Secondary batteries

Abstract

During charging, the temperature difference between the external terminals and their surroundings and the electrode body inside the cell case is suppressed. [Solution] The secondary battery comprises one or more battery cells. Each of the one or more battery cells includes a cell case, a plurality of electrode bodies, a current collector terminal, an external terminal, and a thermal conductive member. The plurality of electrode bodies are housed in the cell case. The current collector terminal is housed in the cell case and is electrically connected to the plurality of electrode bodies. The external terminal is electrically connected to the current collector terminal and protrudes to the outside of the cell case through a first wall of the cell case. The thermal conductive member is interposed between adjacent electrode bodies among the plurality of electrode bodies and is arranged to be in contact with each of the adjacent electrode bodies and the current collector terminal.

Description

Technical Field

[0001] This disclosure relates to secondary batteries.

Background Art

[0002] Patent Document 1 discloses a battery module. This battery module includes a plurality of battery cells each having a bottom surface and arranged in a first direction, a cooling plate facing the bottom surfaces of the plurality of battery cells, and a heat conductive member provided between the battery cells and the cooling plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During charging of the battery cell, the temperature of the external terminal of the battery cell rises due to Joule heat generation. As a result, the temperature difference between the external terminal and its periphery (the wall of the cell case) and the electrode body inside the cell case tends to increase. In a secondary battery, it is desirable to suppress such a temperature difference.

Means for Solving the Problems

[0005] The secondary battery according to this disclosure includes one or more battery cells. Each of the one or more battery cells includes a cell case, a plurality of electrode bodies, a current collecting terminal, an external terminal, and a heat conductive member. The plurality of electrode bodies are housed in the cell case. The current collecting terminal is housed in the cell case and is electrically connected to the plurality of electrode bodies. The external terminal is electrically connected to the current collecting terminal and protrudes outside the cell case through the first wall of the cell case. The heat conductive member is interposed between adjacent electrode bodies among the plurality of electrode bodies and is arranged to contact each of the adjacent electrode bodies and the current collecting terminal.

Effects of the Invention

[0006] According to this disclosure, heat generated at the external terminal during charging is more easily transferred to the multiple electrode bodies via the current collector terminal and thermal conductive member. Therefore, the temperature difference between the external terminal and its surroundings and the multiple electrode bodies can be suppressed during charging. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view showing the schematic configuration of a battery cell included in a secondary battery according to an embodiment. [Figure 2] This figure shows the internal structure of a battery cell as viewed from the Y direction in Figure 1. [Figure 3] This figure shows the internal structure of a battery cell related to a comparative example. [Figure 4] This is a diagram illustrating the effects of a secondary battery according to an embodiment. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described with reference to the attached drawings. Common elements in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

[0009] 1. Configuration of a secondary battery Figure 1 is a perspective view showing the schematic configuration of a battery cell 10 included in a secondary battery 1 according to this embodiment. The secondary battery 1 (see Figure 2) includes one or more battery cells 10. The secondary battery 1 may also include a battery module containing a plurality of battery cells 10. The secondary battery 1 is mounted on a vehicle, for example, and supplies power to the vehicle. The battery cell 10 is, as an example, a lithium-ion battery.

[0010] The battery cell 10 includes a cell case 12, a plurality of electrode bodies 14, a pair of current collection terminals (positive electrode current collection terminal and negative electrode current collection terminal) 16, and a pair of external terminals (positive electrode external terminal and negative electrode external terminal) 18. The cell case 12 has, for example, a rectangular parallelepiped shape. The cell case 12 is formed from a metal material such as aluminum. In Figure 1, the Z direction is the height direction of the battery cell 10. The X direction is the direction of the short side of the cell case 12 perpendicular to the Z direction. The Y direction is the direction of the long side of the cell case 12 perpendicular to the Z direction.

[0011] The cell case 12 houses a plurality (for example, four) of electrode bodies 14. Each electrode body 14 is formed in a plate shape. As shown in Figure 1, the plurality of electrode bodies 14 are arranged side by side, for example, with the X direction as its thickness direction. The electrode body 14 includes a positive electrode and a negative electrode and is formed to hold an electrolyte between the positive electrode and the negative electrode. The electrode body 14 may be of a stacked type or a wound type.

[0012] Figure 2 shows the internal structure of the battery cell 10 as viewed from the Y direction in Figure 1, and more specifically, it shows the internal structure of the battery cell 10 at the location of one external terminal (e.g., positive terminal) 18. The internal structure of the battery cell 10 at the location of the other external terminal (e.g., negative terminal) 18 is the same as that shown in Figure 2.

[0013] The cell case 12 houses a pair of current collection terminals 16. Each electrode body 14 is electrically connected to a pair of current collection terminals 16 corresponding to each of the pair of electrode tabs 22 via a pair of electrode tabs 22 22. The upper wall (first wall) of the cell case 12, located on the upper side in the Z direction (height direction), is formed as, for example, a lid 20. The external terminals 18 are attached to the lid 20 in an electrically insulated manner. The external terminals 18 are electrically connected to each current collection terminal 16 inside the cell case 12 and protrude to the outside of the cell case 12 through the lid 20.

[0014] The secondary battery 1 may include a temperature control device 24. The temperature control device 24 is positioned, for example, to be in contact with the bottom wall 26 (second wall) of the cell case 12 located on the opposite side of the lid 20 (first wall). The temperature control device 24 functions as a heater / cooler that heats and cools each electrode body 14 via the bottom wall 26. A thermally conductive material may be interposed between the bottom wall 26 and the temperature control device 24. The temperature control device 24 may also be configured to function as either a heater or a cooler, or only one of them.

[0015] During battery cell charging (especially during rapid charging with high current), Joule heating causes the temperature of the battery cell's external terminals to rise. As a result, the temperature difference ΔT between the external terminals and their surroundings (the cell case wall (e.g., lid)) and the electrode body inside the cell case tends to increase. Furthermore, in secondary batteries installed in vehicles, this temperature difference ΔT can have the following effects. Specifically, in vehicles capable of external charging of their installed secondary batteries (e.g., battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs)), there has been a growing demand for shorter charging times in recent years. The charging current during rapid charging is determined, for example, based on the temperature of the battery cell's electrode body for safety protection. Also, if the electrode body temperature is low during rapid charging, measures such as using a device like the temperature control device 24 described above to raise the temperature of the electrode body from the outside may be taken, but it is difficult to effectively heat the electrode body due to its thermal resistance. Moreover, as mentioned above, when the temperature of the external terminals rises due to Joule heating, heat is more easily transferred from the external terminals to the wall (e.g., lid) which has lower thermal resistance. As a result, the temperature at the location of the battery temperature sensor mounted on the wall may rise, triggering a protection function that suppresses the charging current. This can be detrimental to shortening the charging time.

[0016] In secondary batteries, it is desirable to suppress the above-mentioned temperature difference ΔT. Therefore, the battery cell 10 included in the secondary battery 1 according to this embodiment further includes a thermally conductive member 28.

[0017] As shown in FIG. 2, the heat conductive member 28 is interposed between adjacent electrode bodies 14. More specifically, in the example of the battery cell 10 shown in FIG. 2, there are three sets of adjacent electrode bodies 14. The heat conductive member 28 is, for example, interposed between the adjacent electrode bodies 14 in each of the three sets. And the heat conductive member 28 is arranged so as to contact each of the adjacent electrode bodies 14 and the current collecting terminal 16 in each set. More specifically, each heat conductive member 28 is arranged so as to contact each of the pair of current collecting terminals 16. The contact between the pair of current collecting terminals 16 and each heat conductive member 28 is performed by bonding such as adhesion.

[0018] Also, in the present embodiment, each heat conductive member 28 is arranged so as to contact the inner wall surface 30 (the inner bottom surface of the cell case 12) of the bottom wall 26 (the second wall) of the cell case 12. The contact between the bottom wall 26 and each heat conductive member 28 is also performed by bonding such as adhesion. As a result, each heat conductive member 28 connects from the pair of current collecting terminals 16 to the bottom wall 26 in the Z direction while contacting each of the adjacent electrode bodies 14.

[0019] The heat conductive member 28 is, for example, formed in a sheet shape. And in the Z direction, one end of the heat conductive member 28 formed in a sheet shape contacts each of the pair of current collecting terminals 16, and the other end of the heat conductive member 28 located on the opposite side of the one end contacts the bottom wall 26. Also, when the battery cell 10 is viewed from the X direction in FIG. 1, the heat conductive member 28 is, for example, arranged so as to entirely cover the surfaces of the electrode bodies 14 that face each other in the adjacent electrode bodies 14.

[0020] The heat conductive member 28 is formed of a material having non - conductivity and a high heat conductivity. More specifically, the heat conductive member 28 has, for example, a higher heat conductivity than the electrode body 14. As an example, the material is a fine ceramic such as aluminum nitride or silicon carbide.

[0021] 2. Effects FIG. 3 is a diagram showing the internal structure of the battery cell 100 according to the comparative example. Different from the battery cell 10 according to the present embodiment, the battery cell 100 according to the comparative example does not include the heat conductive member 28. That is, in the battery cell 100, there are few heat transfer paths from the external terminal 18 to each electrode body 14. For this reason, as described above as a problem, the heat generated at the external terminal 18 during charging is likely to escape to the lid 20 side (see arrow AR1 in FIG. 4). As a result, as shown in FIG. 3, the temperature difference ΔT between the external terminal 18 and its periphery (lid 20) and each electrode body 14 inside the cell case 12 becomes large.

[0022] FIG. 4 is a diagram for explaining the effect of the secondary battery 1 according to the present embodiment. The battery cell 10 according to the present embodiment includes the heat conductive member 28. As described above, the heat conductive member 28 is interposed between adjacent electrode bodies 14 and is arranged to contact each of the adjacent electrode bodies 14 and each of the pair of current collecting terminals. Thereby, as represented by arrows AR2 and AR3 in FIG. 4, the heat conductive member 28 serves as a heat transfer path, and it is possible to effectively promote transporting the heat generated at each external terminal 18 during charging to each part of each electrode body 14. As a result, as shown in FIG. 5, the temperature of each external terminal 18 and its periphery (lid 20) decreases as compared with the comparative example. On the other hand, due to the heat reception from the side of each external terminal 18, the temperature of each electrode body 14 rises, and the variation in the temperature of each part of each electrode body 14 is suppressed. Thus, according to the battery cell 10 provided with the heat conductive member 28, during charging, the heat generation of the external terminal 18 can be effectively utilized to effectively suppress the temperature difference ΔT. And the suppression of the temperature difference ΔT leads to shortening of the charging time (improvement of charging efficiency) due to the improvement of the average current value during charging.

[0023] Broadly speaking, the "thermal conductive member according to this disclosure" only needs to be positioned so as to contact at least the current collector terminal 16, or the bottom wall 26 (inner wall surface 30) of the cell case 12. Furthermore, the thermal conductive member 28 according to this embodiment is in contact with both the current collector terminal 16 and the bottom wall 26. That is, the thermal conductive member 28 connects the current collector terminal 16 to the bottom wall 26 while in contact with each of the adjacent electrode bodies 14. As a result, as shown by arrow AR4 in Figure 4, it is possible to use the heat from the temperature control device 24 to heat each part of each electrode body 14 evenly. In other words, the heating efficiency of each electrode body 14 by the temperature control device 24 is improved. This also leads to an improvement in charging efficiency. In addition, by having the thermal conductive member 28, the cooling efficiency of the electrode body 14 by the temperature control device 24 is also improved when the temperature of the electrode body 14 rises, regardless of charging. [Explanation of Symbols]

[0024] 1 secondary battery, 10 battery cells, 12 cell case, 14 electrode body, 16 current collector terminal, 18 external terminal, 20 cell case lid, 22 electrode tabs, 24 temperature control device, 26 cell case bottom wall, 28 thermal conductive material, 30 inner wall surface of bottom wall

Claims

1. A secondary battery comprising one or more battery cells, Each of the one or more battery cells is Cell case and, Multiple electrode bodies housed in the aforementioned cell case, A current collector terminal housed in the cell case and electrically connected to the plurality of electrode bodies, An external terminal is electrically connected to the current collection terminal and protrudes to the outside of the cell case by penetrating the first wall of the cell case, A thermal conductive member is interposed between adjacent electrode bodies among the plurality of electrode bodies and is arranged to contact each of the adjacent electrode bodies with the current collection terminal, including Secondary battery.

2. A secondary battery according to claim 1, The device further includes a temperature control device that performs at least one of heating and cooling of the plurality of electrode bodies via a second wall of the cell case located on the opposite side of the first wall, The heat-conducting member is positioned to be in contact with the second wall. Secondary battery.

3. A secondary battery according to claim 1 or 2, The aforementioned heat-conducting member is formed in a sheet shape. Secondary battery.

4. A secondary battery according to claim 1 or 2, The thermal conductive member has a higher thermal conductivity than the plurality of electrode bodies. Secondary battery.

5. A secondary battery according to claim 4, The aforementioned heat-conducting member is a fine ceramic. Secondary battery.

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