battery cell

Abstract

To suppress damage to the electrode body when it undergoes thermal expansion. [Solution] A battery cell comprising an electrode body, a metal case housing the electrode body, and a resin thermal conductive sheet provided inside the case between the electrode body and the case, in contact with the electrode body and the case, characterized in that the Young's modulus of the thermal conductive sheet is smaller than the Young's modulus of the electrode body.

Description

Technical Field

[0001] The present invention relates to a battery cell.

Background Art

[0002] Patent Document 1 discloses a all-solid-state battery cell in which an electrode laminate is enclosed inside a case, and includes a heat transfer material provided inside the case and contacting the bottom surface of the case and the electrode body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1, when the electrode body thermally expands, a load that compresses the heat transfer material from the electrode body to the case side acts on the heat transfer material. Therefore, if the reaction force from the heat transfer material is large, damage will occur to the electrode body.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery cell capable of suppressing damage to the electrode body when the electrode body thermally expands.

Means for Solving the Problems

[0006] The present invention is a battery cell including an electrode body, a metal case that houses the electrode body, and a resin-made heat conduction sheet provided between the electrode body and the case inside the case and contacting the electrode body and the case, wherein the Young's modulus of the heat conduction sheet is smaller than the Young's modulus of the electrode body.

Effects of the Invention

[0007] In this invention, damage to the electrode body can be suppressed when the electrode body undergoes thermal expansion. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing a battery cell in an embodiment. [Figure 2] This is a diagram illustrating the internal structure of a battery cell. [Figure 3] This is a cross-sectional view showing the internal structure of a battery cell. [Figure 4] This is a cross-sectional view showing the laminated structure of the case, thermal conductive sheet, and electrode body. [Modes for carrying out the invention]

[0009] The following describes the battery cells in embodiments of the present invention in detail. However, the present invention is not limited to the embodiments described below.

[0010] Figure 1 is a perspective view showing a battery cell in an embodiment. The battery cell 1 is a prismatic cell. The battery cell 1 comprises a case 2, an electrode body 3, a thermal conductive sheet 4, and terminals 5 and 6. As shown in Figure 2, the electrode body 3, the thermal conductive sheet 4, and the electrolyte are housed inside the case 2.

[0011] Case 2 is a metal case that houses the electrode body 3. Case 2 constitutes a metal layer. Case 2 is a rectangular can formed in a roughly rectangular parallelepiped shape. For example, Case 2 is made of aluminum or an aluminum alloy. Case 2 has a case body 11 and a lid 12. The case body 11 is a housing with an opening at the top. The lid 12 is joined to the case body 11 so as to close the opening of the case body 11. The case body 11 and the lid 12 are joined by welding. The inside of Case 2 is sealed. Inside Case 2 are the electrode body 3, a heat conductive sheet 4, and an electrolyte.

[0012] The electrode body 3 is a wound body with its upper edge 3a and lower edge 3b sealed in the height direction of the battery cell 1. The electrode body 3 constitutes the electrode layer. In the electrode body 3, one end 3c in the width direction of the battery cell 1 is a positive electrode connection portion where only the portion where the positive electrode current collector is exposed is wound, and the other end 3d is a negative electrode connection portion where only the portion where the negative electrode current collector is exposed is wound. Terminal 5, which is the external terminal on the positive electrode side, is electrically connected to the positive electrode connection portion. Terminal 6, which is the external terminal on the negative electrode side, is electrically connected to the negative electrode connection portion. Both ends 3c and 3d are open in the width direction of the battery cell 1. When the electrode body 3 is viewed from the thickness direction of the battery cell 1, two sides including the upper edge 3a and the lower edge 3b form a closed section, and two sides including ends 3c and 3d form an open section. The battery cell 1 has closed sections in the electrode layer on at least two of its four sides. On the other hand, in the open sections, the electrolyte can move between the inside and outside of the electrode body 3 via ends 3c and 3d. The electrolyte is present both inside the electrode body 3 and outside the electrode body 3 as excess liquid. Most of the electrolyte permeates into the inside of the electrode body 3. The excess liquid that does not permeate into the inside of the electrode body 3 accumulates at the bottom 13 of the case 2. When the battery cell 1 undergoes repeated charging and discharging, the electrode body 3 expands and contracts due to the charging and discharging.

[0013] For example, electrode body 3 comprises a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, and a strip-shaped separator. Electrode body 3 has a laminate formed by stacking the positive electrode sheet, the negative electrode sheet, and the separator. Electrode body 3 is a wound body. Electrode body 3 is a flat electrode body formed by winding a laminate in which the positive electrode sheet and the negative electrode sheet are stacked with a separator in between. Before winding, the laminate is stacked in the thickness direction in the order of positive electrode sheet, separator, negative electrode sheet, and separator. In electrode body 3, the positive electrode sheet, the negative electrode sheet, and the separator are stacked so that their respective longitudinal directions coincide. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is a long positive electrode substrate. The positive electrode active material layer is provided on the positive electrode current collector. The positive electrode current collector includes an uncoated positive electrode side at one end in the width direction where the positive electrode active material layer is not formed and the positive electrode current collector is exposed. The unpainted portion on the positive electrode side constitutes the positive electrode current collector when the positive electrode sheet is wound around it. A positive electrode current collector terminal is connected to the positive electrode current collector. The positive electrode current collector terminal is connected to terminal 5, which is an external terminal on the positive electrode side. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector is a long negative electrode substrate. The negative electrode active material layer is provided on the negative electrode current collector. The negative electrode current collector includes an unpainted portion on the negative electrode side at the other end in the width direction where the negative electrode active material layer is not formed and the negative electrode current collector is exposed. The unpainted portion on the negative electrode side constitutes the negative electrode current collector when the negative electrode sheet is wound around it. A negative electrode current collector terminal is connected to the negative electrode current collector. The negative electrode current collector terminal is connected to terminal 6, which is an external terminal on the negative electrode side.

[0014] The thermal conductive sheet 4 is positioned between the case 2 and the electrode body 3. The thermal conductive sheet 4 is positioned in the closed section of the electrode body 3. In the battery cell 1, a heat transfer layer is positioned between the closed section and the metal layer. The thermal conductive sheet 4 is an insulating material, and is made of, for example, resin. The thermal conductive sheet 4 constitutes the heat transfer layer.

[0015] As shown in Figure 3, the thermal conductive sheet 4 includes a first thermal conductive sheet 21 that is in contact with the upper edge 3a of the electrode body 3 and a second thermal conductive sheet 22 that is in contact with the lower edge 3b of the electrode body 3.

[0016] The first thermal conductive sheet 21 is provided between the electrode body 3 and the cover body 12. In the width and thickness directions of the battery cell 1, the first thermal conductive sheet 21 is a flat sheet that is in overall contact with the upper edge 3a of the electrode body 3 and the inner surface of the cover body 12. As shown in Figure 4, a laminated structure is formed in which the cover body 12, the first thermal conductive sheet 21, and the electrode body 3 are stacked.

[0017] The second thermal conductive sheet 22 is provided between the electrode body 3 and the bottom 13 of the case body 11. In the width and thickness directions of the battery cell 1, the second thermal conductive sheet 22 is a flat sheet that is in overall contact with the lower edge 3b of the electrode body 3 and the inner surface of the bottom 13 of the case body 11. A laminated structure is formed in which the bottom 13 of the case body 11, the second thermal conductive sheet 22, and the electrode body 3 are stacked. A cooler is attached to the outer surface of the bottom 13 of the case 2. The cooler cools the electrode body 3 and is provided on the outside of the case 2. In the battery cell 1 with this cooler attached, there is a cooling structure that cools the electrode body 3 from the bottom 13 side of the case 2 via the second thermal conductive sheet 22.

[0018] The thermal conductive sheet 4 has a Young's modulus smaller than that of the electrode body 3.

[0019] If the Young's moduli of the thermal conductive sheet 4 and the electrode body 3 were the same, the reaction force from the thermal conductive sheet 4 would be large when the thermal conductive sheet 4 is compressed, causing damage to the electrode body 3. To avoid this, the battery cell 1 is configured such that the Young's moduli of the thermal conductive sheet 4 are smaller than those of the electrode body 3. For example, it is preferable that the Young's moduli of the thermal conductive sheet 4 be 1 / 100th or less of that of the electrode body 3. As the shear force of the thermal conductive sheet 4 decreases during deformation when case 2 expands, the reaction force from the thermal conductive sheet 4 to the expansion of the electrode body 3 decreases, thereby reducing damage from the thermal conductive sheet 4 to the electrode body 3.

[0020] The battery cell 1 has a film structure for insulation inside the case 2. An insulating film is accommodated inside the case 2. The insulating film constitutes an insulating layer. The insulating film is provided between the inner surface of the side wall portion 14 of the case body 11 and the open section of the electrode body 3. On one side in the width direction of the battery cell 1, an insulating film is disposed between the end portion 3c of the electrode body 3 and the inner surface of the side wall portion 14. On the other side in the width direction of the battery cell 1, an insulating film is disposed between the end portion 3d of the electrode body 3 and the inner surface of the side wall portion 14. The insulating film provided between the inner surface of the side wall portion 14 of the case body 11 and the side surface of the electrode body 3 may be formed to entirely cover the inner surface of the side wall portion 14, or may be formed to entirely cover the side surface of the electrode body 3.

[0021] As described above, according to the embodiment, the shearing force of the heat conduction sheet 4 when the electrode body 3 expands is reduced, and the occurrence of damage from the heat conduction sheet 4 to the electrode body 3 can be suppressed.

[0022] Note that the heat conduction sheet 4 can be designed to define the size of the heat conduction resin before manufacturing the battery cell 1 and to have the target thickness and width after manufacturing.

Explanation of Reference Numerals

[0023] 1 Battery cell 2 Case 3 Electrode body 4 Heat conduction sheet

Claims

1. Electrode body and A metal case for housing the electrode body, A resin thermal conductive sheet is provided inside the case between the electrode body and the case, and is in contact with the electrode body and the case. A battery cell equipped with, The Young's modulus of the thermal conductive sheet is smaller than that of the electrode body. A battery cell characterized by the following features.

2. The Young's modulus of the thermal conductive sheet is 1 / 100th or less of the Young's modulus of the electrode body. The battery cell according to feature 1.

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