JP7501068B2 - In-vehicle secondary battery device - Google Patents

Description

The present invention relates to a secondary battery device mounted on a vehicle.

Conventionally, vehicles are equipped with secondary battery devices to supply power to various electrical devices. Also, as disclosed in the following Patent Document 1, a secondary battery device in which an electrode body and an electrolyte are housed in a specified case (a battery can in Patent Document 1), is known in which the case is provided with an open valve, and when the internal pressure of the case exceeds a specified value, the open valve is opened (cracked) to release gas inside the case to the outside of the case.

JP 2016-100273 A

In a secondary battery device equipped with a safety valve as described above, it is possible to prevent the internal pressure of the case from becoming excessively high. However, when this secondary battery device is mounted on a vehicle, if it is simply mounted in an engine room or the like where various devices that tend to become hot are arranged, there is a risk that the gasified electrolyte that leaks to the outside of the case through the safety valve will come into contact with the high-temperature devices and further increase in temperature.

The present invention was made in consideration of the above circumstances, and aims to provide an in-vehicle secondary battery device that can ensure high safety.

In order to solve the above problem, the present invention provides a secondary battery device mounted on a vehicle, comprising: a battery cell having a cell case that contains an electrode body and an electrolyte inside, a pair of terminals, and an open valve provided at the bottom of the cell case that opens to communicate between the inside and the outside of the cell case when the pressure inside the cell case reaches or exceeds a predetermined value; a storage container that contains the battery cell inside; and a liquid-absorbing material that is disposed between the bottom of the cell case and the opposite bottom of the storage container and is capable of absorbing the electrolyte , the open valve being provided on the bottom of the cell case, and the liquid-absorbing material being provided in a position that does not overlap with the open valve when viewed from above the vehicle (claim 1).

According to the present invention, an open valve is provided at the bottom of the cell case. Therefore, the liquid electrolyte that has accumulated at the bottom of the cell case, rather than the gasified electrolyte that has accumulated at the top of the cell case, is allowed to flow out of the cell case through the open valve, thereby reducing the pressure inside the cell case. This makes it possible to prevent the internal pressure of the cell case from becoming excessively high, while suppressing leakage of the gasified electrolyte to the outside of the cell case and the storage container. Therefore, even if the vehicle-mounted secondary battery device is mounted in an engine room or the like, contact between the gasified electrolyte and high-temperature devices can be prevented, ensuring high safety.

In addition, in the present invention, a liquid-absorbing material is provided between the lower surface of the cell case and the bottom surface of the storage container, so that the electrolyte that has flowed out of the cell case through the release valve can be absorbed by the liquid-absorbing material. This makes it possible to prevent the electrolyte that has flowed out of the cell case from leaking out of the storage container, thereby reliably improving safety.

Furthermore, according to the present invention , since the release valve is provided on the underside of the cell case, it is possible to more reliably prevent the gasified electrolyte from leaking out of the cell case through the release valve. Moreover, since the release valve and the liquid-absorbing material do not overlap when viewed from above the vehicle, it is possible to prevent the release valve from being blocked by the liquid-absorbing material whose absorbing power has decreased due to deterioration, etc., and it is possible to more reliably and quickly allow the electrolyte to leak out of the cell case.

In the above configuration, preferably, the battery cells are provided in a row along the bottom surface of the storage container, and when the direction in which the battery cells are arranged is the fore-aft direction and the direction perpendicular to the fore-aft direction when viewed from above the vehicle is the left-right direction, the battery cells include a front battery cell and a rear battery cell adjacent in the fore-aft direction, and the release valve of the front battery cell is provided in a position shifted to one side in the left-right direction with respect to a reference line extending in the fore-aft direction, and the release valve of the rear battery cell is provided in a position shifted to the other side in the left-right direction with respect to the reference line (Claim 2 ).

In this configuration, the open valves of two adjacent battery cells are arranged at different positions in the left-right direction across the reference line, and the distance between the open valves is longer than when these open valves are arranged in a row in the front-to-rear direction. This prevents electrolyte that flows out of one open valve of two adjacent battery cells from flowing into the vicinity of the other open valve and impeding the outflow of electrolyte from the other open valve. This allows electrolyte to flow smoothly from each open valve, allowing the internal pressure of each cell case to be reduced early.

In the above configuration, preferably, the pair of terminals are a positive terminal and a negative terminal arranged to be spaced apart from each other across a center line that divides the cell case in the left-right direction, the release valve is provided at a position biased toward either the positive terminal or the negative terminal from the center line on the underside of the cell case, and the front battery cell and the rear battery cell are arranged so that the center lines of both battery cells coincide with the reference line and the positive terminal of one battery cell and the negative terminal of the other battery cell are aligned in a straight line in the front-to-rear direction (claim 3 ).

With this configuration, it is possible to realize the above-mentioned configuration, i.e., a configuration in which the release valves of adjacent battery cells are located at different positions in the left-right direction across the reference line, using battery cells with the same structure. Therefore, there is no need to prepare multiple types of battery cells with different structures, which is advantageous in terms of cost.

In the above configuration, preferably, the liquid-absorbing material has a first liquid-absorbing member and a second liquid-absorbing member that face each other in the left-right direction across an area including the open valves of the front battery cell and the rear battery cell when viewed from above the vehicle, and a first partition wall is provided between the front battery cell and the bottom surface of the storage container, extending from the first liquid-absorbing member toward the second liquid-absorbing member, passing behind the open valve of the front battery cell when viewed from above the vehicle, and a second partition wall is provided between the rear battery cell and the bottom surface of the storage container, extending from the second liquid-absorbing member toward the first liquid-absorbing member, passing in front of the open valve of the rear battery cell when viewed from above the vehicle, and gaps are formed between the first partition wall and the second liquid-absorbing member, and between the second partition wall and the first liquid-absorbing member (Claim 4 ).

With this configuration, the first and second partition walls can prevent the electrolyte that has flowed out of the open valve of one of the adjacent front and rear battery cells from flowing toward the other battery cell, while allowing the electrolyte to be quickly absorbed by the left and right liquid absorbing members. This can reliably prevent the temperature and pressure of the other battery cell from increasing due to the high-temperature electrolyte that has flowed out.

As an alternative configuration to the above, the storage container may include a plurality of battery cells arranged in a row along the bottom surface thereof, and when the direction in which the plurality of battery cells are arranged is defined as the front-to-rear direction and the direction perpendicular to the front-to-rear direction when viewed from above the vehicle is defined as the left-to-right direction, the open valve of each battery cell is provided at the lower part of one of the left and right sides of the cell case, and a partition wall is provided on the inner surface of the storage container opposite the open valve of each battery cell, separating the open valve of one of two adjacent battery cells from the open valve of the other battery cell in the front-to-rear direction in a side view (Claim 5 ).

Even with this configuration, the partition wall prevents electrolyte that has flowed out of the open valve of one of two adjacent battery cells from flowing toward the other battery cell, preventing the other battery cells from being heated and pressurized by the high-temperature electrolyte that has flowed out. In addition, with this configuration, the open valves are provided on the left and right sides of the cell case, making it possible to reduce the amount of electrolyte that flows out of the cell case compared to when the open valves are provided on the underside of the cell case.

As explained above, the vehicle-mounted secondary battery device of the present invention can reliably improve safety when mounted on a vehicle.

1 is a diagram showing a schematic configuration of a vehicle equipped with a lithium battery according to an embodiment of the present invention; 1 is a schematic front view showing a lithium battery and its surroundings in an engine compartment according to an embodiment of the present invention. 1 is a schematic perspective view of a lithium battery according to an embodiment of the present invention; FIG. 1 is a schematic perspective view of a battery cell according to an embodiment of the present invention. FIG. 2 is a top view showing the inside of a case main body according to the first embodiment. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. 7 is a cross-sectional view taken along line VII-VII of FIG. 6. 4 is a schematic perspective view for explaining a structure near a bottom surface of a case main body according to the first embodiment. FIG. 1 is a schematic top view for explaining the operation of the lithium battery according to the first embodiment; FIG. 1 is a schematic top view for explaining the operation of the lithium battery according to the first embodiment; FIG. FIG. 11 is a top view showing the inside of a case main body according to a second embodiment. This is a cross-sectional view taken along line XII-XII in Figure 11. 13 is a cross-sectional view taken along line VIII-VIII in FIG. 12. FIG. 11 is a schematic perspective view for explaining a structure near the bottom surface of a case main body according to a second embodiment. 13 is a schematic top view for explaining the operation of the lithium battery according to the second embodiment. FIG.

(General configuration of the vehicle)
FIG. 1 is a diagram showing a schematic configuration of a vehicle 100 equipped with an in-vehicle secondary battery device 1 according to a first embodiment of the present invention. As shown in this figure, the vehicle 100 of this embodiment is a four-wheeled automobile, and includes a vehicle body 101, a plurality of (four) wheels 103 supporting the vehicle body 101, and a powertrain unit 104 for rotating and driving the wheels 103. The powertrain unit 104 includes a four-stroke engine 105 that is a power source for rotating and driving the wheels 103 (in other words, for running the vehicle), and a transmission 106 that transmits the rotation of the engine 105 to the wheels 103 while changing the speed. The engine 105 and the transmission 106 are mounted in an engine room R provided at the front of the vehicle 100 in a position aligned in the vehicle width direction. In the example of FIG. 1, the engine 105 is a multi-cylinder engine in which four cylinders 110 are formed in an engine body 105a. The engine 105 is mounted in an engine room R with the cylinders 110 aligned in the vehicle width direction and with an exhaust manifold 105b, through which exhaust gas discharged from each cylinder 110 flows, positioned rearward of the engine body 105a.

The vehicle-mounted secondary battery device 1 is a rechargeable secondary battery that is equipped with an electrolyte and an electrode body, and has the functions of supplying power to various electrical devices equipped in the vehicle 100 and charging the battery with power generated by a generator (not shown) such as an alternator attached to the engine 4.

In the first embodiment, the vehicle-mounted secondary battery device 1 is a lithium-ion battery that includes a positive electrode containing lithium and an electrolyte solution made of an organic solvent, and is charged and discharged by the movement of lithium ions between the positive electrode and the negative electrode via the electrolyte solution. Hereinafter, the vehicle-mounted secondary battery device 1 will be simply referred to as the lithium battery 1.

Figure 2 is a schematic front view showing the area around the lithium battery 1 in the engine compartment R. As shown in Figures 1 and 2, the lithium battery 1 is mounted in the engine compartment R. In detail, the lithium battery 1 is disposed above the rear of the transmission 106 in the vehicle fore-and-aft direction (the rear end in the direction of travel when the vehicle 100 moves forward) and in a position relatively close to the exhaust manifold 105b.

Figure 3 is a schematic perspective view of the lithium battery 1. The lithium battery 1 includes a battery case 10 that houses battery cells 20 (described later) inside, and a pair of external terminals 60 (positive and negative external terminals 60). The battery case 10 includes a box-shaped case body 11 that opens upward, and a lid 12 that is attached to the top of the case body 11 and covers the opening of the case body 11. The pair of external terminals 60 protrude upward from the top surface of the lid 12. The battery case 10 corresponds to the "container" in the claims.

As shown in FIG. 2, the lithium battery 1 is mounted on the vehicle 100 so that its up-down direction coincides with the up-down direction based on the vehicle 100, i.e., the direction perpendicular to the ground contact surface of the wheels 3, and so that the "up" based on the lithium battery 1 coincides with the "up" based on the vehicle. In other words, the lithium battery 1 is mounted on the vehicle 100 in a position where the lid 12 is located "above" the case body 11 based on the vehicle 100.

In the following, the up-down direction based on the lithium battery 1 and the up-down direction based on the vehicle 100 are both simply referred to as the "up-down direction." Note that when based on the vehicle 100, the side facing the sky and the side of the lithium battery 1 from the case body 11 toward the lid 12 are "up," and the opposite side is "down."

(Lithium battery)
Fig. 4 is a top view showing the inside of the case body 11 of the lithium battery 1 according to the first embodiment. As shown in Fig. 4, a plurality of battery cells 20 are housed inside the case body 11, i.e., the battery case 10. In the first embodiment, in the case body 11, four battery cells 20 are arranged in a row along the bottom surface 11a of the case 10, i.e., the bottom surface 11a of the case body 11 (the lower surface of the inner surface of the case body 11). Hereinafter, the bottom surface 11a of the case body 11 will be referred to as the case bottom surface 11a as appropriate.

In the first embodiment, as shown in FIG. 1, the lithium battery 1 is mounted on the vehicle 100 with the battery cells 20 aligned along the vehicle longitudinal direction. In other words, when the lithium battery 1 is mounted on the vehicle 100, the orientation of the lithium battery 1 is such that the arrangement direction of the battery cells 20 coincides with the vehicle longitudinal direction (the longitudinal direction based on the vehicle 100). In addition, when the lithium battery 1 is mounted on the vehicle 100, the orientation of the lithium battery 1 is such that the vertical direction based on the lithium battery 1 and the direction perpendicular to the arrangement direction of the battery cells 20, that is, the direction perpendicular to the arrangement direction of the battery cells 20 when viewed from above the vehicle 100, coincides with the vehicle width direction of the vehicle 100.

In the following, the arrangement direction of the battery cells 20 and the vehicle front-rear direction are both simply referred to as the "front-rear direction". In addition, in this "front-rear direction", the front side of the traveling direction when the vehicle moves forward (in the example of FIG. 1, the side from the center of the vehicle body 101 toward the engine room R) is referred to as the "front", and the front side of the traveling direction when the vehicle moves backward (in the example of FIG. 1, the side from the engine room R toward the center of the vehicle body 101) is referred to as the "rear". In the case of the lithium battery 1, the side that is located at the front of the traveling direction when the vehicle moves forward when mounted on the vehicle 100 is the "front", and the opposite side is the "rear". In addition, the vertical direction and the direction perpendicular to the arrangement direction of the battery cells 20 based on the lithium battery 1, and the vehicle width direction of the vehicle 100 are both simply referred to as the "left-right direction", and the right side of the vehicle 100 when facing the front of the vehicle (for the lithium battery 1, the side that becomes the right side when mounted on the vehicle 100) is referred to as the "right", and the left side is referred to as the "left". Note that "front," "back," "right," and "left" in each diagram correspond to the "front," "back," "right," and "left" mentioned above.

Furthermore, in the following description, the battery cell 20 in the front row will be referred to as the first battery cell 20a, the battery cell 20 in the second row from the front will be referred to as the second battery cell 20b, the battery cell 20 in the third row from the front will be referred to as the third battery cell 20c, and the battery cell 20 in the fourth row from the front will be referred to as the fourth battery cell 20d.

Figure 5 is a schematic perspective view of the battery cell 20. Note that Figure 5 illustrates an example of the battery cell 20 in an orientation in which the positive cell side terminal 22a, described later, is on the right side. Figure 6 is a cross-sectional view taken along line VI-VI in Figure 4. Figure 7 is a cross-sectional view taken along line VII-VII in Figure 6. Figure 8 is a schematic perspective view for explaining the structure near the case bottom surface 11a. In Figure 8, the battery cells 20 have been removed from the case body 11, and the rear side wall and right side wall of the case body 11 have been omitted from illustration, in order to clarify the structure near the case bottom surface 11a.

All four battery cells 20 have the same structure. As shown in FIG. 5, the battery cell 20 has an electrode body 25 formed by laminating a positive electrode sheet, a negative electrode sheet, and a separator (none of which are shown), a cell case 21 containing an electrolyte 24, and a pair of cell side terminals 22, 22 connected to the positive electrode sheet and the negative electrode sheet, respectively. One of the cell side terminals 22 is a positive electrode terminal, and the other cell side terminal 22 is a negative electrode terminal. In the following, when the two cell side terminals 22 are described separately, the positive electrode cell side terminal 22a is referred to as the positive electrode cell side terminal 22a, and the negative electrode cell side terminal 22b is referred to as the negative electrode cell side terminal 22b. The pair of cell side terminals 22, 22 corresponds to the "pair of terminals" in the claims, the positive electrode cell side terminal 22a corresponds to the "positive electrode terminal" in the claims, and the negative electrode cell side terminal 22b corresponds to the "negative electrode terminal" in the claims.

The battery cell 20 is a so-called rectangular battery cell, and the cell case 21 is a flat rectangular parallelepiped extending in the left-right direction. The two cell side terminals 22 are arranged side by side in the left-right direction on the upper surface 21a of the cell case 21 and protrude upward from the upper surface 21a of the cell case 21. The two cell side terminals 22 are arranged at positions spaced apart from each other across a center line O2 that bisects the cell case 21 in the left-right direction when viewed from above the vehicle 100 in a plan view, that is, when viewed from above the vehicle 100. In the first embodiment, the two cell side terminals 22, 22 are arranged at positions symmetrical to the left and right with the center line O2 as the center. In the following, as described above, when viewed from above the vehicle 100, the term "plan view" will be used to simply refer to the state when viewed from above the vehicle 100.

In the lower portion 21d of the cell case 21, that is, the portion below the line O1 (the vertical center line of the cell case 21) that vertically bisects the cell case 21, an open valve 23 is provided that opens to communicate between the inside and outside of the cell case 21 when the pressure inside the cell case 21, that is, the internal pressure of the cell case 21, reaches a predetermined value or more. In the first embodiment, the open valve 23 is provided on the lower surface 21b of the cell case 21. The specific configuration of the open valve 23 is not limited, but for example, the open valve 23 is configured to break when pressure of a predetermined value or more is applied from inside the cell case 21 to communicate between the inside and outside of the cell case 21. Hereinafter, the lower surface 21b of the cell case 21 will be referred to as the cell case lower surface 21b as appropriate.

The release valve 23 is provided on one side of the center line O2 of the cell case lower surface 21b in the left-right direction. In other words, the release valve 23 is provided on a portion of the cell case lower surface 21b that is biased toward one of the cell side terminals 22 from the center line O2 in the arrangement direction of the pair of cell side terminals 22. In the first embodiment, the release valve 23 is provided on a portion that is biased toward the positive cell side terminal 22a.

As shown in FIG. 4, the four battery cells 20 are arranged so that the center line O2 of each cell case 21 coincides with a reference line O20 extending in the front-rear direction. The four battery cells 20 are housed in the case body 11 so that, for two adjacent battery cells 20, the positive cell side terminal 22a of one battery cell 20 and the negative cell side terminal 22b of the other battery cell 20 are aligned in a straight line in the front-rear direction. In other words, the four battery cells 20 are arranged so that their left and right orientations alternate from the front.

Due to the arrangement of the battery cells 20, the positions of the release valve 23 of one battery cell 20 and the release valve 23 of the other battery cell 20 are different from each other in the left-right direction relative to the reference line O20, and are offset from each other in the left-right direction.

In the example of FIG. 4, the first battery cell 20a and the third battery cell 20c are housed in the case body 11 with their positive cell side terminals 22a facing right (to the right of the center line O2 and the reference line O20), and the second battery cell 20b and the fourth battery cell 20d are housed in the case body 11 with their positive cell side terminals 22a facing left (to the left of the center line O2 and the reference line O20). The release valves 23 are arranged from the front to the right, left, right, left, across the reference line O20.

Between the case bottom surface 11a and each cell case lower surface 21b, there are disposed a plurality of partition walls 30 that partition the space therebetween, and a liquid-absorbing material 40 capable of absorbing the electrolyte. Hereinafter, the space between the case bottom surface 11a and each cell case lower surface 21b will be referred to as the case bottom space X1, where appropriate.

In the first embodiment, the absorbent material 40 is made of organic fibers, which has a lower thermal conductivity than those made of metals such as steel wool or glass wool.

Each partition wall 30 has a rectangular plate shape that is perpendicular to the front-to-rear direction and extends upward from the case bottom surface 11a. The vertical dimensions of each partition wall 30 are the same.

A pair of left and right main partition walls 31, 31 are provided as partition walls 30 in the center of the front-rear direction of the case bottom space X1. These two main partition walls 31, 31 have a plate shape extending in the left-right direction, and are arranged side by side with a gap C1 in the center of the left-right direction of the case bottom space X1. Specifically, the right main partition wall 31 extends from the right inner surface 11b of the case body 11 to a position between the release valve 23 (the release valves 23 of the first battery cell 20a and the third battery cell 20c) provided to the right of the reference line O20 and the release valve 23 (the release valves 23 of the second battery cell 20b and the fourth battery cell 20d) provided on the left side. The left main partition wall 31 extends from the left inner surface 11c of the case body 11 to a position between the release valves 23 (the release valves 23 of the first battery cell 20a and the third battery cell 20c) provided to the right of the reference line O20 and the release valves 23 (the release valves 23 of the second battery cell 20b and the fourth battery cell 20d) provided on the left side, and to a position to the left of the left end of the right main partition wall 31.

The liquid-absorbent material 40 is placed on the case bottom surface 11a. The liquid-absorbent material 40 is disposed at a position that does not overlap with the release valve 23 in a plan view. The vertical dimension of the liquid-absorbent material 40 is set to be the same as the vertical dimension of each partition wall 30. The vertical dimensions of the liquid-absorbent material 40 and partition walls 30 match the vertical separation distance between the cell case bottom surface 21b and the case bottom surface 11a, and each battery cell 20 is placed on the partition walls 30 and liquid-absorbent material 40.

In the area of the case bottom space X1 forward of the main partition wall 31, a first liquid absorbing member 41 and a second liquid absorbing member 42 are arranged as the liquid absorbing material 40, which are opposed in the left-right direction across an area including the release valves 23 of the first battery cell 20a and the second battery cell 20b in a plan view.

The first liquid suction member 41 has a rectangular parallelepiped shape and is laid over the entire area of the case bottom space X1, which is in front of the main partition wall 31 and slightly spaced to the right of the release valve 23. The second liquid suction member 42 has a structure symmetrical to the first liquid suction member 41, has a rectangular parallelepiped shape, and is laid over the entire area of the case bottom space X1, which is in front of the main partition wall 31 and slightly spaced to the left of the release valve 23.

In the space between the first battery cell 20a and the case bottom surface 11a, which is included in the area of the case bottom space X1 forward of the main partition wall 31, a right partition wall 32 extending leftward from the left edge of the first liquid suction member 41 is provided as a partition wall 30. In a plan view, the right partition wall 32 extends leftward from the first liquid suction member 41, passing behind the release valve 23 of the first battery cell 20a. The left-right dimension of the right partition wall 32 is shorter than the left-right separation distance between the first liquid suction member 41 and the second liquid suction member 42, and a gap C2 is formed between the right partition wall 32 and the second liquid suction member 42.

In the space between the second battery cell 20b and the case bottom surface 11a, which is included in the area of the case bottom space X1 forward of the main partition wall 31, a left partition wall 33 extending rightward from the left edge of the second liquid suction member 42 is provided as a partition wall 30. In a plan view, the left partition wall 33 extends rightward from the second liquid suction member 42, passing in front of the release valve 23 of the second battery cell 20b. The left-right dimension of the left partition wall 33 is shorter than the left-right separation distance between the first liquid suction member 41 and the second liquid suction member 42, and a gap C3 is formed between the left partition wall 33 and the first liquid suction member 41.

The structure of the case bottom space X1 is the same on the front and rear sides of the main partition walls 31, 31. That is, the area of the case bottom space X1 behind the main partition wall 31 also has a first liquid suction member 41 laid in the area to the right of the open valve 23 and a second liquid suction member 42 laid in the area to the left of the open valve 23. Also, the area of the case bottom space X1 behind the main partition wall 31 also has a right partition wall 32 extending leftward from the left edge of the first liquid suction member 41 between the third battery cell 20c and the case bottom surface 11a, passing behind the open valve 23 of the third battery cell 20c, and a left partition wall 33 extending rightward from the right edge of the second liquid suction member 42, passing in front of the open valve 23 of the fourth battery cell 20d between the fourth battery cell 20d and the case bottom surface 11a.

Here, in the area in front of the main partition walls 31, 31 of the case bottom space X1, the first battery cell 20a corresponds to the "front battery cell" in the claims, the second battery cell 20b corresponds to the "rear battery cell" in the claims, the right partition wall 32 provided in this area corresponds to the "first partition wall" in the claims, and the left partition wall 33 corresponds to the "second partition wall" in the claims. In addition, in the area behind the main partition walls 31, 31 of the case bottom space X1, the third battery cell 20c corresponds to the "front battery cell" in the claims, the fourth battery cell 20d corresponds to the "rear battery cell" in the claims, the right partition wall 32 provided in this area corresponds to the "first partition wall" in the claims, and the left partition wall 33 corresponds to the "second partition wall" in the claims.

(Functions of the First Embodiment)
As described above, in the lithium battery 1 according to the first embodiment, the cell case 21 is provided with the release valve 23 that opens to communicate between the inside and outside of the cell case 21 when the internal pressure of the cell case 21 reaches or exceeds a predetermined value. This makes it possible to prevent the internal pressure of the cell case 21 from increasing excessively, causing the cell case 21 to burst or the like.

Moreover, in this lithium battery 1, an open valve 23 is provided at the lower part 21d of the cell case 21, and a liquid absorbing material 40 capable of absorbing the electrolyte is provided between the cell case lower surface 21b and the case bottom surface 11a facing the cell case lower surface 21b. Therefore, the liquid electrolyte that has accumulated at the bottom of the cell case 21, rather than the gasified electrolyte that has accumulated at the top of the cell case 21, is allowed to flow out of the cell case 21 through the open valve 23, thereby reducing the internal pressure of the cell case 21. Therefore, while preventing the internal pressure of the cell case 21 from becoming excessively high, it is possible to suppress leakage of the gasified electrolyte to the outside of the cell case 21 and further to the outside of the battery case 10. Therefore, while the lithium battery 1 is mounted in the engine room R, it is possible to prevent the gasified electrolyte from coming into contact with various high-temperature devices in the engine room R and further increasing in temperature. In particular, the exhaust manifold 105b is prone to becoming hot due to the high-temperature exhaust gas flowing through it, and if the lithium battery 1 is disposed relatively close to the exhaust manifold 105b as described above, there is a risk that the gasified electrolyte may become hot due to contact with the exhaust manifold 105b and ignite. In contrast, in the first embodiment, the leakage of the gasified electrolyte and liquid electrolyte to the outside of the battery case 10 is prevented, so that the electrolyte can be reliably prevented from igniting, and a high level of safety can be ensured while arranging the lithium battery 1 close to the exhaust manifold 105b.

In particular, in the first embodiment, the release valve 23 is provided on the bottom surface 21b of the cell case. This can reliably prevent the gasified electrolyte that accumulates at the top of the cell case 21 from leaking out of the cell case 21 through the release valve 23.

In the first embodiment, the first liquid suction member 41 and the second liquid suction member 42 are disposed at positions spaced apart from each other in the left-right direction. The two first liquid suction members 41 and the two second liquid suction members 42 are also separated from each other via the main partition wall 31. As a result, even if the liquid suction power of any one of the four liquid suction members 41, 42 decreases due to deterioration or the like, the other liquid suction members 41, 42 can absorb the electrolyte. Therefore, leakage of the electrolyte to the outside of the battery case 10 can be more reliably prevented. For example, in the first embodiment, even if the first liquid suction member 41 disposed on the rear right side of the case bottom space X1 is thermally deteriorated by receiving radiant heat from the exhaust manifold 105b and its liquid suction power decreases, the remaining first liquid suction member 41 and the two second liquid suction members 42 can absorb the electrolyte.

In addition, in the first embodiment, each release valve 23 is provided at a position that does not overlap with the release valve 23 in a plan view.

Therefore, even if the absorbing power of the liquid-absorbing material 40 decreases due to deterioration or the like, the liquid-absorbing material 40 can be prevented from blocking the release valve 23. This makes it possible to more reliably allow the electrolyte to flow out of the cell case 21 and suppress an excessive increase in the internal pressure of the cell case 21.

In addition, in the first embodiment, the release valves 23 are arranged alternately on the left and right sides of the reference line O20, starting from the front. In other words, the distance between these release valves 23 is longer than when the release valves 23 of two adjacent battery cells 20 are arranged in a row in the front-to-rear direction. This prevents electrolyte that flows out of one of the release valves 23 of the adjacent battery cells 20 from flowing into the periphery of the other release valve 23 and interfering with the outflow of electrolyte from this other release valve 23. This allows electrolyte to flow out smoothly from each release valve 23, and the internal pressure of each cell case 21 can be reduced more reliably and quickly.

In particular, in the first embodiment, the alternating arrangement of the release valves 23 is realized by changing the left and right orientation of the battery cells 20 having the same structure. Specifically, a pair of cell side terminals 22 are arranged in the left-right direction on the upper surface 21a of the cell case 21 as the battery cell 20, and the release valve 23 is provided on the positive cell side terminal 22a side of the center line O2 in the left-right direction of the cell case 21. The four battery cells 20 are accommodated in the case body 11 so that the center line O2 coincides with the reference line O20, and the positive cell side terminal 22a of one of the two adjacent battery cells 20 and the negative cell side terminal 22b of the other are linearly arranged in the front-rear direction, thereby realizing the alternating arrangement of the release valves 23. Therefore, in order to realize this arrangement, it is not necessary to prepare multiple battery cells 20 with different structures, which is advantageous in terms of cost.

In the first embodiment, a first liquid suction member 41 and a second liquid suction member 42 are disposed in the space between the first battery cell 20a and the second battery cell 20b and the case bottom surface 11a, and are opposed in the left-right direction across the area including the release valve 23. The right-side partition wall 32 extends from the first liquid suction member 41 to a position to the left of the second liquid suction member 42, passing behind the release valve 23 of the first battery cell 20a, between the first battery cell 20a and the case bottom surface 11a, in a plan view. The left-side partition wall 33 extends from the second liquid suction member 42 to a position to the left of the first liquid suction member 41, passing in front of the release valve 23 of the second battery cell 20b, between the second battery cell 20b and the case bottom surface 11a, in a plan view. In addition, a first liquid suction member 41 and a second liquid suction member 42 having a similar configuration are disposed in the space between the third battery cell 20c and the fourth battery cell 20d and the case bottom surface 11a, and a right partition wall 32 and a left partition wall 33 having a similar configuration are also provided.

In the first embodiment, this structure can prevent the electrolyte that has flowed out of the release valve 23 of one of the two battery cells 20 adjacent in the front-rear direction from flowing toward the other battery cell 20, and can allow the electrolyte to be quickly absorbed by the liquid-absorbing members 41, 42. This can reliably prevent the temperature and pressure of the other battery cell 20 from increasing due to the high-temperature electrolyte that has flowed out.

This will be explained in detail using Figures 9 and 10.

9 shows an example in which the open valve 23 of the fourth battery cell 20d is open. When the open valve 23 is open, the electrolyte flows out downward. The electrolyte tries to move in all four directions of the open valve 23, but the movement of the electrolyte forward is restricted by the left partition wall 33. As a result, the electrolyte moves only in the left and right directions as shown by the arrows Y1 and Y2. As shown by the arrow Y1, the electrolyte that moves to the left is absorbed by the second liquid suction member 42. Here, the distance between the open valve 23 of the fourth battery cell 20d and the second liquid suction member 42 is relatively short. Therefore, a large amount of the liquid suction material is absorbed by the second liquid suction member 42 early. In addition, as shown by the arrow Y2, the electrolyte that moves to the right is absorbed by the first liquid suction member 41. Therefore, the amount of electrolyte that moves forward through the gap C3, that is, toward the third battery cell 20c, is kept small. Furthermore, as shown by the arrow Y3, the electrolyte that moves forward through the gap C3 is also guided to the left by the right partition wall 32. Therefore, most of the electrolyte that passes through the gap C3 is absorbed by the first liquid absorbing member 41.

In this way, the amount of electrolyte that reaches the main part of the third battery cell 20c is kept very small, and the temperature of the third battery cell 20c is prevented from increasing due to the high-temperature electrolyte.

As described above, the electrolyte that flows out from the fourth battery cell 20d is absorbed by the first and second liquid suction members 41 and 42, respectively. Therefore, even if the suction power of one of the first and second liquid suction members 41 and 42 is reduced due to deterioration or the like, the electrolyte can be absorbed by the other, and the electrolyte can be reliably absorbed by the liquid suction material 40. In particular, the first and second liquid suction members 41 and 42 are each set to a size that spans two battery cells 20. Therefore, even if only one of the liquid suction members 41 and 42 can absorb the electrolyte, the electrolyte can be reliably absorbed by it.

In the first embodiment, the left-right dimensions of the right-side partition wall 32 and the left-side partition wall 33 are shorter than the distance between the first liquid-absorbing member 41 and the second liquid-absorbing member 42 to form the gaps C1 and C2. Alternatively, the left-right dimensions of the right-side partition wall 32 and the left-side partition wall 33 may be set to the same as the distance so that the gaps C1 and C2 are not formed. However, if the gaps C1 and C2 are formed, when the liquid-absorbing power of any of the four liquid-absorbing members 41 and 42 is reduced, the electrolyte can be diffused through the gaps C1 and C2, and it is possible to prevent high-temperature electrolyte from remaining around the open release valve 23 and hindering the outflow of new electrolyte.

Figure 10 shows an example in which the release valve 23 of the third battery cell 20c is open. In this example, the right partition wall 32 and the left partition wall 33 restrict the movement of the electrolyte toward the fourth battery cell 20d, and the electrolyte is guided to the first liquid suction member 41 and the second liquid suction member 42, so that the amount of electrolyte that reaches the fourth battery cell 20d is kept small. In addition, the first liquid suction member 41 arranged in a position close to the open release valve 23 absorbs the electrolyte early. This suppresses the rise in temperature of the fourth battery cell 20d due to the high-temperature electrolyte. In addition, as shown by the arrow Y13, some of the electrolyte flows into the second battery cell 20b through the gap C1, but the main partition wall 31 and the right partition wall 32 make the flow direction of the electrolyte along these partition walls 30, that is, the left-right direction, as shown by the arrows Y11 and Y12, so that the amount of electrolyte that flows into the second battery cell 20b is kept small. This also prevents the temperature of the second battery cell 20b from rising due to high-temperature electrolyte.

Also, as in the example of FIG. 9, the electrolyte that flows out from the third battery cell 20c is absorbed by the first liquid-suction member 41 and the second liquid-suction member 42, respectively. Therefore, even if the absorbing power of one of the first liquid-suction member 41 and the second liquid-suction member 42 is reduced due to deterioration or the like, the electrolyte can be absorbed by the other, and the electrolyte can be reliably absorbed by the liquid-suction material 40.

In the first embodiment, the two main partition walls 31 are arranged with a gap C1, but the main partition walls 31 may be arranged to close the gap C1. In other words, the main partition walls 31 may be arranged over the entire left and right sides of the case body 11. However, if the gap C1 is formed, when the liquid absorption ability of the liquid-absorbent material 40 behind the main partition wall 31 is reduced, the electrolyte can be moved forward from the main partition wall 31 to be absorbed by the liquid-absorbent material 40 in front of the main partition wall 31. Therefore, the electrolyte can be more reliably absorbed into the liquid-absorbent material 40. In addition, it is possible to prevent high-temperature electrolyte from remaining around the open release valve 23 and hindering the outflow of new electrolyte.

Second Embodiment
Next, an in-vehicle secondary battery device 1 according to a second embodiment of the present invention will be described. Below, configurations different from those of the first embodiment will be described. Fig. 11 is a top view showing the inside of a case body 211 of a lithium battery 201 according to the second embodiment, and corresponds to Fig. 5 of the first embodiment. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 12, and corresponds to Fig. 7 of the first embodiment. Note that components having the same configuration as those of the first embodiment will be described with the same reference numerals as those of the first embodiment.

In the second embodiment, as in the first embodiment, four battery cells 20 (from the front, the first battery cell 20a, the second battery cell 20b, the third battery cell 20c, and the fourth battery cell 20d) are arranged side by side in the front-rear direction along the case bottom surface 211a, which is the bottom surface of the case main body 211.

Meanwhile, in the second embodiment, an open valve 23 is provided at the lower part of the right side surface 21c of the cell case 21 of each battery cell 20 (the part below the vertical center line O1 of the cell case 21). For example, the open valve 23 is provided at a position about one-sixth of the vertical dimension of the cell case 21 above the lower end of the cell case 21. In addition, a relatively large space is defined between each cell case 21 and the right inner surface 211b of the case main body 211. Hereinafter, this space will be referred to as the case right space X21 where appropriate.

In the second embodiment, three partition walls 250 are provided in the case right space X21 aligned in the front-rear direction. These partition walls 250 have the same structure. The partition walls 250 are plate-shaped and perpendicular to the front-rear direction. Each partition wall 250 extends from a position slightly above the release valve 23 to the case bottom surface 211a in the vertical direction. Each partition wall 250 is provided at the boundary between two adjacent battery cells 20 in the front-rear direction, and divides the two adjacent release valves 23 from each other in a side view (when viewed from the right). The left and right edges of each partition wall 250 are in contact with the right side surface 21c of the two adjacent cell cases 21 and the right inner surface 211b of the case main body 211 over the entire vertical direction. Hereinafter, the three partition walls 250 are appropriately referred to as the first partition wall 250a, the second partition wall 250b, and the third partition wall 250c, in order from the front.

As in the first embodiment, a plurality of partition walls 230 that partition the space between the case bottom surface 211a and each cell case bottom surface 21b, and a plurality of liquid absorbing materials 240 capable of absorbing electrolyte are arranged in the case bottom space X1 between the case bottom surface 211a and each cell case bottom surface 21b. In the second embodiment, each partition wall 230 has a plate shape and extends upward from the case bottom surface 211a. In the second embodiment, each liquid absorbing material 240 has a rectangular parallelepiped shape and is placed on the case bottom surface 211a. The vertical dimensions of each partition wall 230 and liquid absorbing material 240 match the dimensions between the case bottom surface 211a and each cell case bottom surface 21b, and each battery cell 20 is placed on these partition walls 230 and liquid absorbing materials 240. However, the arrangement of these is different between the second embodiment and the first embodiment.

In the second embodiment, a first main partition wall 231 and a second main partition wall 232 are arranged as partition walls 230 in the center of the case bottom space X1 in the front-to-rear direction.

The first main partition wall 231 extends leftward from the left edge of the lower part of the second partition wall 250b. The second main partition wall 232 extends leftward from a position to the left of the left end of the first main partition wall 231. The second main partition wall 232 extends from the left inner surface 211c of the case body 211 to a position spaced to the right.

In the second embodiment, the first liquid-absorbent material 241 is disposed as the liquid-absorbent material 40 on the left side of the second main partition wall 232. The first liquid-absorbent material 241 is laid over the entire area of the case bottom space X1 to the left of the left end of the second main partition wall 232 in the left-right direction. In the illustrated example, the first liquid-absorbent material 241 occupies approximately one-third of the area of the case bottom space X1.

In the front region of the case bottom space X1, a vertical partition wall 233 extending in the front-rear direction is disposed as the partition wall 230. The vertical partition wall 233 is disposed so that its central portion in the front-rear direction is in contact with the left side of the lower end portion of the first partition wall 250a. The front-rear dimension of the vertical partition wall 233 is approximately the same as the front-rear dimension of the cell case 21, and in the front-rear direction, the vertical partition wall 233 extends from near the center of the first battery cell 20a to near the center of the second battery cell 20b.

In the front area of the case bottom space X1, a pair of first horizontal partition walls 234, 234 are disposed, extending leftward from both front-rear edges of the vertical partition wall 233. In the left-right direction, each first horizontal partition wall 234 extends leftward beyond the right edge of the second main partition wall 232.

The vertical partition wall 233 and the two first horizontal partition walls 234, 234 divide a part of the front area of the case bottom space X1 into a U-shape, and a second liquid-absorbent material 242 is laid as the liquid-absorbent material 240 in the space surrounded by the vertical partition wall 233 and the two first horizontal partition walls 234, 234.

In addition, a second horizontal partition wall 235 is provided in the front area of the case bottom space X1, extending rightward from the right edge of the first liquid-absorbing material 241 at the boundary between the first battery cell 20a and the second battery cell 20b. The second horizontal partition wall 235 extends to a position spaced to the left from the left edges of the first horizontal partition wall 234 and the second liquid-absorbing material 242.

The portions of the case bottom space X1 in front of and behind the main partition walls 231 and 232 have the same structure. That is, the portions of the case bottom space X1 in rear of the main partition walls 231 and 232 are also provided with a vertical partition wall 233 that contacts the left side of the lower end of the third partition wall 250c and extends from near the center of the third battery cell 20c to near the center of the fourth battery cell 20d in the front-rear direction. In addition, two first horizontal partition walls 234 are provided that extend leftward from both edges of the vertical partition wall 233 in the front-rear direction, and a second liquid-absorbing material 242 is laid between the vertical partition wall 233 and the first horizontal partition wall 234. In addition, a second horizontal partition wall 235 that extends rightward from the right edge of the first liquid-absorbing material 241 is provided at the boundary between the third battery cell 20c and the fourth battery cell 20d.

(Functions of the Second Embodiment)
As described above, in the lithium battery 201 of the second embodiment, an open valve 23 is provided in the lower part 21d of the cell case 21, and a liquid-absorbing material 240 is provided between the cell case lower surface 21b and the case bottom surface 211a, thereby preventing the internal pressure of the cell case 21 from becoming excessively high while suppressing leakage of gasified electrolyte from the cell case 21 and even to the outside of the battery case 10.

Here, if the release valve 23 is provided on the underside a of the cell case 21 as in the first embodiment, the discharge of the electrolyte can be promoted by both the internal pressure of the cell case 21 and the weight of the electrolyte. On the other hand, in this configuration, even after the internal pressure of the cell case 21 has sufficiently decreased, the electrolyte may be discharged from the release valve 23 to the outside of the cell case 21 due to its own weight. In contrast, in the second embodiment, the release valve 23 is provided on the right side surface 21c of the cell case 21, so that the electrolyte can be prevented from being excessively discharged to the outside of the cell case 21 due to its own weight, and the amount of electrolyte flowing out to the outside of the cell case 21 can be kept small while reducing the internal pressure of the cell case 21.

Also, in the second embodiment, the three liquid-absorbing materials 240 (the first liquid-absorbing material 241 and the two second liquid-absorbing materials 242) are arranged spaced apart from each other, so that even if the absorbing power of some of the liquid-absorbing materials 240 decreases, leakage of the electrolyte to the outside of the battery case 10 can be more reliably prevented.

Also, in the second embodiment, the open valves 23 are separated from each other by the partition wall 250. This makes it possible to prevent the electrolyte that flows out of one of the open valves 23 of two adjacent battery cells 20 from flowing toward the other battery cell 20, and to prevent the other battery cell 20 from increasing in temperature and pressure due to the high-temperature electrolyte that flows out.

Also, in the second embodiment, multiple partition walls 230 are arranged in the case bottom space X1, and the first liquid-absorbing material 241 and the second liquid-absorbing material 242 are arranged as described above, so that the electrolyte can be reliably absorbed by the liquid-absorbing material 240, and the battery cells 20 whose release valves 23 are not open can be prevented from increasing in temperature and pressure due to high-temperature electrolyte.

Specifically, as shown by arrow Y21 in FIG. 15, which corresponds to FIG. 13, when the release valve 23 of the fourth battery cell 20d is opened, the partition wall 250, the rear vertical partition wall 233, and the rear first horizontal partition wall 234 guide the electrolyte to the passage between the rear first horizontal partition wall 234 and the rear inner surface 211e of the case body 211. As a result, most of the electrolyte is guided to the left and absorbed by the first liquid-absorbing agent 410. Also, as shown by arrow Y22, some of the electrolyte moving forward is absorbed by the second liquid-absorbing material 242 along the way.

The second horizontal partition wall 235 is spaced to the left from the left edge of the second liquid-absorbing material 242 that faces it, and a gap C22 is formed between them. Therefore, when the amount of electrolyte flowing out is large, some of the electrolyte moves through this gap C22 toward the third battery cell 20c. However, as described above, most of the electrolyte is absorbed by the first liquid-absorbing materials 241, 242 before it reaches the third battery cell 20c, so the amount of electrolyte that reaches the third battery cell 20c is kept small.

And because the gap C22 is provided as described above, even if the absorbing capacity of the first liquid-absorbing material 40 is reduced, the electrolyte can be moved to the front second liquid-absorbing material 240 through the gap C22 and the gap C21 between the first main partition wall 231 and the second main partition wall 232, as shown by the arrow Y3, and can be absorbed by it.

(Modification)
In the first and second embodiments, the case where four battery cells 20 are housed in the battery case 10 has been described. However, the number of battery cells 20 housed in the battery case 10 is not limited to this.

The location where the release valve 23 is disposed may be the lower portion 21d of the cell case 21, and is not limited to the above. In the first embodiment, the release valve 23 may be disposed on the negative cell side terminal 22b side of the reference line O20 in the left-right direction.

The arrangement of the liquid-absorbent material 40 and the partition wall 30 is not limited to the above. For example, the liquid-absorbent material 40 may be laid throughout the entire case bottom space X1. The partition wall 30 may also be omitted.

The lithium battery 1 may have a structure in which the structures of the first and second embodiments are inverted in the left-right direction. In other words, a structure in which "right" is read as "left" and "left" is read as "right" in the explanations and drawings of the first and second embodiments may be used.

Furthermore, the vehicle mounting position of the lithium battery 1 is not limited to the above. For example, the lithium battery 1 may be mounted on the vehicle 100 with the battery cells 20 aligned in the vehicle width direction.

Furthermore, the vehicle-mounted secondary battery device according to the present invention is not limited to lithium batteries.

1 Lithium battery (secondary battery device)
10 Battery case (container)
20 Battery cell 21 Cell case 22 Terminal 22a Positive cell side terminal (positive terminal)
22b Negative cell side terminal (negative terminal)
23 Release valve 24 Electrolyte 25 Electrode body 30 Partition wall 32 Right side partition wall (first partition wall)
33 Left side partition wall (second partition wall)
40 Liquid-absorbent material 41 First liquid-absorbent member 42 Second liquid-absorbent member 250 Partition wall O2 Center line O20 Reference line

Claims (5)

A secondary battery device mounted on a vehicle,
a battery cell including a cell case that accommodates an electrode assembly and an electrolyte, a pair of terminals, and an open valve that is provided at a lower portion of the cell case and opens to communicate between the inside and the outside of the cell case when the pressure inside the cell case reaches or exceeds a predetermined value;
A container that houses the battery cell therein;
a liquid-absorbent material that is disposed between a lower surface of the cell case and a bottom surface of the storage container facing the lower surface of the cell case and is capable of absorbing the electrolyte ;
The release valve is provided on a lower surface of the cell case,
The vehicle-mounted secondary battery device , wherein the liquid absorbing material is provided at a position not overlapping with the release valve when viewed from above the vehicle. 2. The vehicle-mounted secondary battery device according to claim 1 ,
a plurality of the battery cells arranged in a row along a bottom surface of the container;
When a direction in which the plurality of battery cells are arranged is defined as a front-rear direction and a direction perpendicular to the front-rear direction when viewed from above the vehicle is defined as a left-right direction, the plurality of battery cells include a front battery cell and a rear battery cell adjacent to each other in the front-rear direction,
the release valve of the front battery cell is provided at a position shifted to one side in the left-right direction with respect to a reference line extending in a front-rear direction,
The vehicle-mounted secondary battery device, characterized in that the release valve of the rear battery cell is provided at a position shifted to the other side in the left-right direction with respect to the reference line. 3. The vehicle-mounted secondary battery device according to claim 2 ,
The pair of terminals is a positive terminal and a negative terminal that are arranged to be spaced apart from each other across a center line that bisects the cell case in the left-right direction,
the release valve is provided at a position biased toward either the positive electrode terminal or the negative electrode terminal from the center line on the lower surface of the cell case,
the front battery cell and the rear battery cell are arranged such that the center lines of both battery cells coincide with the reference line, and the positive terminal of one battery cell and the negative terminal of the other battery cell are aligned in a straight line in the fore-and-aft direction. 4. The vehicle-mounted secondary battery device according to claim 2 ,
the liquid absorbing material has a first liquid absorbing member and a second liquid absorbing member that face each other in the left-right direction across an area including the open valves of the front battery cell and the rear battery cell when viewed from above the vehicle,
a first partition wall is provided between the front battery cell and a bottom surface of the storage container, the first partition wall extending from the first liquid suction member toward the second liquid suction member through a rear of the open valve of the front battery cell when viewed from above the vehicle;
a second partition wall is provided between the rear battery cell and a bottom surface of the storage container, the second partition wall extending from the second liquid suction member toward the first liquid suction member, passing in front of the release valve of the rear battery cell when viewed from above the vehicle;
a gap is formed between the first partition wall and the second liquid absorbing member, and between the second partition wall and the first liquid absorbing member, 2. The vehicle-mounted secondary battery device according to claim 1,
a plurality of the battery cells arranged in a row along a bottom surface of the container;
When the direction in which the plurality of battery cells are arranged is defined as a front-rear direction, and the direction perpendicular to the front-rear direction when viewed from above the vehicle is defined as a left-right direction,
The release valve of each battery cell is provided at a lower portion of a side surface on one of the left and right sides of the cell case,
an inner surface of the storage container facing the open valve of each of the battery cells is provided with a partition wall that separates the open valve of one of two adjacent battery cells from the open valve of the other battery cell in a front-to-rear direction in a side view.

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