Secondary battery cell

Abstract

The present invention provides a secondary battery cell that facilitates the supply of an appropriate amount of additive into the cell case depending on the use of the secondary battery cell. [Solution] The secondary battery cell comprises a cell case, an electrode body, an electrolyte, and a bag. The electrode body is housed in the cell case. The electrolyte is sealed in the cell case. The bag is positioned between the side wall of the cell case facing the electrode body and the electrode body, and contains a liquid including additives for the electrolyte. The bag has a convex shape that protrudes toward the electrode body and has an opening that faces vertically upward.

Description

Technical Field

[0001] This disclosure relates to a secondary battery cell.

Background Art

[0002] Patent Document 1 discloses a non-aqueous electrolyte secondary battery. This non-aqueous electrolyte secondary battery includes a fluoroethylene carbonate supply mechanism that supplies fluoroethylene carbonate to the non-aqueous electrolyte when the internal pressure of the battery case rises.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The additives contained in the electrolyte are consumed as the secondary battery is used. Therefore, according to the secondary battery described in Patent Document 1, the additives may decrease before the internal pressure of the battery case rises, and the performance of the secondary battery may deteriorate.

[0005] This disclosure has been made in view of the above problems, and an object thereof is to provide a secondary battery cell that can easily supply an appropriate amount of additives into the cell case according to the use of the secondary battery cell.

Means for Solving the Problems

[0006] The secondary battery cell according to this disclosure includes a cell case, an electrode body, an electrolyte, and a bag body. The electrode body is housed in the cell case. The electrolyte is enclosed in the cell case. The bag body is disposed between the side wall of the cell case facing the electrode body and the electrode body, and houses a liquid containing additives of the electrolyte. And the bag body has a convex shape protruding toward the electrode body and has an opening facing upward in the vertical direction. [Effects of the Invention]

[0007] According to this disclosure, since the additive is supplied as the electrode body expands, it is possible to easily supply an appropriate amount of the additive into the cell case according to the usage of the secondary battery cell. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the schematic configuration of a secondary battery cell according to an embodiment. [Figure 2] This is a diagram illustrating the effects of a secondary battery cell according to an embodiment. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the attached drawings.

[0010] 1. Configuration of a secondary battery cell Figure 1 is a diagram showing the schematic configuration of a secondary battery cell (hereinafter simply referred to as a battery cell) 10 according to this embodiment. In Figure 1, the Z direction is the height direction of the battery cell 10 and is parallel to the vertical direction. The X direction is the direction of the shorter side of the cell case 12, which is perpendicular to the Z direction. The Y direction is the direction of the longer side of the cell case 12, which is perpendicular to the Z direction. The X and Y directions are parallel to the horizontal direction. More specifically, Figure 1(A) is a perspective view of the battery cell 10, and Figure 1(B) is a view of the internal structure of the battery cell 10 from the Y direction.

[0011] The battery cell 10 is installed in a vehicle, for example, as a battery module containing multiple battery cells 10, and supplies power to the vehicle. The battery cell 10 is, as an example, a lithium-ion battery. The battery cell 10 includes a cell case 12, an electrode body 14, a pair of external terminals (positive electrode external terminal and negative electrode external terminal) 16, and an electrolyte (non-aqueous electrolyte) 18.

[0012] The cell case 12 is, for example, a rectangular cell case having a rectangular parallelepiped shape. That is, the battery cell 10 is, for example, a rectangular cell. The cell case 12 is formed from a metal material such as aluminum.

[0013] The cell case 12 houses, for example, one electrode body 14. The electrode body 14 is formed, for example, in a plate shape. As shown in Figure 1, the electrode body 14 is arranged, 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 18 between the positive electrode and the negative electrode. The electrode body 14 is, for example, a wound electrode body, but it may also be a laminated electrode body. Note that two or more electrode bodies 14 may be arranged side by side in the cell case 12, for example, with the X direction as its thickness direction.

[0014] A pair of external terminals 16 are electrically connected to the electrode body 14 via electrode tabs and current collector terminals, which are not shown in the figure.

[0015] Furthermore, the cell case 12 is sealed with an electrolyte 18. The electrolyte 18 contains additive A. Additive A is exemplified as follows, depending on the configuration of the negative electrode of the electrode body 14. Specifically, in the case of a negative electrode containing silicon dioxide, fluoroethylene carbonate (FEC) is exemplified as additive A. In the case of a negative electrode containing graphite, vinylene carbonate (VC), lithium bisoxalate borate (LiBOB), etc., are exemplified as additive A.

[0016] Additive A contained in the electrolyte 18 is consumed as the battery cell 10 is used. If the amount of additive A decreases as a result of consumption, the performance of the battery cell 10 may deteriorate, and if additive A is completely depleted, the performance of the battery cell 10 will rapidly decline. On the other hand, if the electrolyte 18 contains too much additive A, a film is more likely to form on the surface of the electrode body 14, increasing the internal resistance of the battery cell 10. For this reason, simply including a large amount of additive A in the electrolyte 18 beforehand is not appropriate in order to suppress the deterioration of the performance of the battery cell 10.

[0017] Therefore, the battery cell 10 according to this embodiment includes a bag 20 that contains a liquid containing additive A of the electrolyte 18. The "liquid" here is, for example, the same electrolyte as the electrolyte 18, but is not necessarily limited to the same electrolyte as the electrolyte 18. The bag 20 is formed of, for example, a resin material that has electrolyte resistance (e.g., polypropylene).

[0018] The bag 20 is positioned between the side wall of the cell case 12 facing the electrode body 14 and the electrode body 14. In the example shown in Figure 1(B), the side walls are the two side walls 12a and 12b, which face the two sides 14a and 14b of the electrode body 14, respectively. Each of the sides 14a and 14b is a side of the electrode body 14 perpendicular to the thickness direction (=X direction) of the electrode body 14. That is, in the example shown in Figure 1(B), the bag 20 is interposed between the electrode body 14 and the cell case 12 on each side in the X direction. The bag 20 is attached, for example, to the side walls 12a and 12b.

[0019] Each bag 20 has a convex shape 20a that protrudes toward the electrode body 14. More specifically, when viewed from the Y direction (see Figure 1(B)), the convex shape 20a is a curved convex shape that protrudes in a curved manner toward the electrode body 14 from the side wall 12a or 12b. As shown in Figure 1(B), each bag 20 has an opening 20b that faces upward in the vertical direction (Z direction). More specifically, the opening 20b is provided, for example, at the top of each bag 20 in the vertical direction (the base end on the upper side of the convex shape 20a). Inside each bag 20, the liquid containing additive A is filled, for example, up to the vicinity of the opening 20b.

[0020] Furthermore, although not shown in the illustration here, when each bag 20 is viewed from the Z direction, just as when each bag 20 is viewed from the Y direction, each bag 20 may have a convex curved shape that curves outward from the side wall 12a or 12b toward the electrode body 14. In addition, with respect to the Y direction, the opening 20b may be provided, for example, in the center of the cell case 12 in the Y direction.

[0021] Also, unlike the example shown in FIG. 1(B), the bag body 20 may be disposed only between either one of the side walls 12a and 12b of the cell and the electrode body 14. Further, in an example in which a plurality of electrode bodies 14 are provided in the cell case 12, the bag body 20 may be disposed as follows. That is, the bag body 20 may be disposed between the electrode body 14 located at at least one end of the plurality of electrode bodies 14 arranged side by side in the horizontal direction (for example, the X direction) and the side walls 12a and 12b of the cell case 12 facing the electrode body 14.

[0022] 2. Effects FIG. 2 is a diagram for explaining the effects of the secondary battery cell 10 according to the present embodiment. When the battery cell 10 deteriorates due to use, the electrode body 14 may expand as shown in the upper part of FIG. 2. More specifically, during expansion, the electrode body 14 increases in thickness (length in the X direction) in such a manner that the center of the electrode body 14 in the Z direction (height direction of the battery cell 10) bulges most as shown in FIG. 2.

[0023] As described above, in the battery cell 10 according to the present embodiment, the bag body 20 containing the liquid containing additive A (for example, the electrolyte containing additive A) is disposed between each of the side walls 12a and 12b of the cell case 12 and the electrode body 14. The bag body 20 has a convex shape (more specifically, a convex curve shape) 20a protruding toward the electrode body 14 and an opening 20b facing upward in the vertical direction. As a result, as shown in the lower part of FIG. 2, as the electrode body 14 expands, the bag body 20 is pushed by the electrode body 14, and thus additive A (more specifically, for example, the electrolyte containing additive A) is discharged from the opening 20b (that is, supplied into the cell case 12). As a result, the liquid level height of the electrolyte 18 in the cell case 12 is restored. When the degree of expansion (increase in thickness) of the electrode body 14 becomes large, the discharge amount (supply amount) of additive A increases.

[0024] As described above, according to the battery cell 10 of this embodiment, additive A is supplied as the electrode body 14 expands. Therefore, it is possible to easily supply an appropriate amount of additive A into the cell case 12 according to the usage of the battery cell 10. This contributes to extending the lifespan of the battery cell 10. In addition, according to the battery cell 10 of this embodiment, it is possible to realize an additive A supply mechanism using the electrode body 14 and the bag body 20 that utilizes the expansion of the electrode body 14.

[0025] Furthermore, according to the battery cell 10 of this embodiment, unlike the technology described in Patent Document 1, additive A can be added (supplied) even if the internal pressure of the cell case 12 does not rise. Therefore, a supply mechanism for additive A can be realized without the need for sensors such as an internal pressure sensor and a control unit. [Explanation of symbols]

[0026] 10 Secondary battery cell, 12 Cell case, 12a, 12bb Side wall of cell case, 14 Electrode body, 16 External terminal, 18 Electrolyte, 20 Bag, 20a Convex shape of bag, 20b Opening of bag

Claims

[Claim 1] Cell case and, The electrode body housed in the cell case, The electrolyte sealed in the aforementioned cell case, A bag containing a liquid including an additive for the electrolyte, is disposed between the side wall of the cell case facing the electrode body and the electrode body. Equipped with, The bag has a convex shape that protrudes toward the electrode body and has an opening that faces vertically upward. Secondary battery cell.

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