JP2017152322A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which enables the suppression of deposition of an electrolytic solution to an inlet in manufacturing.SOLUTION: A secondary battery comprises: a battery case including a casing and a lid; a power-generating element encased in the battery case; an inlet provided in the lid, through which an electrolytic solution is injected into the battery; and a filter part 50 provided on the inlet for circulating the electrolytic solution 75 supplied from outside the battery case. The filter part 50 has a plurality of hole parts 51 running through itself from outside the battery case to the inside. A direction of each hole part 51 running through the filter part is inclined with respect to a direction of injecting the electrolytic solution; and the size (opening width "a") of opening of each hole part when viewed from the direction of each hole part running through the filter is larger than the size (opening width "b") of opening of the hole part when viewed from the injecting direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a secondary battery including an electrode plate group and an electrolytic solution in a battery case.

  Usually, in a manufacturing process of a secondary battery, an electrolytic solution is injected into a battery case that accommodates an electrode plate group. In this electrolytic solution injection process, it is necessary to prevent foreign matter from entering the battery case, particularly metal pieces. An example of a technique for preventing such foreign matter from entering the battery case is described in Patent Document 1.

  The secondary battery described in Patent Document 1 includes a battery case (battery can) formed by closing an inlet (opening) of a can body that accommodates an electrode plate group (battery element) with a lid (lid member); A non-aqueous electrolyte secondary battery including a non-aqueous electrolyte injected into a tank includes an insulating plate interposed between an electrode plate group and a lid. The insulating plate is provided with a plate-like insulating plate main body penetrating the injection hole, and on one side of the insulating plate main body, a filter member made of a non-woven fabric that can penetrate only the electrolytic solution is provided so as to cover the injection hole.

Japanese Patent No. 4748193

  According to the secondary battery described in Patent Document 1, since the filter member made of nonwoven fabric allows only the electrolytic solution to permeate, foreign matters such as metal pieces are mixed into the battery case from the inlet of the can body when the electrolytic solution is injected. Is prevented.

  By the way, in the manufacturing process of the secondary battery, along with the shortening of the time required for the injection of the electrolyte, it is possible to prevent the electrolyte from adhering to the injection port, which causes the welding failure of the sealing member that seals the injection port. Is desired. However, since the nonwoven fabric itself retains the electrolytic solution, if the supply is too large, the electrolytic solution floats on the nonwoven fabric, causing liquid splashing, which may adhere to the injection port.

  This invention is made | formed in view of such a situation, The objective is to provide the secondary battery which can suppress that electrolyte solution adheres to an injection port in manufacture.

  A secondary battery that solves the above problem is a secondary battery in which a power generation element is accommodated in a battery case composed of a case and a lid, and is provided on the lid and is injected with an electrolyte And a filter part that is provided in the inlet and allows the electrolyte solution supplied from outside the battery case to circulate, wherein the filter part has a plurality of holes that penetrate from the outside to the inside of the battery case. And each of the holes has a direction in which the hole penetrates with respect to a direction in which the electrolyte is injected, and penetrates more than a size of the opening viewed from the direction in which the electrolyte is injected. The size of the opening seen from the direction is larger.

  When the electrolytic solution is injected, the electrolytic solution that has passed through the filter portion immediately hits the electrode plate group, so that the liquid splashes due to contact with the electrode plate group or temporary residence in the vicinity of the electrode plate group. The splashed splash may pass through the hole of the filter part and adhere to the inlet. In this respect, according to such a configuration, the hole has an inclination in the direction in which the electrolytic solution is injected, that is, the direction in which the electrolytic solution flows down, and the apparent opening becomes small. The risk that the splashes will pass through the hole and adhere to the injection port is reduced. And since electrolyte solution is filtered by the hole of a filter part on that, mixing of the foreign material in a battery case is suppressed, and generation | occurrence | production of the inconvenience etc. which arise in a battery by mixing of a foreign material is also suppressed. Become.

As a preferred configuration, the size of the opening viewed from the injection direction is 25% or less and 2% or more of the size of the opening viewed from the penetrating direction.
According to such a configuration, it is possible to achieve both the effect of suppressing the passage of splashes of liquid splash and the effect of suppressing the retention of the electrolytic solution in the filter part.

As a preferred configuration, the electrolytic solution contains a non-aqueous electrolyte.
According to such a configuration, the possibility of poor welding at the inlet due to the nonaqueous electrolyte is reduced.

As a preferred configuration, the opening of the hole portion viewed from the penetrating direction has a shortest opening distance set to 100 micrometers or less.
According to such a configuration, intrusion of foreign matters larger than 100 micrometers is prevented, and thus the possibility that such foreign matters short-circuit the electrode plate group and the outer wall of the battery case is reduced.

  As a preferred configuration, the filter portion is made of a plate material, and a plurality of portions of the plate material are formed with steps in the injection direction, and the hole portion is formed in the step portion.

  According to such a configuration, by making the plate material different in level, it is possible to provide a hole having a larger opening in the penetrating direction than the size of the opening in the injection direction. Note that the hole can be formed by, for example, shearing a plate material at a step portion when press forming a step.

As a preferred configuration, the filter portion is a bottomed cylindrical body extending from the inlet into the battery case, and the hole portion is provided on a peripheral side surface of the cylindrical body.
According to such a configuration, since the penetrating direction is orthogonal or nearly orthogonal to the injection direction, the splashed electrolyte solution in the battery case passes through the hole and adheres to the injection port. Is less likely to

As a preferred configuration, the filter portion is made of a plate material having a predetermined thickness, and the hole portion is penetrated through the plate material so as to be inclined with respect to the injection direction.
According to such a structure, a filter part can be provided also by providing a some hole part in a board | plate material.

  As a preferred configuration, the plate material is curved into a shape protruding into the battery case, and the hole is a flat surface of the plate material and has a perpendicular direction inclined with respect to the injection direction. Is provided.

  According to such a configuration, the hole portion having a penetrating direction inclined with respect to the injection direction can be formed in the plate material with a short length, so that the filter portion can be easily formed. Become.

  According to this secondary battery, it is possible to suppress the electrolytic solution from adhering to the injection port during manufacturing.

The perspective view which shows the general | schematic perspective structure about 1st Embodiment which actualized the secondary battery. The top view which shows the structure of the cover body of the secondary battery in the same embodiment, and the one part enlarged structure. Sectional drawing which shows the cross-sectional structure of the injection hole of the cover body in the 3-3 line of FIG. The end view which shows the expansion end surface structure of the injection inlet in the embodiment. Sectional drawing which shows the expanded sectional structure of the injection hole about 2nd Embodiment which actualized the secondary battery. The end view which shows the expansion end surface structure of the injection hole about 3rd Embodiment which actualized the secondary battery. The perspective view which shows the perspective structure of the injection port about other embodiment which actualized the secondary battery.

(First embodiment)
A first embodiment in which the secondary battery 10 is embodied will be described with reference to FIGS. The secondary battery 10 of this embodiment comprises an assembled battery by connecting two or more with a bus bar. The assembled battery is mounted on an electric vehicle or a hybrid vehicle, and supplies power to an electric motor or the like. The secondary battery 10 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and is a sealed battery having a rectangular parallelepiped shape.

  As shown in FIG. 1, the secondary battery 10 includes a rectangular parallelepiped battery case 11 having an opening, a lid body 12 that seals the battery case 11, and an electrode plate group 17 that is accommodated inside the battery case 11. And an electrolytic solution 75 (see FIG. 4). The battery case 11 and the lid 12 are made of a metal such as an aluminum member. That is, in the secondary battery 10, a sealed battery case is configured by attaching the lid 12 to the battery case 11. In addition, the secondary battery 10 has two external terminals 13 used for charging and discharging power, a safety valve 14, and an inlet for injecting an electrolyte into the battery case on the outer surface 2 a (see FIG. 2) of the lid 12. 15. In addition, the inlet 15 shown in FIG. 1 has shown the state by which the cover member 16 which seals opening of the inlet 15 is welded. The lid member 16 is also made of a metal such as an aluminum member.

FIG. 2 shows the inlet 15 before the lid member 16 is welded.
The injection port 15 is provided as a circular hole in the lid body 12. The first stage 5 a is recessed in a circular shape from the outer surface 2 a of the lid body 12. A second stage 5b that is recessed by one stage from the stage 5a, and a third stage 5c that is circular and recessed by one stage from the second stage 5b are provided inside the second stage 5b. The third stage 5c is the bottom of the injection port 15, but has a configuration through which the electrolytic solution can pass. The first stage 5a, the second stage 5b, and the third stage 5c are formed by scraping the outer surface 2a of the lid 12 or pressing the lid 12.

  As shown in FIG. 3, the first stage 5a is a portion where the lid member 16 is placed and welded. The second stage 5b is a portion into which the seal portion 7A of the electrolyte injection nozzle 7 is fitted when the electrolyte is injected into the battery case. The third stage 5 c is a thin plate-like part integrated with the lid body 12. The third stage 5c is a part where the thickness of the outer side surface 2a is reduced in the lid 12. In the third stage 5c, the injection part 7B of the injection nozzle 7 for electrolytic solution enters, and the electrolytic solution is injected from the injection part 7B. The third stage 5c includes a filter unit 50 that allows the electrolytic solution to pass therethrough and filter it.

  The filter unit 50 has a function of filtering the electrolyte solution injected from the injection nozzle 7. The filter unit 50 removes foreign substances having a predetermined size, for example, foreign substances larger than 100 micrometers (μm). That is, the filter unit 50 is configured to pass the electrolytic solution in the direction from the outer side surface 2a to the inner side surface 2b of the lid 12, but not to allow a predetermined size of foreign matter to pass through.

  As shown in FIG. 4, specifically, the filter unit 50 includes a plurality of holes 51. The plurality of holes 51 are formed in the third stage 5c by press molding. The third stage 5c is formed by press molding, and an upper stage 52 in which a part of the plate material is moved to the front side (the outer surface 2a side), and the other part is moved to the back side (the inner side 2b side). A lower stage 53 and a step between the upper stage 52 and the lower stage 53 are provided. And the hole 51 is formed when a part of level | step difference fractures | ruptures up and down. In addition, the aspect in which a torn surface is shape | molded in the shape which an electrolyte solution passes easily is good. The hole 51 maintains the shortest distance between the upper stage 52 and the lower stage 53, which is the shortest distance between the upper stage 52 and the lower stage 53. Here, the shortest separation distance is set to, for example, 100 μm or less, more preferably 100 μm or less and 70 μm or more.

  By the way, since the hole 51 is a portion broken in the vertical direction by press molding, the size of the opening is small when viewed from the front side which is the vertical direction, and the size of the opening is larger when viewed at an angle. appear. Here, the direction passing through the center of the hole 51 is defined as the penetration direction of the hole 51. At this time, the penetration direction 51c of the hole 51 is inclined with respect to the penetration direction of the injection port 15, that is, the direction in which the injection nozzle 7 injects the electrolytic solution 75 (injection direction). Further, the hole 51 has a relationship of “opening width a> opening width b” in which the opening width b when viewed from the injection direction appears to be smaller than the opening width a when viewed from the penetration direction 51c. Therefore, when the filter unit 50 is viewed from the injection direction, the apparent opening of the hole 51 is small in the opening width b, but when the electrolytic solution 75 flows into the step portion, the opening of the hole 51 has a substantial opening width a. It becomes a magnitude | size and the electrolyte solution 75 flows to the back side, without staying.

  The hole 51 can have an arbitrary length depending on the length of extension of the upper stage 52 and the lower stage 53, for example, it can be a slit shape, but it can be opened as the shortest distance at any position in the length direction. By maintaining the width a, it is possible to prevent a foreign substance having a size larger than at least the opening width a from passing.

  Further, the electrolytic solution 75 strikes the electrode plate group 17 immediately after passing through the filter unit 50 to cause rebound (liquid splash), or the liquid is temporarily accumulated in the electrode plate group 17 near the filter unit 50. It causes new. The liquid splash generated in the vicinity of the filter unit 50 may cause the splash of the liquid splash to pass through the hole 51 of the filter unit 50 and adhere to the injection port 15.

  By the way, in this embodiment, the opening of the hole 51 has a relationship of “opening width a> opening width b”. That is, even when the hole 51 is viewed from the inside of the battery case, the penetration direction 51c is inclined with respect to the anti-injection direction, which is the direction in which the electrolytic solution 75 flows down, and the apparent opening width. b is small. For this reason, the possibility that the splashed liquid in the battery case enters the opening having the opening width b is reduced, and the inclined hole portion 51 does not contact the wall surface of the hole portion 51 even if it enters the opening. The possibility of passing through is reduced. Therefore, the possibility that the splashed liquid in the battery case passes through the hole 51 outward and adheres to the injection port 15 is reduced.

  The opening width b is set to 25% or less and 2% or more of the opening width a, preferably 15% or less and 5% or more, more preferably 10% or less and 5% or more. . That is, when the opening width a is 100 μm or less and 70 μm or more, the opening width b is set in a range of 25 μm or less and 1.4 μm or more. Here, 25 μm is a value of 25% of 100 μm, and 1.4 μm is a value of 2% of 70 μm. Thereby, the suppression effect of the passage of the splash of liquid splash through the hole portion 51 and the suppression effect of the retention of the electrolytic solution on the upper portion of the filter portion 50 can both be achieved.

  When the electrolyte is injected, the seal portion 7A of the injection nozzle 7 is fitted into the second stage 5b. At this time, the electrolyte stays between the seal part 7A and the second stage 5b. Then, the staying electrolytic solution enters between the seal portion 7A and the second stage 5b and spreads to the second stage 5b. Therefore, the electrolytic solution adheres to the portion where the second stage 5b is adjacent to the first stage 5a.

  Further, when an amount of electrolyte more than the amount that can be accommodated between the seal portion 7A and the second stage 5b enters, excess electrolyte oozes out around the injection nozzle 7 and reaches the first stage 5a. May spread. That is, the electrolytic solution adheres to the first stage 5a, which is a portion to which the lid member 16 is welded.

  Therefore, the adhesion of the electrolytic solution 75, which causes the poor welding of the lid member 16 that seals the injection port 15, to the injection port 15, particularly the first step 5a, and the first step of the second step 5b. It is necessary to reduce the adhesion to the portion close to the eye 5a. Therefore, even if the electrolytic solution splashes in the battery case even if it is splashed, the risk of adhering to the injection nozzle 7 or the injection port 15 is reduced, thereby reducing the welding failure of the lid member 16 to the injection port 15. Will come to be.

As described above, according to the secondary battery 10 of the present embodiment, the following effects can be obtained.
(1) In the injection direction of the electrolytic solution 75, that is, the direction in which the electrolytic solution 75 flows down, the penetration direction of the hole 51 has an inclination with respect to the injection direction, and the apparent opening becomes small. The risk of splashing the splashed electrolytic solution 75 passing through the hole 51 and adhering to the injection port 15 is reduced. And since the electrolyte solution 75 is filtered by the hole 51 of the filter part 50 on that, mixing of the foreign material into a battery case is suppressed, and generation | occurrence | production of the problem etc. which arise in a battery by mixing of a foreign material is suppressed. It becomes like.

(2) It is possible to achieve both the effect of suppressing the passage of the splash of liquid splash through the hole 51 and the effect of suppressing the retention of the electrolytic solution 75 with respect to the upper portion of the filter unit 50.
(3) The possibility that the nonaqueous electrolyte may cause poor welding of the lid member 16 to the inlet 15 is reduced.

(4) Since the intrusion of foreign matter larger than 100 μm is prevented by the filter unit 50, the possibility of such foreign matter short-circuiting the electrode plate group and the outer wall of the battery case is reduced.
(5) By using different plate materials, that is, the upper stage 52 and the lower stage 53, it is possible to provide the hole 51 having a larger opening in the penetration direction than the opening size in the injection direction. The hole 51 can be formed by, for example, shearing a plate material at a step portion by press forming a step.

(Second Embodiment)
A second embodiment in which the secondary battery 10 is embodied will be described with reference to FIG. In the present embodiment, the configuration of the filter unit 60 is different from that of the first embodiment. Therefore, in the following, the configuration that is mainly different from the first embodiment will be described in detail, and for convenience of description, the same reference numerals are given to the same configuration and the detailed description is omitted.

  As shown in FIG. 5, the injection port 15 includes a first stage 5a, a second stage 5b, and a third stage 5c which is a bottomed cylindrical body extending from the second stage 5b into the battery case. With. The third stage 5 c has a cylindrical side surface 61 and a bottom 63. The third stage 5c is provided with a filter unit 60 for filtering the electrolytic solution.

  The filter unit 60 includes a plurality of slit-shaped holes 62 extending in the injection direction on the peripheral side surface 61 of the cylindrical body of the third stage 5c. The slit-shaped hole 62 removes foreign matters larger than about 100 μm. The slit-shaped hole 62 removes foreign matters larger than a predetermined size, here 100 μm, with the width of the slit as the shortest separation distance.

  By the way, the slit-shaped hole 62 is a portion opened on the peripheral side surface of the cylindrical body extending in the injection direction. It can be seen in the maximum size when viewed from the direction. In addition, the slit-like hole 62 is inclined in the penetrating direction with respect to the injection direction. That is, the slit-shaped hole 62 has a relationship of “opening width a> opening width b” in which the opening width b when viewed in the injection direction appears to be smaller than the opening width a when viewed in the penetration direction. . Further, the bottom 63 is not provided with a hole.

Therefore, the slit-shaped hole portion 62 suppresses the outward passage of the splashed electrolyte solution in the battery case, and reduces the possibility of the electrolyte solution adhering to the injection port 15.
In addition, when the filter unit 60 is viewed from the injection direction, although the opening of the slit-shaped hole 62 is small, the opening of the slit-shaped hole 62 is substantially large because the electrolytic solution 75 flows into the cylindrical body. Thus, the electrolytic solution 75 can flow to the back side without staying.

As described above, the secondary battery 10 of the present embodiment has the following effects in addition to the effects (1) to (4) described in the first embodiment.
(6) Since the penetrating direction of the slit-shaped hole 62 is orthogonal or nearly orthogonal to the injection direction, the splashed electrolyte solution passes through the slit-shaped hole 62 in the battery case. The possibility of adhering to the inlet 15 is small.

(Third embodiment)
A third embodiment in which the secondary battery 10 is embodied will be described with reference to FIG. In the present embodiment, the configuration of the filter unit 70 is different from that of the first embodiment. Therefore, in the following, a configuration that is mainly different from the first embodiment will be described in detail.

  FIG. 6 shows the filter unit 70. The filter unit 70 is provided in the third stage 5 c of the inlet 15. In this embodiment, the 3rd step | paragraph 5c is the board 71 as a board | plate material which has predetermined | prescribed board thickness, and is carrying out the curved shape which makes a center part protrude most in a battery case.

  The filter unit 70 has a plurality of holes 72 in a curved plate 71. The hole 72 is formed to penetrate the plate 71, and the penetration direction is inclined with respect to the injection direction. The hole 72 is provided at a position excluding the most protruding portion in the battery case of the plate 71 and the vicinity thereof. That is, the hole part 72 is provided in the plane part which has the perpendicular direction which inclines with respect to the injection | pouring direction among the plate bodies 71. FIG.

  By the way, since the plate body 71 is curved, the angle formed between the perpendicular direction and the injection direction is small in the portion protruding into the battery case, and the perpendicular direction and the injection become closer to the outer periphery of the plate body 71. The angle made with the direction increases. Therefore, by forming the hole 72 in the plate 71 so as to shorten the length, the penetration direction of the hole 72 is naturally inclined with respect to the injection direction.

  Also in this embodiment, since the penetration direction of the hole 72 is inclined in the injection direction, the opening width b when the hole 72 is viewed in the injection direction can be smaller than the opening width a when the hole 72 is viewed in the penetration direction. In addition, by not providing the most protruding part in the battery case and the vicinity thereof, the distance from the hole 72 to the liquid splashing part in the battery case is secured widely, and splashes due to liquid splashing in the battery case are generated. Adhesion to the inlet 15 can be suppressed. Furthermore, by making the plate 71 have a curved shape protruding into the battery case, the electrolyte can easily flow into the battery case.

As described above, the secondary battery 10 of the present embodiment has the following effects in addition to the effects (1) to (4) described in the first embodiment.
(7) The filter part 70 can also be provided by providing a plurality of hole parts 72 in the plate 71.

(8) Since the hole portion 72 having the penetrating direction inclined with respect to the injection direction can be formed in the plate body 71 with a short length, the filter portion 70 can be easily formed.
(Other embodiments)
-In the said 3rd Embodiment, it illustrated about the case where it provided in the position except the part which protruded most in the battery case of the plate 71, and its vicinity. However, the present invention is not limited to this, and the hole may be provided in the portion of the plate that protrudes most into the battery case or in the vicinity thereof, as long as the penetrating direction is inclined in the injection direction.

  In the second embodiment, the case where the slit-shaped hole 62 is provided in the peripheral side surface 61 of the cylindrical body is illustrated. However, the present invention is not limited to this, and the structure of the hole provided on the peripheral side surface of the cylindrical body is any structure as long as it can remove foreign matter from the electrolytic solution and suppress the splashing of the electrolytic solution. May be.

  For example, as shown in FIG. 7, you may provide the filter part 80 which has the net | network 84 which filters electrolyte solution on the surrounding side surface 82 of the bottomed cylindrical body (3rd step | paragraph) extended in a battery case. The mesh 84 includes eyes as a plurality of holes, and the size of each of the meshes is a size capable of removing foreign matters larger than 100 μm. Note that no holes are formed in the bottom 83. Therefore, the opening width b seen in the injection direction is “0”, and the relationship of opening width a> opening width b is maintained with the opening width a seen in the penetration direction.

The filter unit 80 may be integrated with the lid 12 or may be separate.
In the case of a separate body, the filter unit 80 may be provided with a flange 81 that contacts the second stage 5 b of the injection port 15, and may be assembled from the outer surface 2 a of the lid 12. At this time, if the thickness of the flange 81 is made lower than the step between the first step 5a and the second step 5b, the injection nozzle 7 can be connected via the injection port 15 in the same manner as the above embodiment. An electrolyte can be injected.

  -In the said 2nd Embodiment, although illustrated about the case where the slit was formed in the vertical direction, it is not restricted to this, The direction in which a slit is formed may be a horizontal direction or a diagonal direction, and the vertical and horizontal diagonal Two or more directions may be combined.

  -In the said 2nd Embodiment and other embodiment, although illustrated about the case where the hole is not provided in the bottom parts 63 and 83, it is not restricted to this, Even if some holes are provided in the bottom part Good. It is further preferable that the penetration direction has an inclination with respect to the injection direction so that the passage of the electrolytic solution splashed can be suppressed.

  -In the said 1st Embodiment, although illustrated about the case where the level | step difference fractured | ruptured by the press was formed, it is not restricted to this, While a penetration direction inclines with respect to a distribution direction, it has an opening of suitable magnitude | size. As long as a hole is provided, the hole may be provided in any manner.

  In each of the above embodiments, the case where the hole portion has the shortest separation distance of 100 μm or less and 70 μm or more is illustrated, but the invention is not limited thereto, and the shortest hole portion depends on the size of the foreign matter that needs to be removed. May be narrower than 70 μm, or conversely, wider than 100 μm.

  In each of the above embodiments, the case where the secondary battery 10 is composed of a lithium ion secondary battery is illustrated, but the present invention is not limited thereto, and other secondary batteries such as a nickel hydride secondary battery may be used. Good.

  In each of the above embodiments, the case where the secondary battery 10 is mounted on an electric vehicle or a hybrid vehicle is illustrated. However, the present invention is not limited to this, and the secondary battery is other than an electric vehicle or a hybrid vehicle such as a gasoline vehicle or a diesel vehicle. It may be mounted on other vehicles. The secondary battery may be used as a power source for a mobile body other than an automobile or a power source fixedly installed. For example, power sources other than automobiles include moving bodies such as railroads, ships, airplanes, and robots, and power supplies for electrical products such as information processing apparatuses.

  2a ... outer surface, 2b ... inner surface, 5a ... first stage, 5b ... second stage, 5c ... third stage, 7 ... injection nozzle, 7A ... seal part, 7B ... injection part, 10 ... two Secondary battery, 11 ... Battery case, 12 ... Lid, 13 ... External terminal, 14 ... Safety valve, 15 ... Inlet, 16 ... Lid member, 17 ... Electrode plate group, 50 ... Filter part, 51 ... Hole part, 51c ... Through direction, 52 ... upper stage, 53 ... lower stage, 60 ... filter part, 61 ... peripheral side surface, 62 ... hole part, 63 ... bottom part, 70 ... filter part, 71 ... plate body, 72 ... hole part, 75 ... electrolyte, 80 ... Filter part, 81 ... Flange, 82 ... Circumferential side surface, 83 ... Bottom part, 84 ... Net.

Claims (8)

A secondary battery in which a power generation element is housed in a battery case composed of a case and a lid,
An inlet provided in the lid and into which an electrolyte is injected;
A filter portion provided at the inlet and for circulating an electrolyte supplied from outside the battery case;
The filter part has a plurality of holes that penetrate from the outside to the inside of the battery case,
Each of the holes has a direction through which the hole is inclined with respect to the direction in which the electrolyte is injected, and is viewed from the direction of penetration than the size of the opening viewed from the direction of injection. A secondary battery having a larger opening size. The secondary battery according to claim 1, wherein the size of the opening viewed from the injection direction is 25% or less and 2% or more of the size of the opening viewed from the penetrating direction. The secondary battery according to claim 1, wherein the electrolytic solution contains a nonaqueous electrolyte. The secondary battery according to any one of claims 1 to 3, wherein the opening of the hole portion viewed from the penetrating direction has a shortest opening distance set to 100 micrometers or less. The filter portion is made of a plate material, and a plurality of steps are formed in the injection direction at a plurality of locations of the plate material,
The secondary battery according to claim 1, wherein the hole is formed in the stepped portion. The filter portion is a bottomed cylindrical body extending from the inlet into the battery case,
The secondary battery according to claim 1, wherein the hole is provided on a peripheral side surface of the cylindrical body. The filter portion is made of a plate material having a predetermined thickness,
The secondary battery according to any one of claims 1 to 4, wherein the hole portion is penetrated through the plate member so as to have an inclination with respect to the injection direction. The plate material is curved into a shape protruding into the battery case,
The secondary battery according to claim 7, wherein the hole is provided in a portion that is a flat surface of the plate member and has a perpendicular direction inclined with respect to the injection direction.