Battery module

Abstract

The main object of the present disclosure is to provide a battery module capable of inhibiting heat conduction between battery cells at the time of heat generation. In the present disclosure, the above object is achieved by providing a battery module having a plurality of battery cells arranged in a thickness direction, the battery module having an elastic member between adjacent battery cells, the elastic member being provided with a resin aggregate having thermal expansibility, the resin aggregate being arranged so as to include the center of the battery cell when viewed in the thickness direction, the resin aggregate having an expansion start temperature of 80°C or higher, and the resin aggregate having a thermal conductivity of 0.5 W / m·K or lower after expansion.

Description

Technical Field

[0001] This disclosure relates to battery modules. Background Technology

[0002] A battery module having multiple battery cells in the thickness direction is known, wherein each battery cell sequentially comprises a positive current collector, a positive active material layer, an electrolyte layer, a negative active material layer, and a negative current collector. For example, Patent Document 1 discloses a battery module having a first heat transfer member and a first thermally expanding material disposed between adjacent battery cells. Patent Document 2 discloses a battery module having an elastic member disposed between adjacent battery cells. Patent Document 3 discloses a battery pack structure having a heat insulation member disposed between battery cells. Patent Document 4 discloses a battery having a thermally expanding refractory material disposed between adjacent battery modules. Patent Document 5 discloses a battery pack having a separator with protrusions disposed between adjacent battery cells.

[0003] Existing technical documents

[0004] Patent Document 1: International Publication No. 2019 / 151037

[0005] Patent document 2: Japanese Patent Application Publication No. 2016-152072

[0006] Patent Document 3: Japanese Patent Application Publication No. 2015-079655

[0007] Patent document 4: Japanese Patent Application Publication No. 2017-182898

[0008] Patent Document 5: Japanese Patent Application Publication No. 2011-076779 Summary of the Invention

[0009] In a battery module with multiple stacked battery cells, if one battery cell heats up, adjacent battery cells may also heat up due to heat conduction. This disclosure was made in view of the above situation, and its main objective is to provide a battery module that can suppress heat conduction between battery cells when they are heated.

[0010] To address the aforementioned issues, this disclosure provides a battery module having a plurality of battery cells arranged along the thickness direction. The battery module has an elastic member between adjacent battery cells, and a thermally expandable resin composition is disposed on the elastic member. When viewed from above along the thickness direction, the resin composition is arranged to include the center of the battery cells. The expansion initiation temperature of the resin composition is 80°C or higher, and the thermal conductivity of the expanded resin composition is 0.5 W / m·K or lower.

[0011] According to this disclosure, by arranging an elastic member having a predetermined resin composition between adjacent battery cells, a battery module is formed that can suppress heat conduction between battery cells when heat is generated.

[0012] In the above disclosure, the resin composition can be disposed in the groove of the elastic member.

[0013] In the above disclosure, the resin composition can be disposed in the through portion of the elastic member.

[0014] In the above disclosure, when the thickness of the elastic member is set as T1 and the thickness of the resin composition is set as T2, the ratio of T2 to T1 (T2 / T1) can be 35% or more.

[0015] In the above disclosure, when viewed from above along the thickness direction, the elastic member is rectangular in shape. When the direction parallel to the long side is defined as the first direction, the direction orthogonal to the first direction is defined as the second direction, the length of the elastic member in the first direction is defined as X1, the length of the resin composition in the first direction is defined as X2, the length of the elastic member in the second direction is defined as Y1, and the length of the resin composition in the second direction is defined as Y2, the ratio of X2 to X1 (X2 / X1) and the ratio of Y2 to Y1 (Y2 / Y1) can be 25% or more.

[0016] In the above disclosure, X2 / X1 and Y2 / Y1 can each be 30% or more.

[0017] In the above disclosure, X2 / X1 and Y2 / Y1 can each be less than 50%.

[0018] In the above disclosure, when viewed from above along the thickness direction, if the area of ​​the region defined from the outer edge of the elastic member is set as S1 and the area of ​​the region defined from the outer edge of the resin composition is set as S2, the ratio of S2 to S1 (S2 / S1) can be 6.25% or more and 25% or less.

[0019] In the above disclosure, the elastic member may have a raised or recessed pattern on its surface.

[0020] In the above disclosure, the raised or recessed pattern can be comb-like, striped, or dotted.

[0021] In this disclosure, there is an effect of suppressing heat conduction between battery cells when heat is generated. Attached Figure Description

[0022] Figure 1This is a schematic side view illustrating the battery module in this disclosure.

[0023] Figure 2 These are schematic top views and schematic cross-sectional views illustrating the elastic members and resin compositions of this disclosure.

[0024] Figure 3 This is a schematic side view illustrating the battery module in this disclosure.

[0025] Figure 4 This is a schematic cross-sectional view illustrating the elastic member and resin composition of this disclosure.

[0026] Figure 5 This is a schematic top view illustrating the elastic member and resin composition of this disclosure.

[0027] Figure 6 This is a schematic cross-sectional view illustrating the elastic member and resin composition of this disclosure.

[0028] Figure 7 This is a schematic top view illustrating the elastic member and resin composition of this disclosure.

[0029] Figure 8 This is a schematic cross-sectional view illustrating a battery cell in this disclosure.

[0030] Explanation of reference numerals in the attached figures

[0031] 1… Battery cell

[0032] 2…Elastic members

[0033] 3…Resin composition

[0034] 10… Battery Module

[0035] 11… Positive electrode active material layer

[0036] 12…Negative electrode active material layer

[0037] 13…Electrolyte layer

[0038] 14…Positive current collector

[0039] 15… Negative current collector Detailed Implementation

[0040] The battery module of this disclosure will now be described in detail with the aid of accompanying drawings. The figures shown below are schematic diagrams, and the size and shape of the parts have been appropriately exaggerated for ease of understanding.

[0041] Figure 1 This is a schematic side view illustrating the battery module in this disclosure. Figure 1 The battery module 10 shown has a diameter D along the thickness direction. TMultiple battery cells 1 (battery cells 1a to 1e) are configured. In addition, the battery module 10 has elastic members 2 between adjacent battery cells 1. Figure 1 In the battery cell, elastic member 2a is disposed between battery cell 1a and battery cell 1b, elastic member 2b is disposed between battery cell 1b and battery cell 1c, elastic member 2c is disposed between battery cell 1c and battery cell 1d, and elastic member 2d is disposed between battery cell 1d and battery cell 1e.

[0042] Figure 2 (a) is an example Figure 1 A schematic top view of the elastic component (a schematic top view taken along the thickness direction). Figure 2 (b) is Figure 2 (a) AA section view, Figure 2 (c) is Figure 2 (a) BB cross-section diagram. For example... Figure 2 As shown in (b), a resin component 3 with thermal expansion properties is disposed in the groove 21 of the elastic member 2, such as... Figure 2 As shown in (a), the resin composition 3 is arranged in a central C that includes the battery cell (not shown). Additionally, Figure 2 (b) The resin component 3 shown is not included in the elastic member 2, and at least a portion of it is exposed from the elastic member 2.

[0043] According to this disclosure, by arranging an elastic member having a predetermined resin composition between adjacent battery cells, a battery module is formed that can suppress heat conduction between battery cells when heat is generated. Figure 3 The effects of this disclosure will be explained in more detail. Figure 3 Show Figure 1 The battery module when the battery cell 1c heats up and expands.

[0044] like Figure 3 As shown, when battery cell 1c heats up and expands, the heat from battery cell 1c is transferred to the resin components 3b and 3c disposed on elastic members 2b and 2c, causing the resin components 3b and 3c to expand. As a result, in the thickness direction D... T Above, the expanded battery cell 1c can be spaced further apart from adjacent battery cells 1b and 1d. Specifically, the resin components 3b and 3c, along the thickness direction D... T When viewed from above, the battery cell 1c is arranged in such a way that the center C (the most expanded point) is included, thus effectively increasing the distance between the expanded battery cell 1c and the adjacent battery cells 1b and 1d.

[0045] Furthermore, resin components 3b and 3c exhibit low thermal conductivity after expansion, thus suppressing heat transfer from battery cell 1c to battery cells 1b and 1d via resin components 3b and 3c. Additionally, resin component 3c expands due to heat, such as... Figure 3 As shown, when a space (air layer) is formed between battery cell 1c and elastic member 2c as a heat insulation layer, heat transfer from battery cell 1c to battery cell 1d can be suppressed. Similarly, the resin composition 3b expands due to heat, as... Figure 3 As shown, when a space (air layer) is formed between the elastic member 2b and the battery cell 1b as a heat insulation layer, heat transfer from the battery cell 1c and the elastic member 2b to the battery cell 1b can be suppressed. Furthermore, as... Figure 3 As shown, when battery cell 1c expands, elastic members 2a and 2d (elastic members disposed on the opposite side of the expanded battery cell 1c in adjacent battery cells 1b and 1d) contract, thereby suppressing the overall expansion of the battery module and suppressing the deformation of adjacent battery cells 1b and 1d.

[0046] 1. Elastic components and resin composition

[0047] The battery module of this disclosure has elastic members between adjacent battery cells. Preferably, the battery module has multiple elastic members. Specifically, when the battery module has three or more battery cells, there are multiple elastic members between adjacent battery cells, and it is preferable to provide elastic members for all of them. Furthermore, the elastic members of this disclosure are made of a resin composition with thermal expansion properties.

[0048] The expansion initiation temperature of the resin composition is typically above 80°C, but can be above 90°C or even above 100°C. If the expansion initiation temperature is too low, unintentional expansion of the resin composition can easily occur. On the other hand, there is no particular upper limit to the expansion initiation temperature of the resin composition, but if the expansion initiation temperature is too high, it may not be able to adequately suppress heat conduction between battery cells during heating. The expansion initiation temperature of the resin composition is not particularly limited, for example, it can be below 170°C. The expansion initiation temperature of the resin composition refers to the temperature at which the volume of the resin composition reaches 1.5 times its original volume at 25°C. The expansion initiation temperature can be adjusted by changing the type and composition of materials (e.g., resin and expansive materials) in the resin composition.

[0049] Furthermore, the thermal conductivity of the resin composition after expansion is typically below 0.5 W / m·K, and can also be below 0.3 W / m·K. On the other hand, there is no particular limitation on the lower limit of thermal conductivity, but if the thermal conductivity is too low, the range of usable resin compositions narrows. The thermal conductivity of the resin composition after expansion can be determined using the circular plate heat flow meter method according to ASTM E1530. The thermal conductivity after expansion can be adjusted by changing the type and composition of materials in the resin composition (e.g., resin and expansive material). Additionally, the thermal conductivity of the resin composition before expansion can be higher, the same, or lower than the thermal conductivity after expansion, but is mostly higher.

[0050] The volume expansion rate of the resin composition can be, for example, more than 2 times, more than 5 times, or more than 10 times. If the volume expansion rate is too small, it may not be able to adequately suppress heat conduction between battery cells when generating heat. On the other hand, there is no particular upper limit to the volume expansion rate of the resin composition, but if the volume expansion rate is too large, the range of resin compositions that can be used becomes narrower.

[0051] The resin composition disclosed herein includes, for example, a resin and an expansive material. Examples of the aforementioned resins include thermoplastic resins, thermosetting resins, and elastomer resins. Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and thermoplastic polyurethane. Examples of thermosetting resins include phenolic resins, epoxy resins, thermosetting polyurethanes, urea resins, and melamine resins. Examples of elastomer resins include silicone rubber, fluororubber, and acrylonitrile butadiene rubber. The resin composition may contain only one type of resin or may contain two or more types of resins.

[0052] Expansive materials are materials that expand due to heat. Examples of expansive materials include layered inorganic substances such as vermiculite, kaolin, mica, and thermally expandable graphite. The content of the expansive material is not particularly limited, but is, for example, more than 1 part by weight and less than 50 parts by weight relative to 100 parts by weight of resin.

[0053] On the other hand, the elastic component in this disclosure is not particularly limited to any elastic component, such as rubber or polyurethane. The elastic component can also be a component that does not exhibit thermal expansion. "A component that does not exhibit thermal expansion" means a component whose volume increase rate is less than 1.5 times when heated from room temperature to its melting point. Furthermore, for example, if the elastic component is porous, its volume may sometimes decrease when heated from room temperature to its melting point. Additionally, the thermal conductivity of the elastic component relative to the thermal conductivity of the expanded resin composition can be higher, the same, or lower.

[0054] Next, use Figure 2 , Figures 4-7The structure of the elastic component and the structure of the resin composition are described. For example... Figure 2 As shown in (a), the resin composition 3 is arranged with the center C containing the battery cell (not shown). Since the resin composition is arranged with the center (the most expanded point) containing the battery cell, as described above... Figure 3 As shown, this effectively increases the distance between the expanded battery cell 1c and adjacent battery cells 1b and 1d. In this disclosure, the center of the battery cell refers to the centroid of the face of the battery cell opposite to the resin composition.

[0055] like Figure 4 As shown in (a), the resin component 3 can also be disposed in the groove 21 of the elastic member 2. In this case, even after the resin component 3 expands, the reaction force of the expansion is applied to the adjacent battery cell (disposed of in) through the entire elastic member 2, including the bottom surface region of the groove 21. Figure 4 (a) The lower battery cell, thus it can suppress the deformation of adjacent battery cells.

[0056] Here, as Figure 4 As shown in (a), the thickness of the elastic member 2 is set to T1, and the thickness of the resin composition 3 is set to T2. The ratio of T2 to T1 (T2 / T1) is, for example, 35% or more, 40% or more, or 45% or more. If T2 / T1 is too small, it may not be able to sufficiently suppress heat conduction between battery cells when heat is generated. On the other hand, as Figure 4 As shown in (a), when the elastic member 2 has a groove 21, T2 / T1 can be less than 1. In this case, T2 / T1 is, for example, less than 90%, less than 80%, or less than 70%. If T2 / T1 is too large, deformation may occur in adjacent battery cells.

[0057] in addition, Figure 4 In (a), the top surface of the elastic member 2 and the top surface of the resin component 3 are on the same plane, but as Figure 4 As shown in (b), the top surface of the resin component 3 can also be located at a lower position than the top surface of the elastic member 2 (the inner side position). In this case, a space is created on the top surface of the resin component 3, thus providing the advantage of high heat dissipation during normal use. On the other hand, as Figure 4 As shown in (c), the top surface of the resin component 3 can also be located at a higher position than the top surface of the elastic member 2 (the outer side position). In this case, the resin component 3 is disposed between adjacent battery cells in a compressed state, and therefore expands significantly when heated, effectively increasing the distance between the expanded battery cells and adjacent battery cells. Furthermore, Figure 4 In case (c), T2 / T1 can be less than 1, 1, or greater than 1.

[0058] On the other hand, such as Figure 4 As shown in (d), the resin component 3 can be disposed in the through portion 22 of the elastic member 2. In this case, after the resin component 3 expands, it can effectively increase the distance between the expanded battery cell and the adjacent battery cell. Furthermore, Figure 4 In (d), T2 / T1 is 1, but if Figure 4 As shown in (e), T2 / T1 can be less than 1, as... Figure 4 As shown in (f), T2 / T1 can also be greater than 1. Additionally, Figure 4 In (d), the top and bottom surfaces of the elastic member 2 are on the same plane as the top and bottom surfaces of the resin component 3. Figure 4 In (e), the top surface of the resin composition 3 is located at a lower position than the top surface of the elastic member 2 (the position on the inner side), and the bottom surface of the resin composition 3 is located at a higher position than the bottom surface of the elastic member 2 (the position on the inner side). Figure 4 In (f), the top surface of the resin composition 3 is located at a higher position than the top surface of the elastic member 2 (the position on the outer side), and the bottom surface of the resin composition 3 is located at a lower position than the bottom surface of the elastic member 2 (the position on the outer side).

[0059] like Figure 5 As shown, when the top view shape of the elastic member 2 (the shape viewed from above along the thickness direction) is rectangular, the direction parallel to the long side is designated as the first direction D1, and the direction orthogonal to the first direction D1 is designated as the second direction D2. Furthermore, when the top view shape of the elastic member is square, either side is considered as the aforementioned long side. Figure 5 In the middle, the left and right directions are equivalent to the first direction D1, and the up and down directions are equivalent to the second direction D2. Additionally, as... Figure 5 As shown, the length of the elastic member 2 in the first direction D1 is defined as X1, the length of the resin composition 3 in the first direction D1 is defined as X2, the length of the resin composition 3 in the second direction D2 is defined as Y1, and the length of the resin composition 3 in the second direction D2 is defined as Y2. X2 / X1 and Y2 / Y1 are, for example, 25% or more, and may also be 30% or more. If X2 / X1 and Y2 / Y1 are too small, stress concentration will occur when the resin composition 3 expands, potentially causing deformation of adjacent battery cells. On the other hand, X2 / X1 and Y2 / Y1 are, for example, 75% or less, and may also be 50% or less. If X2 / X1 and Y2 / Y1 are too large, the area of ​​the space (air layer) that functions as a heat insulation layer may be relatively reduced after the resin composition 3 expands.

[0060] The top view shape of the elastic member is, for example, rectangular, preferably square or rectangular. Examples of top view shapes of the resin composition include rectangles such as rectangles and squares, circles such as circles and ellipses. When the top view shape of the resin composition is circular, the lengths Y1 and Y2 of the resin composition refer to the maximum values ​​of the lengths in the first and second directions, respectively.

[0061] Furthermore, when viewing the elastic member and the resin composition from above along the thickness direction, the area of ​​the region defined from the outer edge of the elastic member is designated as S1, and the area of ​​the region defined from the outer edge of the resin composition is designated as S2. The ratio of S2 to S1 (S2 / S1) is, for example, 6.25% or more, and may also be 11.1% or more. On the other hand, S2 / S1 is, for example, 56.25% or less, and may also be 25% or less.

[0062] like Figure 6 As shown in (a) to (d), the elastic member 2 may have a raised or recessed pattern 23 on its surface. By providing the raised or recessed pattern 23, heat dissipation is improved. Figure 6 In (a) to (c), the raised and recessed pattern 23 is formed only on one surface of the elastic member 2. Figure 6 In (a), the top surface of the resin component 3 and the top surface of the embossed pattern 23 are on the same plane. Figure 6 In (b), the top surface of the resin composition 3 and the bottom surface of the raised / recessed pattern 23 are on the same plane. Alternatively, although not shown, the top surface of the resin composition may also be located between the top and bottom surfaces of the raised / recessed pattern. Furthermore, as... Figure 6 As shown in (c), a raised or recessed pattern can also be formed on the surface (one side) of the resin composition 3.

[0063] Figure 6 In (d) to (f), concave and convex patterns 23 are formed on both sides of the elastic member 2. Figure 6 In (d), the top and bottom surfaces of the resin component 3 and the top and bottom surfaces of the elastic component 2 are on the same plane. Figure 6 In (e), the top surface of the resin component 3 is located at a lower position than the top surface of the elastic member 2 (the inner side position), and the bottom surface of the resin component 3 is located at a higher position than the bottom surface of the elastic member 2 (the inner side position). Additionally, as... Figure 6 As shown in (f), a raised or recessed pattern can also be formed on the surface (both sides) of the resin composition 3.

[0064] The top view shape of the embossed pattern 23 is not particularly limited, and can be as follows: Figure 7 (a) shows a comb-like shape, which can be used as follows: Figure 7 (b) shows a striped pattern, which can also be as shown in... Figure 7 (c) shows a dotted pattern.

[0065] 2. Battery Unit

[0066] Figure 8 This is a schematic cross-sectional view illustrating a battery cell in this disclosure. Figure 8 The battery cell 1 shown includes: a positive electrode active material layer 11, a negative electrode active material layer 12, an electrolyte layer 13 formed between the positive electrode active material layer 11 and the negative electrode active material layer 12, a positive electrode current collector 14 for collecting current from the positive electrode active material layer 11, a negative electrode current collector 15 for collecting current from the negative electrode active material layer 12, and a battery casing 16 for housing them. Typically, the battery cell is a lithium-ion secondary battery.

[0067] (1) Positive electrode active material

[0068] The positive electrode active material layer contains at least a positive electrode active material, and may also contain at least one of a conductive material, a binder, and an electrolyte, depending on the requirements. Examples of positive electrode active materials include LiCoO2 and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other oxide active substances.

[0069] Examples of conductive materials include carbon materials such as acetylene black, Ketjen black, VGCF, and graphite. Examples of adhesives include fluorinated adhesives such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), and rubber-based adhesives such as acrylate butadiene rubber (ABR) and styrene butadiene rubber (SBR). Electrolytes are described in "(3) Electrolyte Layer".

[0070] (2) Negative electrode active material layer

[0071] The negative electrode active material layer contains at least a negative electrode active material, and may contain at least one of conductive material, binder, and electrolyte as needed. Examples of negative electrode active materials include, for example, intermediate carbon microspheres (MCMB), highly oriented graphite (HOPG), and Li4Ti5O. 12 Metal oxide active materials, such as In, Al, Si, Sn, etc. Conductive materials, binders, and electrolytes are the same as those described in "(1) Positive electrode active material layer" above.

[0072] (3) Electrolyte layer

[0073] The electrolyte layer is formed between the positive electrode active material layer and the negative electrode active material layer. The electrolyte constituting the electrolyte layer can be a liquid electrolyte (electrolyte) or a solid electrolyte. Electrolytes may contain, for example, Li salts and non-aqueous solvents. Examples of Li salts include LiPF6, LiBF4, LiN(CF3SO2)2, and LiN(C2F5SO2)2. Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), and chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). Solid electrolytes include organic solid electrolytes such as polymer electrolytes and gel electrolytes, and inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes.

[0074] (4) Other structures

[0075] The battery cell of this disclosure typically has a positive current collector for collecting current in the positive electrode active material layer and a negative current collector for collecting current in the negative electrode active material layer. Additionally, the battery cell of this disclosure has a battery casing. These components can be general components.

[0076] 3. Battery Module

[0077] The number of battery cells in the battery module is not particularly limited and can be appropriately set according to the intended use of the battery module. Examples of applications for the battery module include power supplies for vehicles such as hybrid electric vehicles, electric vehicles, gasoline vehicles, and diesel vehicles. It is particularly preferred for use as a power supply for driving hybrid electric vehicles or electric vehicles. Furthermore, the battery module of this disclosure can be used as a power supply for mobile bodies other than vehicles (e.g., railways, ships, and aircraft), and also as a power supply for electrical appliances such as information processing devices.

[0078] Furthermore, this disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and all solutions that have the same technical concept as those described in the scope of the patent claims of this disclosure and that achieve the same effect are included within the technical scope of this disclosure.

[0079] Example

[0080] [Example 1]

[0081] (Preparation of elastic components with resin composition)

[0082] like Figure 2As shown in (b), an elastic member 2 with a surface having a raised / lowered pattern 23 and a groove 21 is prepared, along with a resin composition 3 disposed in the groove 21. Viewed from above along the thickness direction, the resin composition 3 is disposed such that it includes the center of the battery cell. Furthermore, the ratio (T2 / T1) of the thickness T2 of the resin composition 3 to the thickness T1 of the elastic member 2 is 1 / 2 (=50%). Additionally, as... Figure 6 As shown, the ratio of the length X2 of the resin component 3 in the first direction to the length X1 of the elastic member 2 (X2 / X1) is 1 / 4 (=25%), and the ratio of the length Y2 of the resin component 3 in the second direction to the length Y1 of the elastic member 2 (Y2 / Y1) is 1 / 4 (=25%).

[0083] Rubber is used as the material for the elastic component. On the other hand, the resin composition is prepared as follows: Polypropylene is used as the resin, and thermally expandable graphite is used as a layered inorganic material with thermal expansion. The mixture of these materials, in a weight ratio of 100:20, is heated and molded at a low temperature. The expansion initiation temperature of the resin composition is 160°C, the volume expansion rate during expansion is 300%, and the thermal conductivity after expansion is 0.5 W / m·K.

[0084] (Battery module fabrication)

[0085] Using LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 The battery cell was fabricated using O2 as the positive electrode active material, graphite as the negative electrode active material, and a solution obtained by dissolving LiPF6 at a concentration of 1 mol / L in a solvent composed of equal volumes of ethylene carbonate (EC) and diethyl carbonate (DEC) as the electrolyte.

[0086] Prepare 5 fabricated battery cells, and arrange elastic members formed of resin components between adjacent battery cells to fabricate... Figure 1 The battery module shown.

[0087] [Examples 2-3]

[0088] The battery module was fabricated in the same manner as in Example 1, except that the dimensions (T2 / T1, X2 / X1 and Y2 / Y1) of the resin components were changed to the values ​​shown in Table 1.

[0089] [Comparative Example 1]

[0090] The battery module was manufactured in the same manner as in Example 1, except that no groove was provided in the elastic member and no resin component was provided.

[0091] [evaluate]

[0092] (Prick test)

[0093] Under the following conditions, a nail-punching test was performed on the battery modules obtained in Examples 1-3 and Comparative Example 1, causing the central unit ( Figure 1 Battery cell 1c was short-circuited, intentionally causing it to smoke. Then, for adjacent cells ( Figure 1 The battery cells 1b and 1d were evaluated for any chain-like smoke and cell deformation. The results are shown in Table 1.

[0094] • Conditions for the nail puncture test

[0095] SOC (State of Charge): 100%

[0096] Nail: φ6mm, apex angle 60°

[0097] Spike speed: 2mm / second

[0098] Spike location: Gas discharge valve

[0099] Table 1

[0100]

[0101] As shown in Table 1, in Examples 1-3, no chain-reaction smoke from adjacent cells was observed, and heat conduction from the central battery cell was suppressed. On the other hand, in Comparative Example 1, chain-reaction smoke from adjacent cells was observed. Thus, it was confirmed that by using an elastic member having a predetermined resin composition, heat conduction between battery cells during heating can be suppressed.

[0102] Furthermore, in Examples 1 and 3, deformation occurred in adjacent units, but in Example 2, no deformation occurred in adjacent units. In Example 1, the dimensions (X2 / X1, Y2 / Y1) of the resin composition were small, so the expansion stress was concentrated in a portion of the adjacent units. In Example 3, the resin composition was arranged with a through-elastic member, so the expansion stress was concentrated in a portion of the adjacent units. Based on these results, it is inferred that deformation occurred in adjacent units. In contrast, in Example 2, the dimensions (T2 / T1, X2 / X1, Y2 / Y1) of the resin composition were appropriate, so it is inferred that no deformation occurred in adjacent units.

Claims

1. A battery module, comprising: Multiple battery cells arranged along the thickness direction. The elastic members arranged between adjacent battery cells, and A thermally expandable resin composition disposed in the groove of the elastic member. in, Viewed from above along the thickness direction, the resin composition is arranged such that it includes the center of the battery cell. The expansion initiation temperature of the resin composition is above 80°C. The thermal conductivity of the resin component after expansion is below 0.5 W / m·K. The resin composition contains a thermoplastic resin and a layered inorganic material as an expansive material. The elastic member has a raised or recessed pattern on one surface in the thickness direction. The resin component is disposed in a groove formed on the surface of the elastic member having the raised and recessed pattern. When the thickness of the elastic member is set to T1 and the thickness of the resin composition is set to T2, the ratio of T2 to T1, T2 / T1, is 50% or more and 70% or less. When viewed from above along the thickness direction, the elastic member has a rectangular shape. With the direction parallel to the long side designated as the first direction, the direction orthogonal to the first direction designated as the second direction, the length of the elastic member in the first direction designated as X1, the length of the resin composition in the first direction designated as X2, the length of the elastic member in the second direction designated as Y1, and the length of the resin composition in the second direction designated as Y2, the ratio of X2 to X1 (X2 / X1) and the ratio of Y2 to Y1 (Y2 / Y1) are both 25% or more and 50% or less.

2. The battery module according to claim 1, wherein X2 / X1 and Y2 / Y1 are respectively 30% or more and 50% or less.

3. The battery module according to claim 1, wherein, when viewed from above along the thickness direction, the area of ​​the region defined by the outer edge of the elastic member is set as S1, and the area of ​​the region defined by the outer edge of the resin composition is set as S2, the ratio of S2 to S1, S2 / S1, is 6.25% or more and 25% or less.

4. The battery module according to claim 1, wherein the embossed pattern is comb-shaped, striped, or dotted.

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