U.S. patent application number 16/982034 was filed with the patent office on 2021-01-21 for solid-state battery module.
The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Masahiro OHTA, Takuya TANIUCHI.
Application Number | 20210020880 16/982034 |
Document ID | / |
Family ID | 1000005192874 |
Filed Date | 2021-01-21 |
United States Patent
Application |
20210020880 |
Kind Code |
A1 |
TANIUCHI; Takuya ; et
al. |
January 21, 2021 |
SOLID-STATE BATTERY MODULE
Abstract
Provided is a battery module having a high energy density and
exhibiting suppressed electrode displacement or peeling during
vibration. In the present invention, a residual space in a battery
cell, which is necessary for the lithium ion secondary batteries
employing the liquid electrolyte is eliminated, and additionally a
module component is disposed in a portion that would provide the
residual space.
Inventors: |
TANIUCHI; Takuya; (Saitama,
JP) ; OHTA; Masahiro; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
1000005192874 |
Appl. No.: |
16/982034 |
Filed: |
February 27, 2019 |
PCT Filed: |
February 27, 2019 |
PCT NO: |
PCT/JP2019/007695 |
371 Date: |
September 17, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/486 20130101;
H01M 50/209 20210101; H01M 50/20 20210101; H01M 50/531 20210101;
H01M 10/482 20130101 |
International
Class: |
H01M 2/10 20060101
H01M002/10; H01M 2/26 20060101 H01M002/26; H01M 10/48 20060101
H01M010/48 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2018 |
JP |
2018-061753 |
Claims
1. A solid-state battery module comprising a plurality of
solid-state batteries and a module component, wherein the plurality
of solid-state batteries are arranged so as to be substantially
parallel to a predetermined direction, each of the plurality of
solid-state batteries comprises a solid-state battery cell, and a
battery case for accommodating the solid-state battery cell,
wherein the solid-state battery cell comprises a positive
electrode, a negative electrode, a solid electrolyte present
between the positive electrode and the negative electrode, a
positive electrode tab connected to the positive electrode, and a
negative electrode tab connected to the negative electrode, wherein
an outer dimension of the battery case is substantially identical
to an outer dimension of the solid-state battery cell, and wherein
the battery case comprises a recess, and the module component is
disposed in the recess.
2. The solid-state battery module according to claim 1, wherein the
module component is at least one selected from the group consisting
of a bus bar, a thermistor, a harness, a voltage detection line, a
battery case fixing member, and a cell voltage and temperature
monitoring unit.
3. The solid-state battery module according to claim 1, wherein the
battery case comprises at least one convex portion, and the
positive electrode tab and the negative electrode tab are stored in
the convex portion.
4. The solid-state battery module according to claim 1, wherein the
battery case comprises at least two convex portions, and the
positive electrode tab and the negative electrode tab are each
stored in a different convex portion.
5. The solid-state battery module according to claim 4, wherein the
convex portion for storing the positive electrode tab and the
convex portion for storing the negative electrode tab are provided
on same face in the battery case.
6. The solid-state battery module according to claim 4, wherein the
convex portion for storing the positive electrode tab and the
convex portion for storing the negative electrode tab are provided
on different faces in the battery case.
7. The solid-state battery module according to claim 1, wherein the
battery case is made of metal, a face constituting the battery case
which is substantially parallel to the predetermined direction
comprises a pressing portion for applying a surface pressure to the
solid-state battery cell, and a gap is defined between two adjacent
solid-state batteries of the plurality of solid-state batteries by
the pressing portion.
8. The solid-state battery module according to claim 7, wherein the
pressing portion is provided only on one face of the battery
case.
9. The solid-state battery module according to claim 7, wherein the
pressing portion is provided on a set of opposing faces of the
battery case.
10. The solid-state battery module according to claim 6, wherein at
least one selected from the group consisting of air, water, a heat
transfer material, a heater and the like, and an electrically
insulating material or an electrically conductive material, a
cushioning material and a battery case fixing member and the like
is present in the gap.
11. The solid-state battery module according to claim 6, wherein a
heat sink is disposed in the pressing portion.
12. The solid-state battery module according to claim 11, wherein
the heat sink is a fin or an uneven structure.
13. The solid-state battery module according to claim 1, wherein
the solid-state battery comprises an expansion material between the
solid-state battery cell and the battery case, and the expansion
material expands in volume by water absorption or a chemical
reaction, or changes in volume by heat.
14. An apparatus comprising the solid-state battery module
according to claim 1.
Description
[0001] This application is based on and claims the benefit of
priority from Japanese Patent Application No. 2018-061753, filed on
28 Mar. 2018, the content of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a solid-state battery
module.
Furthermore, the present invention relates to a battery module
having a high energy density, ensuring sufficient surface pressure,
and exhibiting suppressed electrode displacement during
vibration.
BACKGROUND ART
[0003] Conventionally, lithium ion secondary batteries are widely
used as secondary batteries with high energy density.
Such a lithium ion secondary battery includes a structure in which
a separator is disposed between a positive electrode and a negative
electrode, and the space between the positive electrode and the
negative electrode is filled with a liquid electrolyte (electrolyte
solution).
[0004] Since the electrolyte solution of the secondary lithium-ion
battery is usually a flammable organic solvent, the safety to heat,
in particular, becomes a problem in some cases. Therefore, a
solid-state battery employing an inorganic solid electrolyte
instead of the organic liquid electrolyte has been proposed (see
Patent Document 1)
Solid-state batteries employing the solid electrolyte eliminates
the problem arising from heat, and additionally allows for an
increase in capacity and/or voltage by stacking, and further can
meet the demand for compactness, as compared with the batteries
employing the electrolyte solution.
[0005] Examples of the shape of such a secondary battery include a
cylindrical shape, a rectangular shape, and the like. Then, a
secondary battery module is constructed when the secondary battery
is used for devices requiring a large current and a large voltage,
e.g. motor drives for hybrid electric vehicles, and the like.
[0006] The secondary battery module includes a plurality of
secondary batteries connected in series, and includes a battery
case which includes a space for accommodating the plurality of
secondary batteries and electrode connection portions, and a module
component coupled to the battery case (see Patent Document 2).
[0007] A more specific secondary battery module has, for example, a
configuration in which a battery cell 202 and a separator 216 are
alternately stacked and the stack is fixed using end plates 217 and
binding bars 214 provided at both ends of the stack, as shown in
FIG. 1(a), which is a cross-sectional view of the battery module
200 taken along the stacking direction of the battery, and in FIG.
1(b), which is a sectional view of the battery module 200 taken
along the line A-A'.
[0008] However, as shown in FIG. 1(b), the battery 201 constituting
the conventional secondary battery module includes a space between
a battery case 203 and a battery cell 202 for the purpose of
storing a gas which may be generated in the case of a liquid
electrolyte or of introducing the electrolyte solution.
This residual space reduces the energy density of the cell.
[0009] Furthermore, in the conventional battery module, the module
components (in FIG. 1(b), terminals 205, bus bars 206, voltage
detection lines 207, a thermistor 208, binding bars 214, a lower
plate 215, a thermally conductive material 218, and cooling water
219) are arranged outside the battery case 203 with the module
components being superposed on the electrode connection
portion.
Therefore, the volume of the entire battery module (i.e., the
region indicated by a broken line) is large, leading to a reduction
of the energy density of the module. Further, in some cases,
electrode displacement or the like occurs due to vibration or the
like. [0010] Patent Document 1: Japanese Unexamined Patent
Application, Publication No. 2000-106154 [0011] Patent Document 2:
Japanese Unexamined Patent Application, Publication No.
2006-278327
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0012] The present invention has been made in view of the above
background art, and an object thereof is to provide a battery
module having a high energy density and exhibiting suppressed
electrode displacement during vibration.
Means for Solving the Problems
[0013] The present inventors have focused on the facts that in the
solid-state battery including a solid electrolyte, the amount of a
gas generated during charging and discharging is extremely small,
unlike the lithium ion secondary battery employing a liquid
electrolyte, and also that swelling of the battery due to the
introduction of the electrolyte is unlikely. Then, the present
inventors have found that a solid-state battery module having a
high energy density and exhibiting suppressed displacement or
peeling or the like of the battery cell during vibration can be
achieved by eliminating the residual space in the battery cell,
which is necessary for the lithium ion secondary batteries
employing a liquid electrolyte, and additionally arranging the
module components in the portion that would provide the residual
space, to thereby complete the present invention.
[0014] Specifically, a first aspect of the present invention
relates to a solid-state battery module including a plurality of
solid-state batteries and a module component, in which the
plurality of solid-state batteries are arranged so as to be
substantially parallel to a predetermined direction, each of the
plurality of solid-state batteries includes a solid-state battery
cell, and a battery case for accommodating the solid-state battery
cell, in which the solid-state battery cell includes a positive
electrode, a negative electrode, a solid electrolyte present
between the positive electrode and the negative electrode, a
positive electrode tab connected to the positive electrode, and a
negative electrode tab connected to the negative electrode, in
which the outer dimension of the battery case is substantially
identical to the outer dimension of the solid-state battery cell,
and in which the battery case has a recess, and the module
component is disposed in the recess.
[0015] The module component may be at least one selected from the
group consisting of a bus bar, a thermistor, a harness, a voltage
detection line, a battery case fixing member, a cell voltage and
temperature monitoring unit and the like.
[0016] The battery case may have at least one convex portion, and
the positive electrode tab and the negative electrode tab may be
stored in the convex portion.
[0017] The battery case may have at least two convex portions, and
the positive electrode tab and the negative electrode tab may be
each stored in a different convex portion.
[0018] The convex portion for storing the positive electrode tab
and the convex portion for storing the negative electrode tab may
be provided on the same face in the battery case.
[0019] The convex portion for storing the positive electrode tab
and the convex portion for storing the negative electrode tab may
be provided on different faces in the battery case.
[0020] The battery case may be made of metal, the face constituting
the battery case which is substantially parallel to the
predetermined direction may have a pressing portion for applying a
surface pressure to the solid-state battery cell, and a gap may be
defined between two adjacent solid-state batteries of the plurality
of solid-state batteries by the pressing portion.
[0021] The pressing portion may be provided only on one face of the
battery case.
[0022] The pressing portion may be provided on a set of opposing
faces of the battery case.
[0023] At least one selected from the group consisting of air,
water, a heat transfer material, a heater and the like for
controlling the cell temperature, and an electrically insulating
material or an electrically conductive material for making the
module function, a cushioning material and a battery case fixing
member and the like may be present in the gap.
[0024] A heat sink may be disposed in the pressing portion.
[0025] The heat sink may be a fin or an uneven structure.
[0026] The solid-state battery may include an expansion material
between the solid-state battery cell and the battery case, and the
expansion material may expand in volume by water absorption or a
chemical reaction, or change in volume by heat.
[0027] Another aspect of the present invention relates to an
apparatus including the solid-state battery module described
above.
Effects of the Invention
[0028] The solid-state battery module according to the aspect of
the present invention has a high energy density, and exhibits
suppressed electrode displacement during vibration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a side view and a sectional view taken along the
line A-A' of a conventional secondary battery module;
[0030] FIG. 2 is a side view and a sectional view taken along the
line A-A' of a solid-state cell module according to an embodiment
of the present invention;
[0031] FIG. 3 is a cross-sectional view of an embodiment of a
solid-state battery constituting the solid-state battery
module;
[0032] FIG. 4 is a cross-sectional view of an embodiment of a
solid-state battery constituting the solid-state battery
module;
[0033] FIG. 5 is a cross-sectional view of an embodiment of a
solid-state battery constituting the solid-state battery module;
and
[0034] FIG. 6 is a simplified side view of an embodiment of the
solid-state battery constituting a solid-state battery module.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
[0035] Hereinafter, embodiments of the present invention will be
described with reference to the accompanying drawings. However, the
embodiments described below merely illustrate the present
invention, and the present invention is not limited to the
following.
[0036] <Solid-State Battery Module>
The solid-state battery module according to an embodiment of the
present invention is characterized in that the solid-state battery
module includes a plurality of solid-state batteries and a module
component, in which the plurality of solid-state batteries are
arranged so as to be substantially parallel to a predetermined
direction, each of the plurality of the solid-state batteries
includes a solid-state battery cell, and a battery case for
accommodating the solid-state battery cell, in which the
solid-state battery cell includes a positive electrode, a negative
electrode, a solid electrolyte present between the positive
electrode and the negative electrode, a positive electrode tab
connected to the positive electrode, and a negative electrode tab
connected to the negative electrode, in which the inner dimension
of the battery case is substantially identical to the outer
dimension of the solid-state battery cell, and in which the battery
case has a recess, and the module component is disposed in the
recess. Hereinafter, each component will be described with
reference to the drawings.
[0037] [Battery Module of Conventional Structure]
First, a description will be given of a battery module of a
conventional structure. FIGS. 1(a) and 1(b) are each a diagram
showing a battery module of a conventional structure. FIG. 1(a) is
a cross-sectional view of a battery module 200 taken along the
stacking direction of the battery 201, and FIG. 1(b) is a
cross-sectional view of the battery module 200 taken along the line
A-A'.
[0038] In the conventional battery module 200, a plurality of
batteries 201 are arranged so as to be substantially parallel to a
predetermined direction, as shown in FIG. 1(a).
A separator 216 is disposed between the adjacent batteries 201 so
that the separator 216 provides electrical isolation and applies an
even pressure to the batteries 201 constituting the module. End
plates 217 and binding bars 214 are disposed at both ends of the
stack of the batteries 201 and the separators 216. The end plates
217 apply a surface pressure to the stack of the plurality of
batteries 201 and the plurality of separators 216 to maintain their
alignment, and the binding bars 214 enhance their binding.
[0039] As shown in FIG. 1(a), the upper face of the conventional
battery module 200 is covered with a top cover 213 corresponding to
a lid of the module, and the electrical insulation is maintained by
the top cover 213.
In addition, the stack of the batteries 201 and the separators 216
is fixed to a lower plate 215 by the binding bar 214, to maintain
the shape of the stack. Further, a thermally conductive material
218 such as a silicon compound and cooling water 219 are disposed
on the bottom face of the battery module 200 (i.e., the surface on
which the lower plate 215 resides) for the purpose of conducting
heat from the stack of the batteries 201 and cooling the stack.
[0040] Further, in the conventional battery module 200, the battery
201 includes a battery cell 202 and a battery case 203 for
accommodating the battery cell 202, as shown in FIG. 1(b), which is
a cross-sectional view taken along the line A-A' in FIG. 1(a).
[0041] Furthermore, the conventional battery cell 202 has a
positive electrode (not shown), a negative electrode (not shown),
an electrolyte (not shown) present between the positive electrode
and the negative electrode, a positive electrode tab 204 connected
to the positive electrode, and a negative electrode tab 209
connected to the negative electrode. Then, a space is provided
between the battery case 203 and the battery cell 202 for the
purpose of storing a gas generated in the case of a liquid
electrolyte and/or for the purpose of introducing the electrolyte
solution.
In other words, in the conventional battery 201, there is a
difference in outer dimension between the battery cell 202 and the
battery case 203, and the battery case 203 has a residual space in
which no battery cell 202 resides. This residual space reduces the
energy density of the battery cell.
[0042] In addition, in the conventional battery module 200, a
terminal 205, a bus bar 206, a voltage detection line 207, and a
thermistor 208, which each correspond to the module component 210,
are disposed outside the battery case 203, with the module
components being superposed on the positive electrode tab 204 and
the negative electrode tab 209, as shown in FIGS. 1(a) and
1(b).
Then, the battery module 200 is covered by the top cover 213 so as
to store the superposed module components 210. Therefore, in the
conventional battery module 200, the volume of the entire battery
module 200 (i.e., the region indicated by the broken line) is
larger than the volume of the battery case 203 which provides the
outer shape of the battery 201, resulting in a low energy density
of the module. Further, in some cases, electrode displacement or
the like occurs in the conventional battery module 200 due to
vibration or the like.
[0043] [Solid-State Battery Module according to Embodiment of the
Present Invention]
In contrast, the solid-state battery module according to the
embodiment of the present invention is characterized by including
an extremely small residual space in the solid-state battery
constituting the module and arranging the module component in a
portion that would be the residual space.
[0044] Specifically, the solid-state battery module according to
the embodiment of the present invention includes a plurality of
solid-state batteries and a module component, in which the
plurality of solid-state batteries are arranged so as to be
substantially parallel to a predetermined direction, each of the
plurality of solid-state batteries includes a solid-state battery
cell, and a battery case for accommodating the solid-state battery
cell, in which the solid-state battery cell includes a positive
electrode, a negative electrode, a solid electrolyte present
between the positive electrode and the negative electrode, a
positive electrode tab connected to the positive electrode, and a
negative electrode tab connected to the negative electrode, in
which the inner dimension of the battery case is substantially
identical to the outer dimension of the solid-state battery cell,
and in which the battery case has a recess, and the module
component is disposed in the recess.
[0045] FIGS. 2(a) and 2(b) are each a diagram showing an embodiment
of the solid-state battery module of the present invention.
FIG. 2(a) is a cross-sectional view of the battery module 100 taken
along the stacking direction of the plurality of batteries 101
(i.e., a direction perpendicular to the predetermined direction),
and FIG. 2(b) is a cross-sectional view of the battery module 100
taken along the line A-A'. The battery module 100 according to the
embodiment of the present invention shown in FIGS. 2(a) and 2(b)
includes a plurality of solid-state batteries shown in FIG.
3(a).
[0046] In the battery module 100, which is an embodiment of the
solid-state battery module of the present invention, the plurality
of batteries 101 are arranged so as to be substantially parallel to
the predetermined direction, as shown in FIG. 2(a).
In the case of the battery module 100, which is an embodiment of
the present invention, no separator is disposed between the
adjacent batteries 101, but separators may be disposed as required
in the present invention.
[0047] In the battery module 100, which is an embodiment of the
present invention, only the binding bars 114 are disposed at both
ends of the stack of the batteries 101 to enhance binding of the
stack.
Note that in the case of the battery module 100, which is an
embodiment of the present invention, an end plate is not disposed
at either end of the plurality of batteries 101. However, in the
case where the application of a surface pressure to the stack of
the batteries 101 is necessary, an end plate may be disposed as
required.
[0048] As shown in FIG. 2(a), the upper face of the battery module
100, which is an embodiment of the present invention, is covered
with a top cover 113 corresponding to the lid of the module, and
the electrical insulation is maintained by the top cover 113.
The stack of the batteries 101 is also secured to the lower plate
115 by a binding bar 214 to maintain its shape. In the case of the
battery module 100, which is an embodiment of the present
invention, a thermally conductive material such as a silicon
compound or cooling water is not disposed on the bottom face of the
battery module 100 (i.e., the surface on which the lower plate 115
resides). However, in the case where dissipation of heat from the
stack of the batteries 101 and cooling thereof are necessary, the
heat conductive material or cooling water may be disposed as
required.
[0049] (Arrangement Direction of Solid-State Battery (Predetermined
Direction))
In the solid-state battery module according to the embodiment of
the present invention, the plurality of solid-state batteries are
arranged so as to be substantially parallel to the predetermined
direction. The arrangement direction of the solid-state batteries
is not particularly limited in the embodiment of the present
invention.
[0050] For example, in the solid-state battery module according to
the embodiment of the present invention shown in FIG. 2, the
arrangement direction of the solid-state batteries (defined herein
as a "predetermined direction") aligns with a direction
substantially perpendicular to the top cover 113 and the lower
plate 115.
However, in the present invention, the arrangement direction is not
limited to this direction. The solid-state batteries may be stacked
so as to be substantially parallel to the top cover 113 and the
lower plate 115. When the solid-state batteries are arranged
substantially parallel to the top cover 113 and the lower plate
115, a module having a large footprint can be achieved, and thus an
improvement of the energy density of the module can be achieved
along with an improvement of an electrode filling rate.
[0051] Next, the features of the solid-state battery module
according to the embodiment of the present invention will be
described with reference to FIG. 2(b).
[0052] In the battery module 100, which is an embodiment of the
present invention, the battery 101 includes a battery cell 102 and
a battery case 103 for accommodating the battery cell 102, as shown
in FIG. 2(b), which is a cross-sectional view taken along the line
A-A' in FIG. 2(a).
[0053] Then, the battery cell 102, which is an embodiment of the
present invention, has, like the conventional battery cell, a
positive electrode (not shown), a negative electrode (not shown), a
solid electrolyte (not shown) present between the positive
electrode and the negative electrode, a positive electrode tab 104
connected to the positive electrode, and a negative electrode tab
109 connected to the negative electrode.
[0054] Here, the present invention is characterized in that a space
corresponding to the residual space in the battery is extremely
small.
In other words, in the conventional battery, there is a difference
in outer dimension between the battery cell and the battery case,
and the battery case has a residual space in which no battery cell
resides. However, in the battery constituting the battery module
according to the embodiment of the present invention, the outer
dimension of the battery case is substantially identical to the
outer dimension of the solid-state battery cell, and such a
residual space as in the conventional battery is not formed
purposefully. More specifically, the battery case covers the
battery cell along the outer shape of the battery cell, and the
portion corresponding to the conventional residual space is present
as a recess. This makes it possible to improve the energy density
in each battery, and to improve the degree of freedom in design of
the battery shape.
[0055] Referring to the battery module 100, which is an embodiment
of the present invention, the outer shape of the battery case 103
conforms to the outer shape of the battery cell 102, and there is
no residual space between the positive electrode tab 104 and the
negative electrode tab 109 inside the battery case 103, as shown in
FIG. 2(b).
A recess is formed between the positive electrode tab 104 and the
negative electrode tab 109. That is, on the upper face of the
battery cell 102, there is a recess in the region corresponding to
the residual space in the conventional battery.
[0056] The present invention is further characterized by arranging
the module component(s) in the portion that would provide a
residual space in the conventional battery. More specifically, in
the conventional battery module, the module components such as the
terminal, the bus bar, the voltage detection line, and the
thermistor are arranged outside of the battery case having the
residual space, with the module components being superposed on the
positive electrode tab and the negative electrode tab. However, in
the battery module according to the embodiment of the present
invention, the module components are arranged in the recess in the
battery constituting the module, the recess being formed in the
region corresponding to the residual space in the conventional
battery.
This makes it possible to reduce the volume of the entire battery
module, and consequently to improve the energy density of the
battery module. Further, electrode displacement or the like due to
vibration or the like can be suppressed.
[0057] Referring to the battery module 100, which is an embodiment
of the present invention, the terminals 105 constituting the module
component 110 are arranged in the recess of the battery case 103,
with the terminals 105 being electrically connected to the positive
electrode tab 104 and the negative electrode tab 109, as shown in
FIG. 2(b).
Further, other module components 110, i.e., the bus bar 106, the
voltage detection line 107, and the thermistor 108 are arranged in
the recess of the battery case 103, so as to line up with the
terminals 105.
[0058] <Solid-State Battery>
The solid-state battery includes the solid-state battery cell and
the battery case for accommodating the solid-state battery cell. As
shown in FIG. 2(b), which is a cross-sectional view taken along the
line A-A' in FIG. 2(a), the battery 101 according to the embodiment
of the present invention includes the battery cell 102 and the
battery case 103 for accommodating the battery cell 102.
[0059] [Solid-State Battery Cell]
The solid-state battery cell, like the conventional battery cell,
includes the positive electrode, the negative electrode, the solid
electrolyte present between the positive electrode and the negative
electrode, the positive electrode tab connected to the positive
electrode, and the negative electrode tab connected to the negative
electrode. The solid-state battery cell in the embodiment of the
present invention can function whether it is a stack of electrodes
or a laminated cell.
[0060] The battery cell 102 shown in FIG. 2(b), which is an
embodiment of the present invention, has a positive electrode layer
(not shown), a negative electrode layer (not shown), a solid
electrolyte layer (not shown) present between the positive and
negative electrode layers, a positive electrode tab 104 connected
to the positive electrode layer, and a negative electrode tab 109
connected to the negative electrode layer.
[0061] (Positive Electrode and Negative Electrode)
The positive and negative electrodes constituting the solid-state
battery of the solid-state battery module according to the
embodiment of the present invention are not particularly limited,
as long as they are usable as a positive electrode or a negative
electrode of the solid-state battery. The positive electrode and
the negative electrode each include an active material and a solid
electrolyte, and may optionally include a conductivity aid, a
binder, and the like.
[0062] The positive and negative electrodes constituting the
solid-state battery of the solid-state battery module according to
the embodiment of the present invention may be prepared by
selecting two types of materials from the materials capable of
constituting an electrode, comparing the charge and discharge
potentials of the two types of compounds, and assigning one
exhibiting a higher potential to the positive electrode, and the
other exhibiting a lower potential to the negative electrode, and
this process allows any battery to be configured.
[0063] (Solid Electrolyte)
The solid electrolyte constituting the solid-state battery of the
solid-state battery module according to the embodiment of the
present invention includes a binder and the like, as needed. In the
embodiment of the present invention, the material of the solid
electrolyte is not particularly limited as long as it is usable as
a solid electrolyte of a solid-state battery. For example, the
solid electrolyte is exemplified by an oxide-based solid
electrolyte and a sulfide-based solid electrolyte. Note that the
composition ratio of each substance contained in the solid
electrolyte is not particularly limited as long as the battery can
be appropriately operated.
[0064] Further, the thickness, shape and the like of the solid
electrolyte are not particularly limited, as long as the solid
electrolyte can be appropriately present between the positive
electrode and the negative electrode and ion conduction between the
positive electrode and the negative electrode is possible.
Further, there is no particular limitation on the manufacturing
method for the solid electrolyte.
[0065] (Positive Electrode Tab/Negative Electrode Tab)
The positive and negative electrode tabs are respectively connected
to the current collecting foils of the positive electrode and the
negative electrode, and serve as a current collector for the
battery. With regard to the positive and negative electrode tabs
constituting the solid-state battery of the solid-state battery
module according to the embodiment of the present invention, the
material, structure, and the like thereof are not particularly
limited, as long as the tabs are a current collector used in the
solid-state battery. In the embodiment of the present invention,
the material for the positive and negative electrode tabs is
exemplified by a metal foil having a thickness of about 10 to 500
.mu.m, or the like.
[0066] (Tab Arrangement)
In the solid-state battery constituting the solid-state battery
module according to the embodiment of the present invention, the
positive electrode tab and the negative electrode tab are
respectively connected to the current collecting foil of the
positive electrode layer and the negative electrode layer. Thus, in
the battery cell, the positive and negative electrode tabs are
provided so as to extend from the end faces of the stack of the
positive electrode layer, the solid electrolyte layer, and the
negative electrode layer.
[0067] Here, the arrangement of the tabs will be described with
reference to the drawings.
FIG. 2(b) is a cross-sectional view of the battery module 100
according to the embodiment of the solid-state battery module of
the present invention taken along the line A-A', and FIGS. 3(a) and
3(b) are each a cross-sectional view of a solid-state battery
according to an embodiment constituting the solid-state battery
module of the present invention. FIGS. 3(a) and 3(b) show
cross-sections of the positive electrode tab 104 portion and the
negative electrode tab 109 portion, respectively, taken along a
direction parallel to the stacking direction (indicated by the left
right arrow) of the stack of the positive electrode layer, the
solid electrolyte layer, and the negative electrode layer, which
constitute the battery cell 102, and FIG. 2(b) shows a
cross-section taken along a direction perpendicular to the stacking
direction.
[0068] As shown in FIGS. 3(a) and 3(b), the positive electrode tab
104 and the negative electrode tab 109 are respectively provided in
connection with the current collecting foils of the positive
electrode and the negative electrode so as to extend from the end
faces of the stack of the positive electrode layer, the solid
electrolyte layer, and the negative electrode layer, which
constitute the battery cell 102.
In the embodiment shown in FIG. 2(b), the positive electrode tab
104 and the negative electrode tab 109 each extend from a different
site at the same end face of the stack of the positive electrode
layer, the solid electrolyte layer, and the negative electrode
layer of the battery cell 102. Then, in the embodiment shown in
FIG. 2(b), the battery case 103 is provided with two convex
portions, one being for storing the positive electrode tab 104 and
the other being for storing the negative electrode tab 109, and the
positive electrode tab 104 and the negative electrode tab 109 are
each stored in the convex portion therefor.
[0069] In the present invention, the positive electrode tabs 104
and the negative electrode tabs 109 may be arranged so as to extend
from the same end face of the stack of the positive electrode
layer, the solid electrolyte layer, and the negative electrode
layer, which constitute the battery cell, as shown in FIGS. 2(b),
3(a) to 3(b), and 4, or may be separately arranged so that the
positive electrode tabs 104 and the negative electrode tabs 109
each extend from a different end face, as shown in FIGS. 5(a) to
5(c).
[0070] [Battery Case]
(Outer Dimension)
[0071] The outer dimension of the battery case of the solid-state
battery constituting the solid-state battery module according to
the embodiment of the present invention is substantially identical
to the outer dimension of the solid-state battery cells. This is
because, unlike a lithium ion secondary battery into which a liquid
electrolyte is introduced, the solid-state battery does not require
a space for storing a gas or a space for introducing an electrolyte
solution. In other words, in the case of the solid-state battery,
after inserting the battery cell into the battery case, the amount
of the gas to be generated in the battery cell is negligibly small,
and therefore the residual space is not required.
[0072] Thus, the battery case of the solid-state battery
constituting the solid-state battery module according to the
embodiment of the present invention has an extremely small space
corresponding to the residual space, and covers the battery cell
conforming to the outer shape of the battery cell. In the
embodiment of the present invention, this makes it possible to
reduce the volume of the solid-state battery, and consequently to
improve the energy density of each battery and the degree of
freedom in design of the battery shape.
[0073] In FIG. 2(b), which is a cross-sectional view of the
solid-state battery module according to an embodiment of the
present invention, the battery cell 102 is accommodated in the
battery case 103, the battery case 103 covers the battery cell 102
conforming to the outer shape of the battery cell 102, and the
outer dimension of the battery case 103 is substantially identical
to the outer dimension of the battery cell 102.
[0074] (Recess)
As described above, since the battery case of the solid-state
battery constituting the solid-state battery module according to
the embodiment of the present invention covers the battery cell
conforming to the outer shape of the battery cell, and its outer
dimension is substantially identical to the outer dimension of the
solid-state battery cell, the portion corresponding to the residual
space in the conventional battery portion will be present as a
recess in the battery case.
[0075] In other words, since the recess in the embodiment of the
present invention is a space which corresponds to the residual
space in the conventional battery, the position where the recess is
formed is not particularly limited in the battery case.
In any face of the battery case, the recess may be formed in a
central portion of the face or in a peripheral portion thereof.
Further, not only one recess, but also more than one recess may be
provided in the battery case.
[0076] In the solid-state battery module according to the
embodiment of the present invention, the module component is
arranged in the recess of the battery case.
This makes it possible to reduce the volume of the entire battery
module, and consequently to improve the energy density of the
battery module. Furthermore, since there is no residual space in
the battery case, the displacement or peeling of the battery cell
due to vibration or the like can also be suppressed.
[0077] In FIG. 2(b), which is a cross-sectional view of the
solid-state battery module according to the embodiment of the
present invention, the thermistor 108, which is a module component,
is disposed in the recess formed in the battery case 103.
[0078] (Materials)
The material of the battery case is not particularly limited, but
is preferably a metal. When the material is a metal, the heat
dissipation may be improved, and the sealability of the battery
case may be improved because of an improvement of the strength of
the case itself as well as the weldability thereof.
[0079] (Pressing Portion)
In the case of a lithium ion secondary battery including a liquid
electrolyte, inserting a battery cell into a battery case, followed
by introducing an electrolyte solution causes the battery cell to
swell with the electrolyte solution. Further, by performing the
initial charging and discharging, followed by aging, the battery
cell expands in volume. As a result, the battery case and the
battery cell are in close contact, and surface pressure is
generated therebetween.
[0080] However, with regard to the solid-state battery including a
solid electrolyte, since the volume expansion of the battery cell
is small after inserting the battery cell into the battery case, a
sufficient surface pressure to the battery according to the above
method is not generated.
Thus, the battery case of the solid-state battery constituting the
solid-state battery module according to the embodiment of the
present invention preferably has a pressing portion for applying a
surface pressure to the solid-state battery cell.
[0081] The pressing portion exerts the action of applying a surface
pressure to the solid-state battery cell by force of a spring.
Therefore, the pressing portion is provided in a face substantially
perpendicular to the stacking direction of the stack of the
positive electrode layer, the solid electrolyte layer, and the
negative electrode layer in the solid-state battery cell (i.e., a
face substantially parallel to the positive electrode layer, the
solid electrolyte layer, and the negative electrode layer). This
allows for an application of surface pressure in the stacking
direction of the stack of the positive electrode layer, the solid
electrolyte layer, and the negative electrode layer, and for the
application of an initial load to a single battery cell, thereby
improving the input-output characteristics and the vibration
resistance.
[0082] Further, since the pressing portion is present on the face
substantially parallel to the arrangement direction of the
solid-state battery in the solid-state battery module of the
present invention (the predetermined direction), surface pressure
is applied to the entire module, which makes it possible to omit
the separator between the adjacent batteries and to omit the end
plates at both ends of the module.
As a result, the volume of the entire module can be reduced,
leading to an improvement of the energy density of the battery
module.
[0083] The pressing portion in the embodiment of the present
invention may be provided only on one face of the battery case, or
may be provided on a set of opposing faces.
When the pressing portion is provided only on one face of the
battery case, surface pressure will be applied in the stacking
direction only from one side of the stack of the positive electrode
layer, the solid electrolyte layer, and the negative electrode
layer in the battery cell. In the case where the pressing portion
is provided on a set of opposing faces, the stack of the positive
electrode layer, the solid electrolyte layer, and the negative
electrode layer in the battery cell can be sandwiched, and surface
pressure can be applied in the stacking direction from both sides.
In the present invention, the pressing portion is preferably
provided on the set of opposing faces.
[0084] FIGS. 3 and 4 are cross-sectional views of an embodiment of
the solid-state battery constituting the solid-state battery module
of the present invention.
In the battery cell 102 in the battery 101 of FIGS. 3 and 4, the
pressing portion 112 is provided on the face substantially
perpendicular to the stacking direction of the stack of the
positive electrode layer, the solid electrolyte layer, and the
negative electrode layer (shown by the left right arrow). In the
battery 101 of FIGS. 3(a) and 4, the pressing portions 112 are
provided on a set of opposing faces. In FIG. 3(b), the pressing
portion 112 is provided only on one face of the battery case
103.
[0085] The structure of the pressing portion is not particularly
limited, as long as it exerts the effect of applying surface
pressure to the solid-state battery cell.
The structure of the pressing portion is exemplified by a stepped
shape, a wavy shape, a shape formed of a curved surface, and the
like.
[0086] In the battery 101 according to the embodiments shown in
FIGS. 3 and 4, the stepped pressing portion 112 is provided.
[0087] Further, the pressing portion may form, in the battery case,
a continuous structure with the portion other than the pressing
portion or a discontinuous structure therewith.
By adopting the discontinuous structure, other forces can be
applied together with the force by the spring.
[0088] In the battery 101 according to the embodiments of FIGS. 3
and 4, the stepped pressing portion 112 is formed discontinuously
with the battery case 103.
The structure in which the pressing portion is slidable inwardly as
in the present embodiment allows for easy application of surface
pressure to the battery cell, for example, when the battery cell is
pressed from both ends during the formation of the solid-state
battery module. Alternatively, when the internal pressure of the
battery cell is increased, a stress can be released, leading to an
improvement in safety.
[0089] (Gap)
In the case where the battery case of the solid-state battery has
the pressing portion, a gap is defined between the adjacent
solid-state batteries in the solid-state battery module of the
present invention. Specifically, in FIG. 2(a), which is a side view
of the solid-state battery module according to the embodiment of
the present invention, the battery module 100 takes a configuration
in which a plurality of the solid-state batteries shown in FIG. 3
are arranged. As shown in FIG. 2(a), in the battery module 100, the
plurality of batteries 101 are arranged so as to be substantially
parallel to the predetermined direction, and the gap 111 is defined
between the adjacent batteries 101 by the pressing portion 112
present in the battery case 103 of the battery 101.
[0090] At least one selected from the group consisting of air,
water, a heat transfer material, a heater and the like for
controlling the cell temperature, an electrically insulating
material or an electrically conductive material for making the
module function, a cushioning material, a battery case fixing
member and the like is preferably present in the gap defined. The
gap defined thus can impart heat dissipation together with
insulating properties.
[0091] {Heat Sink}
Further, it is preferable that the heat sink is disposed in the
pressing portion of the battery case. The heat sink increases the
cooling area and allows for an increase in cooling efficiency,
which also makes it possible to omit cooling means other than the
heat sink, such as cooling water. The configuration of the heat
sink is not particularly limited, and its size is not particularly
limited as long as it can be disposed in the gap. In the case where
the heat sink is disposed in the pressing portion, the heat sink is
preferably a fin. The fin is particularly preferred in terms of
cooling efficiency because it can increase the surface area of the
battery case. Note that the material of the fin is not particularly
limited as long as it has good thermal conductivity. Also, the
shape of the fin is not particularly limited.
[0092] FIG. 4 is an example showing an embodiment of the
solid-state battery including the fin in the pressing portion.
As shown in FIG. 4, in the battery 101, the battery cell 102 is
contained in the battery case 103 having a pressing portion 112,
and a plurality of fins 116 are arranged in the pressing portion
112.
[0093] In the case where the heat sink is provided in the pressing
portion, the heat sink may be an uneven structure formed by
subjecting the battery case surface to embossing or the like.
In the case of the uneven structure formed by subjecting the
battery case surface to embossing or the like, the uneven structure
can impart the cooling effect while suppressing a decrease in
volume energy density of the solid-state battery obtained.
[0094] When the heat sink is the uneven structure, the shape
thereof is not particularly limited, but for example, the heat sink
preferably has a wavy shape.
In the case of the wavy shape, it is possible to generate a spring
pressure of high uniformity in the pressing portion. Examples of
the wavy shape include triangular wave shapes, saw-wave shapes,
rectangular wave shapes, sinus-wave shapes, and the like.
[0095] (Convex Portion)
The battery case of the solid-state battery constituting the
solid-state battery module according to the embodiment of the
present invention has at least one convex portion, and the positive
electrode tab and the negative electrode tab are preferably stored
in the convex portion(s).
[0096] As described above, in the battery case of the solid-state
battery constituting the solid-state battery module according to
the embodiment of the present invention, its outer dimension is
substantially identical to the outer dimension of the solid-state
battery cell, and the portion corresponding to the residual space
in the conventional battery is present as the recess in the battery
case.
Therefore, in the battery cell, the positive electrode tab and the
negative electrode tab extending from the end face of the stack of
the positive electrode layer, the solid electrolyte layer, and the
negative electrode layer will be stored in a portion other than the
recess of the battery case.
[0097] Thus, in the present invention, it is preferable to use a
battery case having a convex portion for storing the positive
electrode tab and the negative electrode tab extending from the end
face of the stack serving as a battery cell, and to store the
positive electrode tab and the negative electrode tab in the convex
portion.
This makes it possible to define the boundary between the convex
portion and the recess formed in the portion corresponding to the
residual space in the conventional battery, and to more densely
pack the module component disposed in the recess. As a result, the
volume of the entire solid-state battery module can be reduced, and
the energy density can be improved.
[0098] Further, it is preferable that the battery case of the
solid-state battery constituting the solid-state battery module
according to the embodiment of the present invention has at least
two convex portions, and that the positive electrode tab and the
negative electrode tab are each stored in a different convex
portion.
[0099] When the battery case of the solid-state battery
constituting the solid-state battery module according to the
embodiment of the present invention has at least two convex
portions, the convex portion for storing the positive electrode
tab, and the convex portion for storing the negative electrode tab
may be provided on the same face in the battery case, or provided
on different faces.
[0100] FIG. 2(b), which is a cross-sectional view of the battery
module 100 according to an embodiment of the solid-state battery
module of the present invention taken along the line A-A', and
FIGS. 3(a), 3(b) and 4, which are each a cross-sectional view of
the solid-state battery according to the embodiment constituting
the solid-state battery module according to the embodiment of the
present invention, show the battery case 103 having two convex
portions, one being for storing the positive electrode tab 104 and
the other being for storing the negative electrode tab 109, and
show an embodiment in which the convex portion for storing the
positive electrode tab 104 and the convex portion for storing the
negative electrode tab 109 are provided on the same face in the
battery case 103.
FIGS. 5(a) to 5(c) show yet another embodiment in which the convex
portion for storing the positive electrode tab 104 and the convex
portion for storing the negative electrode tab 109 are provided on
different faces in the battery case 103.
[0101] [Expansion Material]
As described above, with regard to the solid-state battery
including the solid electrolyte, since the volume expansion of the
battery cell is negligibly small after inserting the battery cell
into the battery case, surface pressure due to the volume expansion
of the battery cell is not generated, unlike the lithium ion
secondary battery including the liquid electrolyte. Thus, the
solid-state battery constituting the solid-state battery module
according to the embodiment of the present invention is preferably
provided with an expansion material between the solid-state battery
cell and the battery case. After inserting the battery cell into
the battery case, the battery case can be brought into close
contact with the battery cell by the expansion material, to thereby
apply surface pressure to the solid-state battery.
[0102] FIG. 6 is an example showing an embodiment of a solid-state
battery including the expansion material between the solid-state
battery cell and the battery case.
As shown in FIG. 6(a), in the solid-state battery according to an
embodiment of the present invention, the expansion material 120 is
preferably disposed between the battery cell 102 and the battery
case 103, and as shown in FIG. 6(b), the expansion material 120 is
preferably expanded, and the battery cell 102 is brought into close
contact with the battery case 103, to thereby apply surface
pressure to the solid-state battery.
[0103] The expansion material is not particularly limited, but an
expansion material which expands in volume by water absorption or a
chemical reaction such as polymerization, or changes in volume by
heat is preferred.
[0104] Assembly of batteries is usually carried out in a dry
environment, but the incorporation of moisture on the order of ppm
is unavoidable.
In the case where the expansion material that expands by water
absorption is used, the expansion material absorbs the incorporated
moisture and expands in volume, to thereby bring the battery case
into close contact with the battery cell, and apply a surface
pressure to the solid-state battery, and additionally the moisture
inside the solid-state battery can be brought close to 0% at the
same time. In particular, when a sulfide-based electrolyte is used,
hydrogen sulfide may be generated due to the presence of moisture,
and may deteriorate the battery cell. Use of the expansion material
which expands by water absorption can suppress the generation of
hydrogen sulfide even when the sulfide-based electrolyte is used,
and as a result, the deterioration of the solid-state battery can
be suppressed. Further, even when the sealing portion of the
solid-state battery is deteriorated and the atmosphere enters, the
expansion material allows for the suppression of the deterioration
of the battery since the expansion material absorbs the moisture in
the atmosphere flowing into the inside of the battery.
[0105] The material which expands in volume by water absorption is
not particularly limited, and examples thereof include zeolites,
silica gels, and the like.
[0106] In addition, in the case where a material which expands in
volume by a chemical reaction such as polymerization is used as an
expansion material, a polymerization initiator may be added in a
polymerization composition, such that timing of the volume
expansion can be adjusted and then the polymerization composition
can be solidified.
Therefore, the volume expansion can be achieved at a timing when
the application of surface pressure is desired.
[0107] The material which expands in volume by a chemical reaction
such as polymerization is not particularly limited, and examples
thereof include urethane foam and the like.
[0108] Further, in the case where those which change in volume by
heat are used as an expansion material, surface pressure can be
ensured by utilizing the difference in thermal expansion
coefficient.
For example, the expansion material may be cooled to or below
ambient temperature to cause contraction in volume of the expansion
material, put into the battery case in its contraction state, and
thereafter expanded by warming the expansion material to ambient
temperature. This allows for close contact of the battery case with
the battery cell, and for the application of surface pressure to
the solid-state battery.
[0109] The material which changes in volume by heat is not
particularly limited, and examples thereof include polypropylene,
polyethylene terephthalate resins, and the like.
[0110] <Module Component>
The module component constituting the solid-state battery module of
the present invention is not particularly limited, and it may be
any component required for a normal battery module. For example,
the module component is exemplified by a bus bar, a thermistor, a
harness, a voltage detection line, a battery case fixing member, a
cell voltage and temperature monitoring unit and the like, and in
the present invention, the module component may be at least one
selected from the group consisting of those listed above.
[0111] [Arrangement of Module Component]
The module component constituting the solid-state battery module of
the present invention is arranged in the recess formed in the
battery case of the battery constituting the module. In the present
invention, it is sufficient that at least a part of the various
module components is arranged.
[0112] In the present invention, the module component is arranged
in the recess formed in the region which corresponds to the
residual space in the conventional battery. This makes it possible
to reduce the volume of the entire battery module, and consequently
to improve the energy density of the battery module.
Further, since there is no residual space in the battery case, the
displacement, peeling or the like of the battery cell due to
vibration or the like can be suppressed.
[0113] Referring to the battery module 100, which is an embodiment
of the present invention, the outer shape of the battery case 103
conforms to the outer shape of the battery cell 102, and the recess
is formed in the battery case 103 between the convex portion for
storing the positive electrode tab 104 and the convex portion for
storing the negative electrode tab 109, as shown in FIG. 2(b).
In other words, the upper face of the battery cell 102 has a shape
in which the recess is present in the region corresponding to the
residual space in the conventional battery.
[0114] In FIG. 2(b), which is a cross-sectional view of the
solid-state battery module according to an embodiment of the
present invention, the thermistor 108, which is a module component,
is disposed in the recess formed between the convex portion for
storing the positive electrode tab 104 and the convex portion for
storing the negative electrode tab 109. Further, the two terminals
105 are arranged, with one of the terminals 105 being electrically
connected to the convex portion for storing the positive electrode
tab 104 and the other to the convex portion for storing the
negative electrode tab 109. Other module components, i.e., the bus
bar 106, and the voltage detection line 107 are arranged so as to
line up with the terminals 105.
[0115] <Applications of Solid-State Battery Modules>
The solid-state battery module of the present invention can be used
in various apparatuses. The solid-state battery module of the
present invention has a small volume, and high energy density, and
is unlikely to cause terminal displacement or the like due to
vibration. Therefore, the solid-state battery module of the present
invention can be suitably used, for example, as a power source for
electric vehicles and hybrid vehicles, and the like, as well as in
portable devices.
EXPLANATION OF REFERENCE NUMERALS
[0116] 100, 200 battery module [0117] 101, 201 battery [0118] 102,
202 battery cell [0119] 103, 203 battery case [0120] 104, 204
positive electrode tab [0121] 105, 205 terminal [0122] 106, 206 bus
bar [0123] 107, 207 voltage detection line [0124] 108, 208
thermistor [0125] 109, 209 negative electrode tab [0126] 110, 210
module component [0127] 111 gap [0128] 112 pressing portion [0129]
113, 213 top cover [0130] 114, 214 binding bar [0131] 115, 215
lower plate [0132] 116 fin [0133] 120 expansion material [0134] 216
separator [0135] 217 end plate [0136] 218 thermally conductive
material
* * * * *