellent
handling, is used as the power source of the driving motor 42
driving the drive wheels 41. Particularly, as for each of the
single cells constituting the assembled batteries in this module,
the laminate cell, in which the temperature increase in the
positive and negative tabs can be controlled, and the laminate
cell, in which insulating tape is adhered to the junction portions
of the positive and negative tabs, are used. Thus, high
reliability, even when a large current is carried is ensured for
each of the single cells, and high running performance can be
realized.
[0079] Note that, though the above has been described by taking, as
an example, the electric vehicle 40 which runs driven by the
driving motor 42, it is also possible to apply the present
invention to a so-called hybrid car which runs via a combination of
an engine and the driving motor. Specifically, also in the case
where the present invention is applied to the hybrid car, the
battery module 30 as described above can be used as the power
source of the driving motor.
[0080] The entire content of Japanese Patent Application No.
P2002-245539 with a filing date of Aug. 26, 2002 is herein
incorporated by reference.
[0081] Although the invention has been described above by reference
to certain embodiments of the invention, the invention is not
limited to the embodiments described above will occur to these
skilled in the art, in light of the teachings. The scope of the
invention is defined with reference to the following claims.
* * * * *