Battery Module

Abstract

To provide a battery module capable of restraining heat conduction between battery cells in heat generation.SOLUTION: The present disclosure provides a battery module including a plurality of battery cells arranged along with a thickness direction. The battery module has an elastic member between the adjacent battery cells battery cells. A thermally expandable resin composition body is arranged in the elastic member. In a plan view along with the thickness direction, the resin composition body is arranged to include a center of the battery cell. An expansion start temperature of the resin composition body is 80°C or more, and heat conductivity after expansion of the resin composition body is 0.5 W / m K or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery module. [Background technology]

[0002] There is known a battery module having a plurality of battery cells in the thickness direction, each having a positive electrode current collector, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order. For example, Patent Document 1 discloses a battery module having a first heat transfer member and a first thermal expansion material arranged between adjacent battery cells. Patent Document 2 discloses a battery module in which an elastic member is arranged between adjacent battery cells. Patent Document 3 discloses a battery assembly structure in which a heat insulating member is arranged between battery cells. Patent Document 4 discloses a battery in which a thermally expandable fireproof material is arranged between adjacent battery modules. Patent Document 5 discloses a battery pack in which a separator having a protrusion is arranged between adjacent battery cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 151037 [Patent Document 2] JP 2016-152072 A [Patent Document 3] JP 2015-079655 A [Patent Document 4] JP 2017-182898 A [Patent Document 5] JP 2011-076779 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery module in which multiple battery cells are stacked, when one battery cell generates heat, the adjacent battery cells may also generate heat due to thermal conduction. The present disclosure has been made in view of the above-mentioned circumstances, and has a primary object to provide a battery module that can suppress thermal conduction between battery cells when heat is generated. [Means for solving the problem]

[0005] In order to solve the above problems, the present disclosure provides a battery module having a plurality of battery cells arranged along a thickness direction, the battery module having an elastic member between adjacent battery cells, a thermally expandable resin composition arranged in the elastic member, the resin composition being arranged so as to include the center of the battery cell when viewed in a plan view along the thickness direction, an expansion start temperature of the resin composition being 80°C or higher, and a thermal conductivity of the resin composition after expansion being 0.5 W / m·K or lower.

[0006] According to the present disclosure, by disposing an elastic member having a prescribed resin composition between adjacent battery cells, a battery module is obtained that can suppress thermal conduction between the battery cells when heat is generated.

[0007] In the above disclosure, the resin composition may be disposed in a groove portion of the elastic member.

[0008] In the above disclosure, the resin composition may be disposed in the through-hole of the elastic member.

[0009] In the above disclosure, when the thickness of the elastic member is T1 and the thickness of the resin composition is T2, the ratio of T2 to T1 (T2 / T1) may be 35% or more.

[0010] In the above disclosure, when viewed in a plane along the thickness direction, the shape of the elastic member is rectangular, a direction parallel to a long side is a first direction, a direction perpendicular to the first direction is a second direction, and the length of the elastic member in the first direction is X1, the length of the resin composition in the first direction is X2, the length of the elastic member in the second direction is Y1, and the length of the resin composition in the second direction is Y2. In this case, the ratio of X2 to X1 (X2 / X1) and the ratio of Y2 to Y1 (Y2 / Y1) may each be 25% or more.

[0011] In the above disclosure, X2 / X1 and Y2 / Y1 may each be 30% or more.

[0012] In the above disclosure, X2 / X1 and Y2 / Y1 may each be 50% or less.

[0013] In the above disclosure, when viewed in a plane along the thickness direction, if the area of ​​a region defined from the outer edge of the elastic member is S1 and the area of ​​a region defined from the outer edge of the resin composition is S2, the ratio of S2 to S1 (S2 / S1) may be 6.25% or more and 25% or less.

[0014] In the above disclosure, the elastic member may have an uneven pattern on its surface.

[0015] In the above disclosure, the concave-convex pattern may be a comb-like, stripe-like or dot-like pattern. Effect of the Invention

[0016] The present disclosure provides an advantage in that it is possible to suppress thermal conduction between battery cells when heat is generated. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic side view illustrating a battery module according to the present disclosure. [Diagram 2] 1A and 1B are schematic plan views and schematic cross-sectional views illustrating an elastic member and a resin composition according to the present disclosure. [Diagram 3] FIG. 2 is a schematic side view illustrating a battery module according to the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating an example of an elastic member and a resin composition according to the present disclosure. [Diagram 5] 1 is a schematic plan view illustrating an example of an elastic member and a resin composition according to the present disclosure. [Figure 6] 1 is a schematic cross-sectional view illustrating an example of an elastic member and a resin composition according to the present disclosure. [Figure 7] 1 is a schematic plan view illustrating an example of an elastic member and a resin composition according to the present disclosure. [Figure 8] 1 is a schematic cross-sectional view illustrating a battery cell according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the battery module according to the present disclosure will be described in detail with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated for ease of understanding.

[0019] FIG 1 is a schematic side view illustrating a battery module according to the present disclosure. T The battery module 10 has a plurality of battery cells 1 (battery cells 1a to 1e) arranged along a line. The battery module 10 also has elastic members 2 between adjacent battery cells 1. In FIG. 1, an elastic member 2a is arranged between battery cell 1a and battery cell 1b, an elastic member 2b is arranged between battery cell 1b and battery cell 1c, an elastic member 2c is arranged between battery cell 1c and battery cell 1d, and an elastic member 2d is arranged between battery cell 1d and battery cell 1e.

[0020] Fig. 2(a) is a schematic plan view (schematic plan view when viewed in the thickness direction) illustrating the elastic member in Fig. 1, Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a), and Fig. 2(c) is a cross-sectional view taken along line BB in Fig. 2(a). As shown in Fig. 2(b), a resin composition 3 having thermal expansion properties is disposed in a groove portion 21 of the elastic member 2, and as shown in Fig. 2(a), the resin composition 3 is disposed so as to include a center C of a battery cell (not shown). The resin composition 3 shown in Fig. 2(b) is not encapsulated in the elastic member 2, and at least a portion of it is exposed from the elastic member 2.

[0021] According to the present disclosure, by disposing an elastic member having a predetermined resin composition between adjacent battery cells, a battery module is obtained that can suppress thermal conduction between the battery cells when heat is generated. The effects of the present disclosure will be explained in more detail with reference to Fig. 3. Fig. 3 shows a battery module in which the battery cell 1c in Fig. 1 generates heat and expands.

[0022] As shown in FIG. 3, when the battery cell 1c generates heat and expands, the heat of the battery cell 1c is transferred to the resin composition bodies 3b and 3c arranged in the elastic members 2b and 2c, causing the resin composition bodies 3b and 3c to expand. T In particular, the resin compositions 3b and 3c are arranged in the thickness direction D. T When viewed in a plane along the axis, the battery cell 1c is positioned to include the center C (the point that expands most), which effectively increases the distance between the expanded battery cell 1c and the adjacent battery cells 1b and 1d.

[0023] Furthermore, since the resin compositions 3b and 3c have low thermal conductivity after expansion, it is possible to suppress the heat of the battery cell 1c from being transferred to the battery cells 1b and 1d via the resin compositions 3b and 3c. Also, when the resin composition 3c expands due to heat and a space (air layer) is formed as a heat insulating layer between the battery cell 1c and the elastic member 2c as shown in FIG. 3, it is possible to suppress the heat of the battery cell 1c from being transferred to the battery cell 1d. Similarly, when the resin composition 3b expands due to heat and a space (air layer) is formed as a heat insulating layer between the elastic member 2b and the battery cell 1b as shown in FIG. 3, it is possible to suppress the heat of the battery cell 1c and the elastic member 2b from being transferred to the battery cell 1b. Also, as shown in FIG. 3, when the battery cell 1c expands, the elastic members 2a and 2d (elastic members arranged on the opposite side of the expanded battery cell 1c in the adjacent battery cells 1b and 1d) contract, which suppresses the expansion of the entire battery module and the deformation of the adjacent battery cells 1b and 1d.

[0024] 1. Elastic material and resin composition The battery module in the present disclosure has an elastic member between adjacent battery cells. The battery module preferably has a plurality of elastic members. Specifically, when the battery module has three or more battery cells, there are a plurality of spaces between adjacent battery cells, and it is preferable that an elastic member is disposed in all of the spaces. In addition, a resin composition having thermal expansion properties is disposed in the elastic member in the present disclosure.

[0025] The expansion start temperature of the resin composition is usually 80°C or higher, may be 90°C or higher, or may be 100°C or higher. If the expansion start temperature is too low, unintended expansion of the resin composition is likely to occur. On the other hand, the upper limit of the expansion start temperature of the resin composition is not particularly limited, but if the expansion start temperature is too high, there is a possibility that the thermal conduction between the battery cells during heat generation cannot be sufficiently suppressed. The expansion start temperature of the resin composition is not particularly limited, but is, for example, 170°C or lower. The expansion start temperature of the resin composition refers to the temperature at which the volume of the resin composition at 25°C becomes 1.5 times. The expansion start temperature can be adjusted by changing the type and composition of the materials (e.g., resin and expandable material) in the resin composition.

[0026] The thermal conductivity of the resin composition after expansion is usually 0.5 W / m·K or less, and may be 0.3 W / m·K or less. On the other hand, the lower limit of the thermal conductivity is not particularly limited, but if the thermal conductivity is too low, the range of selection of usable resin compositions becomes narrow. The thermal conductivity of the resin composition after expansion can be determined by a disk heat flow meter method in accordance with ASTM E1530. The thermal conductivity after expansion can be adjusted by changing the type and composition of the materials (e.g., resin and expandable material) in the resin composition. The thermal conductivity of the resin composition before expansion may be higher, the same, or lower than the thermal conductivity of the resin composition after expansion, but is often higher.

[0027] The volume expansion rate of the resin composition is, for example, 2 times or more, may be 5 times or more, or may be 10 times or more. If the volume expansion rate is too small, there is a possibility that the thermal conduction between the battery cells during heat generation cannot be sufficiently suppressed. On the other hand, the upper limit of the volume expansion rate of the resin composition is not particularly limited, but if the volume expansion rate is too large, the range of selection of usable resin compositions becomes narrow.

[0028] The resin composition in the present disclosure contains, for example, a resin and an expandable material. Examples of the resin include thermoplastic resins, thermosetting resins, and elastomer resins. Examples of the thermoplastic resins include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and thermoplastic polyurethane. Examples of the thermosetting resins include phenolic resins, epoxy resins, thermosetting polyurethanes, urea resins, and melamine resins. Examples of the 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.

[0029] The expandable material is a material that expands due to heat. Examples of the expandable material include layered inorganic materials such as vermiculite, kaolin, mica, and thermally expandable graphite. The content of the expandable material is not particularly limited, but is, for example, 1 part by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the resin.

[0030] On the other hand, the elastic member in the present disclosure is not particularly limited as long as it is a member having elasticity, and examples thereof include rubber and urethane. The elastic member may be a member having no thermal expansion. A "member having no thermal expansion" refers to a member whose volume increase rate is less than 1.5 times when heated from room temperature to the melting point. For example, when the elastic member is porous, the volume may decrease when heated from room temperature to the melting point. In addition, the thermal conductivity of the elastic member may be higher, the same, or lower than the thermal conductivity of the resin composition after expansion.

[0031] Next, the structure of the elastic member and the structure of the resin composition will be described with reference to Fig. 2 and Figs. 4 to 7. As shown in Fig. 2(a), the resin composition 3 is arranged so as to include the center C of the battery cell (not shown). Since the resin composition is arranged so as to include the center of the battery cell (the point of greatest expansion), it is possible to effectively increase the distance between the expanded battery cell 1c and the adjacent battery cells 1b, 1d, as shown in Fig. 3 above. In the present disclosure, the center of the battery cell refers to the center of gravity of the surface of the battery cell that faces the resin composition.

[0032] As shown in Fig. 4(a), the resin composition 3 may be disposed in a groove 21 of the elastic member 2. In this case, even if the resin composition 3 expands, the reaction force of the expansion is applied to an adjacent battery cell (the battery cell disposed on the lower side in Fig. 4(a)) via the entire elastic member 2 including the bottom region of the groove 21, so deformation of the adjacent battery cell can be suppressed.

[0033] Here, as shown in FIG. 4(a), the thickness of the elastic member 2 is T1, and the thickness of the resin composition 3 is T2. The ratio of T2 to T1 (T2 / T1) is, for example, 35% or more, may be 40% or more, or may be 45% or more. If T2 / T1 is too small, there is a possibility that the thermal conduction between the battery cells during heat generation cannot be sufficiently suppressed. On the other hand, as shown in FIG. 4(a), when the elastic member 2 has a groove portion 21, T2 / T1 may be smaller than 1. In this case, T2 / T1 is, for example, 90% or less, may be 80% or less, or may be 70% or less. If T2 / T1 is too large, there is a possibility that the adjacent battery cells will be deformed.

[0034] In addition, in FIG. 4(a), the top surface of the elastic member 2 and the top surface of the resin composition 3 are flush with each other, but as shown in FIG. 4(b), the top surface of the resin composition 3 may be located lower (inner) than the top surface of the elastic member 2. In this case, a space is generated above the top surface of the resin composition 3, which has the advantage of high heat dissipation during normal use. On the other hand, as shown in FIG. 4(c), the top surface of the resin composition 3 may be located higher (outer) than the top surface of the elastic member 2. In this case, the resin composition 3 is arranged in a compressed state between the adjacent battery cells, so that it expands significantly when heat is generated, and the distance between the expanded battery cell and the adjacent battery cell can be effectively increased. In addition, in the case of FIG. 4(c), T2 / T1 may be smaller than 1, may be 1, or may be larger than 1.

[0035] On the other hand, as shown in FIG. 4(d), the resin composition 3 may be disposed in the through-hole 22 of the elastic member 2. In this case, when the resin composition 3 expands, the distance between the expanded battery cell and the adjacent battery cell can be effectively increased. In FIG. 4(d), T2 / T1 is 1, but as shown in FIG. 4(e), T2 / T1 may be smaller than 1, and as shown in FIG. 4(f), T2 / T1 may be larger than 1. In FIG. 4(d), the top and bottom surfaces of the elastic member 2 and the top and bottom surfaces of the resin composition 3 are flush with each other. In FIG. 4(e), the top surface of the resin composition 3 is located lower (inner) than the top surface of the elastic member 2, and the bottom surface of the resin composition 3 is located higher (inner) than the bottom surface of the elastic member 2. In Figure 4(f), the top surface of the resin composition 3 is at a higher position (outer position) than the top surface of the elastic member 2, and the bottom surface of the resin composition 3 is at a lower position (outer position) than the bottom surface of the elastic member 2.

[0036] As shown in FIG. 5, when the shape of the elastic member 2 in plan view (the shape when viewed in plan along the thickness direction) is rectangular, the direction parallel to the long side is the first direction D1, and the direction perpendicular to the first direction D1 is the second direction D2. When the shape of the elastic member in plan view is square, any one of the sides is regarded as the long side. In FIG. 5, the left-right direction corresponds to the first direction D1, and the up-down direction corresponds to the second direction D2. Also, as shown in FIG. 5, the length of the elastic member 2 in the first direction D1 is X1, the length of the resin composition body 3 in the first direction D1 is X2, the length of the resin composition body 3 in the second direction D2 is Y1, and the length of the resin composition body 3 in the second direction D2 is Y2. X2 / X1 and Y2 / Y1 are, for example, 25% or more, and may be 30% or more, respectively. If X2 / X1 and Y2 / Y1 are too small, stress is concentrated when the resin composition body 3 expands, and deformation may occur in adjacent battery cells. On the other hand, X2 / X1 and Y2 / Y1 are, for example, 75% or less, and may be 50% or less, respectively. If X2 / X1 and Y2 / Y1 are too large, the area of ​​the space (air layer) that functions as a heat insulating layer after the resin composition 3 expands may become relatively small.

[0037] The planar shape of the elastic member is, for example, rectangular, and preferably rectangular or square. The planar shape of the resin composition may be, for example, rectangular, such as rectangular or square, or circular, such as perfect circle or ellipse. When the planar 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.

[0038] When the elastic member and the resin composition are viewed in a plan view along the thickness direction, the area of ​​a region defined by the outer edge of the elastic member is defined as S1, and the area of ​​a region defined by the outer edge of the resin composition is defined as S2. The ratio of S2 to S1 (S2 / S1) is, for example, 6.25% or more, and may be 11.1% or more. Meanwhile, S2 / S1 is, for example, 56.25% or less, and may be 25% or less.

[0039] As shown in Figs. 6(a) to (d), the elastic member 2 may have an uneven pattern 23 on its surface. Providing the uneven pattern 23 improves heat dissipation. In Figs. 6(a) to (c), the uneven pattern 23 is formed on only one surface of the elastic member 2. In Fig. 6(a), the top surface of the resin composition 3 and the top surface of the uneven pattern 23 are flush with each other. In Fig. 6(b), the top surface of the resin composition 3 and the bottom surface of the uneven pattern 23 are flush with each other. Although not shown, the top surface of the resin composition may be located midway between the top surface and the bottom surface of the uneven pattern. In addition, as shown in Fig. 6(c), an uneven pattern may be formed on the surface (one side) of the resin composition 3.

[0040] 6(d) to (f), a concave-convex pattern 23 is formed on both sides of the elastic member 2. In FIG. 6(d), the top and bottom surfaces of the resin composition 3 are flush with the top and bottom surfaces of the elastic member 2. In FIG. 6(e), the top surface of the resin composition 3 is located lower (inner position) than the top surface of the elastic member 2, and the bottom surface of the resin composition 3 is located higher (inner position) than the bottom surface of the elastic member 2. Also, as shown in FIG. 6(f), a concave-convex pattern may be formed on the surface (both sides) of the resin composition 3.

[0041] The planar shape of the uneven pattern 23 is not particularly limited, and may be a comb shape as shown in FIG. 7(a), a stripe shape as shown in FIG. 7(b), or a dot shape as shown in FIG. 7(c).

[0042] 2. Battery cells Fig. 8 is a schematic cross-sectional view illustrating a battery cell in the present disclosure. The battery cell 1 shown in Fig. 8 has 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 that collects current from the positive electrode active material layer 11, a negative electrode current collector 15 that collects current from the negative electrode active material layer 14, and a battery case 16 that houses them. The battery cell is typically a lithium ion secondary battery.

[0043] (1) Positive electrode active material layer The positive electrode active material layer contains at least a positive electrode active material, and may contain at least one of a conductive material, a binder, and an electrolyte, if necessary. Examples of the positive electrode active material include LiCoO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Examples of oxide active materials include O2.

[0044] Examples of the conductive material include carbon materials such as acetylene black, ketjen black, VGCF, and graphite. Examples of the binder include fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), and rubber-based binders such as acrylate butadiene rubber (ABR) and styrene butadiene rubber (SBR). The electrolyte is described in "(3) Electrolyte Layer."

[0045] (2) Negative electrode active material layer The negative electrode active material layer contains at least a negative electrode active material, and may contain at least one of a conductive material, a binder, and an electrolyte, if necessary. Examples of the negative electrode active material include carbon active materials such as mesocarbon microbeads (MCMB) and highly oriented graphite (HOPG), Li4Ti5O 12 and metal active materials such as In, Al, Si, Sn, etc. The conductive material, binder, and electrolyte are the same as those described in "(1) Positive electrode active material layer" above.

[0046] (3) Electrolyte layer The electrolyte layer is a layer formed between the positive electrode active material layer and the negative electrode active material layer. The electrolyte constituting the electrolyte layer may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The electrolytic solution contains, for example, a Li salt and a non-aqueous solvent. Examples of the Li salt include LiPF6, LiBF4, LiN(CF3SO2)2, and LiN(C2F5SO2)2. Examples of the non-aqueous solvent 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). Examples of the solid electrolyte 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 halogenated solid electrolytes.

[0047] (4) Other configurations The battery cell in the present disclosure generally includes a positive electrode current collector that collects current from the positive electrode active material layer and a negative electrode current collector that collects current from the negative electrode active material layer. The battery cell in the present disclosure also includes a battery case. These components may be made of general components.

[0048] 3. Battery module The number of battery cells in the battery module is not particularly limited and can be set appropriately depending on the application of the battery module. Examples of applications of the battery module include power sources for vehicles such as hybrid automobiles, electric automobiles, gasoline automobiles, and diesel automobiles. In particular, it is preferable to use the battery module as a driving power source for hybrid automobiles or electric automobiles. The battery module of the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), and may also be used as a power source for electrical products such as information processing devices.

[0049] The present disclosure is not limited to the above-described embodiment. The above-described embodiment is merely an example, and any configuration that is substantially the same as the technical idea described in the claims of the present disclosure and that exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0050] [Example 1] (Preparation of Elastic Member Having Resin Composition Placed Thereon) As shown in FIG. 2(b), an elastic member 2 having a concave-convex pattern 23 on its surface and a groove portion 21, and a resin composition 3 arranged in the groove portion 21 were prepared. The resin composition 3 was arranged so as to include the center of the battery cell when viewed in a plan view along the thickness direction. The ratio (T2 / T1) of the thickness T2 of the resin composition 3 to the thickness T1 of the elastic member 2 was set to 1 / 2 (=50%). As shown in FIG. 6, the ratio (X2 / X1) of the length X2 of the resin composition 3 to the length X1 of the elastic member 2 in the first direction was set to 1 / 4 (=25%), and the ratio (Y2 / Y1) of the length Y2 of the resin composition 3 to the length Y1 of the elastic member 2 in the second direction was set to 1 / 4 (=25%).

[0051] Rubber was used as the material for the elastic member. Meanwhile, the resin composition was prepared as follows. Polypropylene was used as the resin, and thermally expandable graphite was used as the layered inorganic material with thermal expansion. These were mixed in a weight ratio of 100:20 and molded at a low temperature. The resin composition had an expansion start temperature of 160°C, a volume expansion rate of 300% during expansion, and a thermal conductivity of 0.5 W / m K after expansion.

[0052] (Production of battery modules) LiNi as the positive electrode active material 1 / 3 Co 1 / 3 Mn 1 / 3 A battery cell was fabricated using O2, graphite as the negative electrode active material, and LiPF6 dissolved at a concentration of 1 mol / L in a solvent made by mixing equal volumes of ethylene carbonate (EC) and diethyl carbonate (DEC) as the electrolyte.

[0053] Five of the produced battery cells were prepared, and an elastic member with a resin composition disposed thereon was disposed between adjacent battery cells to produce a battery module as shown in FIG.

[0054] [Examples 2 to 3] A battery module was produced in the same manner as in Example 1, except that the sizes of the resin composition (T2 / T1, X2 / X1, Y2 / Y1) were changed to the values ​​shown in Table 1.

[0055] [Comparative Example 1] A battery module was produced in the same manner as in Example 1, except that no groove was provided in the elastic member and no resin composition was placed.

[0056] [evaluation] (Nail penetration test) A nail penetration test was carried out under the following conditions for the battery modules obtained in Examples 1 to 3 and Comparative Example 1, and the center cell (battery cell 1c in FIG. 1) was short-circuited to intentionally emit smoke. The adjacent cells (battery cells 1b and 1d in FIG. 1) were then evaluated for the presence or absence of chain smoke emission and cell deformation. The results are shown in Table 1. Nail penetration test conditions SOC(State of Charge):100% Nail: φ6mm, tip angle 60° Nail penetration speed: 2mm / sec Nail insertion location: Gas exhaust valve

[0057] [Table 1]

[0058] As shown in Table 1, in Examples 1 to 3, no chain smoke generation to adjacent cells was observed, and heat conduction from the central battery cell was suppressed. On the other hand, chain smoke generation to adjacent cells was observed in Comparative Example 1. In this way, it was confirmed that by using an elastic member having a predetermined resin composition, heat conduction between battery cells during heat generation can be suppressed.

[0059] In addition, in Examples 1 and 3, adjacent cells were deformed, but in Example 2, adjacent cells were not deformed. In Example 1, the size of the resin composition (X2 / X1, Y2 / Y1) was small, so the expansion stress was concentrated in a part of the adjacent cells, and in Example 3, the resin composition was arranged so as to penetrate the elastic member, so the expansion stress was concentrated in a part of the adjacent cells, which is presumably why adjacent cells were deformed. In contrast, in Example 2, the size of the resin composition (T2 / T1, X2 / X1, Y2 / Y1) was appropriate, so it is presumed why adjacent cells were not deformed. [Explanation of symbols]

[0060] 1 ... Battery cell 2. Elastic member 3. Resin composition 10 ... Battery module 11...Cathode active material layer 12...Negative electrode active material layer 13...electrolyte layer 14...Positive electrode current collector 15...Negative electrode current collector

Claims

1. A battery module having a plurality of battery cells arranged along a thickness direction, the battery module has an elastic member between adjacent battery cells, A resin composition having thermal expansion properties is disposed on the elastic member, the resin composition is disposed so as to include a center of the battery cell when viewed in a plan view along the thickness direction, The resin composition has an expansion initiation temperature of 80° C. or higher, The thermal conductivity of the resin composition after expansion is 0.5 W / m K or less, The resin composition contains a thermoplastic resin and a layered inorganic material that is an expandable material, the elastic member has a concave-convex pattern on only one surface in the thickness direction, the resin composition is disposed in a groove portion formed on the surface having the concave-convex pattern of the elastic member, When the thickness of the elastic member is T 1 and the thickness of the resin composition is T 2 , the ratio of T 2 to T 1 (T 2 / T 1 ) is 50% or more and 70% or less, a battery module in which, when viewed in a plane along the thickness direction, the elastic member has a rectangular shape, a direction parallel to a long side is a first direction, a direction perpendicular to the first direction is a second direction, a length of the elastic member in the first direction is X1, a length of the resin composition in the first direction is X2, a length of the elastic member in the second direction is Y1, and a length of the resin composition in the second direction is Y2, a ratio of X2 to X1 (X2 / X1) and a ratio of Y2 to Y1 (Y2 / Y1) are 25% or more and 50% or less, respectively.

2. The X ２ / X １ and the Y ２ / Y １ and are each 30% or more.

3. When viewed in a plane along the thickness direction, the area of ​​a region defined by the outer edge of the elastic member is defined as S １ The area of ​​the region defined by the outer edge of the resin composition is S ２ In this case, the S １ The above S ２ The ratio of (S ２ / S １ 2. The battery module according to claim 1, wherein the ratio of the resistance to the capacitance of the battery cell to the capacitance of the substrate is 6.25% or more and 25% or less.

4. The battery module according to claim 1 , wherein the concave-convex pattern is a comb-like, stripe-like, or dot-like pattern.

5. The thermoplastic resin is polypropylene, The battery module according to claim 1 , wherein the layered inorganic material is thermally expandable graphite.

6. A battery module as described in claim 1, wherein the resin composition has an uneven pattern on the surface side having the uneven pattern of the elastic member.

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