JP2018049802A - Power storage device - Google Patents

Abstract

Provided is a power storage device that can make the temperature distribution of a stacked body of bipolar electrodes uniform. A power storage device (1) having a bipolar electrode (3) comprising an electrode plate (11) having a positive electrode (12) formed on one surface (11a) side and a negative electrode (13) formed on the other surface (11b) side. A laminated body 2 formed by laminating the electrodes 3 and an insulating frame 4 surrounding and holding the side surface 2a of the laminated body 2 formed by laminating the bipolar electrodes 3 are provided. , Decreases from the end in the laminating direction of the laminate 2 toward the center. [Selection diagram] Fig. 1

Description

  The present invention relates to a power storage device.

  As a conventional power storage device, a bipolar battery including a bipolar electrode in which a positive electrode is formed on one surface of an electrode plate and a negative electrode is formed on the other surface is known (see Patent Document 1). The bipolar battery is provided with a laminate formed by laminating a plurality of bipolar electrodes via a separator. The laminated body is provided with an insulating frame for sealing, and the side surface formed by the lamination of the bipolar electrodes is held.

JP 2011-151016 A

  In the power storage device as described above, since the frame body is provided on the side surface of the stacked body, there is a problem that the heat dissipation performance of the central portion in the stacking direction of the stacked body is inferior to the heat dissipation performance of the end portions. For this reason, if the bipolar electrode generates heat when the power storage device is used, heat is likely to be generated in the central portion in the stacking direction of the stacked body, resulting in non-uniform temperature distribution of the stacked body. There is a possibility that the deterioration proceeds more than the deterioration of the bipolar electrode at the end.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power storage device that can make the temperature distribution of a laminate of bipolar electrodes uniform.

  A power storage device according to one aspect of the present invention is a power storage device having a bipolar electrode made of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side, the bipolar electrode being interposed via a separator And an insulating frame that surrounds and holds the side surface of the stacked body formed by stacking bipolar electrodes, and the thickness of the frame is the end in the stacking direction of the stacked body It decreases from the part side toward the center part side.

  In this power storage device, in the frame body that surrounds and holds the side surface of the multilayer body, the thickness of the frame body decreases from the end side in the stacking direction of the bipolar electrode multilayer body toward the center side. Thereby, in the center part of the lamination direction of a frame, heat dissipation becomes high compared with an edge part, and it can suppress that a heat | fever gets into the center part of the lamination direction in a laminated body. Accordingly, the temperature distribution of the bipolar electrode stack can be made uniform.

  Further, the thickness of the frame body may decrease from the end portion side of the side surface of the laminated body toward the central portion side when viewed from the lamination direction of the laminated body. In the laminated body of bipolar electrodes, when viewed from the stacking direction, heat tends to be easily generated at the central portion in the in-plane direction. Therefore, when viewed from the stacking direction of the stacked body, the thickness of the frame body decreases from the end side of the side surface of the stacked body toward the center side, so that the center of the stacked body in the in-plane direction is reduced. It is possible to suppress the heat from burning. As a result, the temperature distribution of the laminated body of bipolar electrodes can be more preferably uniformized.

  The power storage device may include a pair of restraint plates arranged so as to sandwich the stack in the stacking direction, and a connecting member that connects the pair of restraint plates and applies a restraining load to the stack. . With such a configuration, an appropriate restraining pressure can be applied to the laminate and the frame body 4 by the restraining plate.

  The power storage device includes a pair of current collector plates disposed between the restraint plate and the laminate so as to sandwich the laminate in the stacking direction, and the current collector plate and the restraint plate are interposed via an insulating member. It may be combined. In this case, the restraint plate and the current collector plate can be integrated, and the configuration around the terminals connected to the laminate can be simplified.

  According to the present invention, the temperature distribution of the laminated body of bipolar electrodes can be made uniform.

It is a schematic sectional drawing which shows the structure of the electrical storage apparatus which concerns on one Embodiment of this invention. It is a simulation result which shows the temperature distribution of the laminated body at the time of use. It is a schematic sectional drawing which shows the shape of the frame seen from the lamination direction of the laminated body. It is a schematic sectional drawing which shows the structure of the electrical storage apparatus which concerns on a modification. It is a schematic sectional drawing which shows the structure of the electrical storage apparatus which concerns on another modification.

  Hereinafter, preferred embodiments of a power storage device according to one aspect of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view illustrating a configuration of a power storage device according to an embodiment of the present invention. The power storage device 1 shown in the figure is a bipolar battery including a laminated body 2 of bipolar electrodes 3. The power storage device 1 is, for example, a secondary battery such as a nickel metal hydride secondary battery or a lithium ion secondary battery, or an electric double layer capacitor. The power storage device 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. In the following description, a nickel metal hydride secondary battery is illustrated.

  The power storage device 1 includes the laminate 2 of the bipolar electrode 3 described above, a frame 4 that holds the laminate 2, and a restraining member 5 that restrains the laminate 2.

  The laminate 2 is configured by laminating a plurality of bipolar electrodes 3 with separators 6 interposed therebetween. Each of the bipolar electrodes 3 includes an electrode plate 11, a positive electrode 12 provided on one surface 11 a of the electrode plate 11, and a negative electrode 13 provided on the other surface 11 b of the electrode plate 11. In the stacked body 2, the positive electrode 12 of one bipolar electrode 3 faces the negative electrode 13 of one bipolar electrode 3 adjacent in the stacking direction across the separator 6, and the negative electrode 13 of one bipolar electrode 3 It faces the positive electrode 12 of the other bipolar electrode adjacent in the stacking direction.

  The electrode plate 11 is a metal foil made of nickel, for example. The thickness of the electrode plate 11 is, for example, about 0.1 μm to 1000 μm. An example of the positive electrode active material constituting the positive electrode 12 is nickel hydroxide. An example of the negative electrode active material constituting the negative electrode 13 is a hydrogen storage alloy. The formation region of the negative electrode 13 on the other surface 11 b of the electrode plate 11 may be slightly larger than the formation region of the positive electrode 12 on the one surface 11 a of the electrode plate 11.

  The edge portion 11 c of the electrode plate 11 is an uncoated region where the positive electrode active material and the negative electrode active material are not applied, and is held by the frame body 4 while being embedded in the inner wall 4 a of the frame body 4. Thereby, a space partitioned by the electrode plates 11 and 11 and the inner wall 4a of the frame body 4 is formed between the electrode plates 11 and 11 adjacent in the stacking direction. In the space, an electrolytic solution (not shown) made of an alkaline solution such as an aqueous potassium hydroxide solution is accommodated.

  An electrode plate 11A in which only the negative electrode 13 is provided on one side is laminated on one laminated end of the laminated body 2 (upper laminated end in FIG. 1). The electrode plate 11A is arranged so that the negative electrode 13 and the positive electrode 12 of the uppermost bipolar electrode 3 face each other with the separator 6 interposed therebetween. In addition, an electrode plate 11B provided with only the positive electrode 12 is stacked on the other stacked end of the stacked body 2 (lower stacked end in FIG. 1). The electrode plate 11B is arranged so that the positive electrode 12 and the negative electrode 13 of the lowermost bipolar electrode 3 face each other with the separator 6 interposed therebetween. The edge portions of the electrode plates 11 </ b> A and 11 </ b> B are held by the frame body 4 in a state of being buried in the inner wall 4 a of the frame body 4, similarly to the electrode plate 11 of the bipolar electrode 3. The electrode plates 11A and 11B may be formed thicker than the electrode plate 11 of the bipolar electrode 3.

  The separator 6 is formed in a sheet shape, for example. Examples of the material for forming the separator include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose and the like. The separator 6 may be reinforced with a vinylidene fluoride resin compound. The separator 6 is not limited to a sheet shape, and may be a bag shape.

  The frame 4 is formed in a rectangular cylindrical shape by, for example, injection molding using an insulating resin. Examples of the resin material constituting the frame 4 include polypropylene (PP), polyphenylene sulfide (PPS), and modified polyphenylene ether (modified PPE). The frame body 4 is a member that surrounds and holds the side surface 2 a of the multilayer body 2 formed by the lamination of the bipolar electrodes 3. More specifically, the frame 4 holds the edge of the electrode plate 11 of the bipolar electrode 3 and the electrode plates 11A and 11B located at the stacking end of the stack 2, and is formed between the bipolar electrodes 3 and 3. The electrolytic solution storage space is sealed.

  The restraining member 5 includes a pair of restraining plates 21 and 21 and connecting members (bolts 22 and nuts 23) that join the restraining plates 21 and 21 together. The restraint plate 21 is formed in a flat plate shape with a metal such as iron. An insertion hole 21 a through which the bolt 22 is inserted is provided at a position on the outer side of the frame body 4 at the edge of the restraint plate 21. Further, a current collecting plate 25 (25A, 25B) is coupled to one surface side of the restraining plate 21 via an insulating member 24. Thereby, the restraining plate 21 is a restraining plate with a current collecting plate that serves both as a restraining function and a current collecting function. Examples of the material for forming the insulating member 24 interposed between the restraint plate 21 and the current collector plate 25 include urethane resin, epoxy resin, polypropylene, PA66, and the like.

  One restraint plate 21 is abutted against one end surface of the frame body 4 so that the current collector plate 25 </ b> A and the electrode plate 11 </ b> A are in contact with each other inside the frame body 4, and the other restraint plate 21 is disposed inside the frame body 4. The current collector plate 25B and the electrode plate 11B are abutted against the other end surface of the frame body 4 so as to contact each other. For example, the bolt 22 is passed through the insertion hole 21a from one restraint plate 21 side to the other restraint plate 21 side, and a nut 23 is screwed onto the tip of the bolt 22 protruding from the other restraint plate 21. Yes.

  Thereby, the laminate 2, the electrode plates 11A and 11B, and the frame 4 are sandwiched and unitized, and a restraining load is applied. Further, the current collector plates 25A and 25B are disposed between the constraining plate 21 and the stacked body 2 so as to sandwich the stacked body 2 in the stacking direction. A positive electrode terminal 26 is connected to the current collector plate 25A, and a negative electrode terminal 27 is connected to the current collector plate 25B. The power storage device 1 can be charged and discharged by the positive electrode terminal 26 and the negative electrode terminal 27.

  Next, the configuration of the frame 4 in the above-described power storage device 1 will be described in more detail.

  In the power storage device in which the frame is provided so as to surround the side surface of the bipolar electrode laminate, there is a problem that the heat dissipation at the center in the stacking direction of the laminate is inferior to the heat dissipation at the end. FIG. 2 is a simulation result showing the temperature distribution of the laminate during use. As can be seen from the results shown in the figure, when the bipolar electrode generates heat when the power storage device is used, it can be confirmed that the heat tends to flow in the central portion of the stacked body in the stacking direction.

  This also applies to the in-plane direction of the laminate (in-plane direction of the electrode plate). From the results shown in FIG. 2, it is confirmed that the heat tends to heat in the center when the laminate is viewed from the laminate direction. it can. As a result of such a thermal bias, the temperature distribution of the laminated body becomes non-uniform, and as a result, the deterioration of the bipolar electrode at the center of the laminated body may proceed as compared with the deterioration of the bipolar electrode at the end.

  On the other hand, in the power storage device 1, as shown in FIG. 1, the thickness of the frame body 4 decreases from the end side in the stacking direction of the stacked body 2 toward the central portion side. More specifically, the outer wall 4b of the frame body 4 has a concave portion V whose wall surface gently curves into a concave shape corresponding to the length in the stacking direction of the stacked body 2 (the length of the arrangement position of the bipolar electrode 3). Is provided. Due to the formation of the recesses V, the thickness of the frame body 4 is the thinnest at a position corresponding to the central portion of the stacked body 2 in the stacking direction. The concave portion V does not extend to both end portions of the frame body 4 in the stacking direction of the multilayer body 2, and the portions corresponding to the electrode plates 11A and 11B and the current collector plates 25A and 25B are portions where the concave portion V is formed. It is thicker than

  Further, in the present embodiment, due to the formation of the concave portion V, as shown in FIG. 3, even when viewed from the stacking direction of the stacked body 2, the thickness of the frame body 4 is the end side of the side surface 2 a of the stacked body 2. It decreases from the (corner 4c side) toward the center side. That is, the thickness of the frame body 4 is the thinnest at a position corresponding to each central portion of the four sides of the frame body 4. The recess V does not extend to the corner 4c of the frame body 4, and the corner 4c is thicker than the portion where the recess V is formed.

  As described above, in the power storage device 1, the recess V is formed in the frame 4 that surrounds and holds the side surface 2 a of the stacked body 2, and the thickness of the frame 4 is the stacking direction of the stacked body 2 of the bipolar electrode 3. It decreases from the end side toward the center side. Thereby, in the center part of the lamination direction of the frame 4, heat dissipation becomes high compared with an edge part, and it can suppress that a heat | fever gets into the center part of the lamination direction in the laminated body 2. FIG. Therefore, the temperature distribution of the laminate 2 of the bipolar electrode 3 can be made uniform.

  Further, in the power storage device 1, due to the formation of the recess V, the thickness of the frame 4 decreases from the end side of the side surface 2 a of the stacked body 2 toward the central portion when viewed from the stacking direction of the stacked body 2. ing. Thereby, it can suppress that a heat | fever heats at the center part of the in-plane direction in the laminated body 2. FIG. Therefore, the temperature distribution of the laminated body 2 of the bipolar electrode 3 can be more preferably uniformized.

  The power storage device 1 includes a pair of restraining plates 21 and 21 arranged so as to sandwich the laminate 2 in the laminating direction, and a connection that applies a restraining load to the laminate 2 by connecting the pair of restraining plates 21 and 21. Members (bolts 22 and nuts 23). With such a configuration, appropriate restraint pressure can be applied to the laminate 2 and the frame body 4 by the restraint plate 21.

  The power storage device 1 further includes a pair of current collector plates 25A and 25B disposed between the restraint plate 21 and the laminate 2 so as to sandwich the laminate 2 in the stacking direction, and restrains the current collector plates 25A and 25B. The plate 21 is coupled via an insulating member 24. With such a configuration, the restraint plate 21 and the current collector plate 25 can be integrated, and the configuration around the positive electrode terminal 26 and the negative electrode terminal 27 connected to the laminate 2 can be simplified.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the thickness of the frame body 4 is reduced by the concave portion V having a gently curved wall surface. However, as shown in FIG. 4, for example, the frame body 4 is formed by the concave portion Va having a flat wall surface. For example, as shown in FIG. 5, the thickness of the frame body 4 may be reduced by a recess Vb whose wall surface forms a step shape. Even when such a recess is employed, the temperature distribution of the laminate 2 of bipolar electrodes 3 can be made uniform.

  Moreover, in the said embodiment, although the recessed part V is provided in all four surfaces of the outer wall 4b in the frame 4 (refer FIG. 3), the structure which provides the recessed part V only in two surfaces of the outer wall 4b which mutually opposes in a frame. It is good.

  DESCRIPTION OF SYMBOLS 1 ... Power storage device, 2 ... Laminated body, 2a ... Side surface, 3 ... Bipolar electrode, 4 ... Frame, 6 ... Separator, 11 ... Electrode plate, 11a ... One side, 11b ... Other side, 12 ... Positive electrode, 13 ... Negative electrode , 21 ... restraint plate, 22 ... bolt (connection member), 23 ... nut (connection member), 24 ... insulating member, 25 (25A, 25B) ... current collector plate.

Claims (4)

A power storage device having a bipolar electrode made of an electrode plate having a positive electrode formed on one side and a negative electrode formed on the other side,
A laminate formed by laminating the bipolar electrode via a separator;
An insulating frame that surrounds and holds a side surface of the laminate formed by the lamination of the bipolar electrodes,
The thickness of the said frame is an electrical storage apparatus which is decreasing toward the center part side from the edge part side of the lamination direction of the said laminated body.   2. The power storage device according to claim 1, wherein the thickness of the frame body decreases from an end portion side of the side surface of the stacked body toward a central portion side when viewed from the stacking direction of the stacked body. A pair of constraining plates arranged to sandwich the laminate in the laminating direction;
The power storage device according to claim 1, further comprising: a connecting member that connects the pair of restraining plates and applies a restraining load to the stacked body. A pair of current collector plates disposed between the constraining plate and the laminate so as to sandwich the laminate in the laminating direction;
The power storage device according to claim 3, wherein the current collecting plate and the restraining plate are coupled via an insulating member.