JP5609905B2 - Power storage device, secondary battery and vehicle - Google Patents

Description

  This specification discloses a technology relating to a power storage device and a vehicle equipped with the power storage device. In particular, a technique related to a secondary battery including the power storage device is disclosed.

  In the technical field of power storage devices, development of current interrupting devices that cut off the current flowing between the terminals when the power storage device is overcharged or when a short circuit occurs internally is underway. In Patent Literature 1, a current interrupting device is provided between the negative electrode and the negative electrode terminal to interrupt conduction between the negative electrode and the negative electrode terminal when the internal pressure in the case increases.

JP 2000-1113912 A

  In the technical field of power storage devices, there is a demand to increase the power storage capacity without increasing the size. In order to increase the storage capacity, the size of the electrode structure (positive electrode and negative electrode) may be increased. However, when a current interruption device is provided between the negative electrode and the negative electrode terminal as in Patent Document 1, if the electrode structure size is increased, the electrode structure and the current interruption device come into contact with each other, and the positive electrode and the negative electrode are short-circuited. There are things to do. More specifically, during normal use, the positive electrode and the current interrupt device may come into contact with each other, causing a short circuit. In order to avoid a situation where the positive electrode contacts the current interrupting device, it is necessary to provide a sufficient gap between the electrode structure and the current interrupting device. Therefore, in the technique of Patent Document 1, the size of the electrode structure cannot be increased, and the storage capacity cannot be increased. The present specification provides a technique for increasing the storage capacity of a power storage device.

The power storage device disclosed in this specification includes a case, an electrode structure, a positive electrode lead, a negative electrode lead terminal, and a current interrupt device. The electrode structure is housed in the case and includes a positive electrode and a negative electrode. The positive electrode lead is electrically connected to the positive electrode. The negative electrode lead is electrically connected to the negative electrode. The current interrupting device is accommodated in the case and connected to at least one of the positive electrode lead and the negative electrode lead. The current interrupt device switches from the conductive state to the non-conductive state according to the internal pressure in the case. In this power storage device, the current interrupting device is disposed between the electrode structure and the inner surface of the case. The current interrupting device includes a diaphragm having a protruding portion formed at a central portion, and a fracture plate in which a tip portion of the protruding portion is fixed and a groove portion surrounding the portion where the tip portion is fixed is formed. In the power storage device disclosed in this specification , an insulating film is provided on the surface of the portion of the fracture plate that directly faces the electrode structure and faces the diaphragm .

  According to the above power storage device, since the insulating film is provided on the surface of the current interrupting device on the electrode structure side, even if the electrode structure contacts the current interrupting device, it is difficult for a short circuit to occur. Therefore, it is not necessary to provide a large gap between the electrode structure and the current interrupt device. Since the size of the electrode structure can be increased, the storage capacity of the power storage device can be increased.

  According to the technology disclosed in this specification, the power storage capacity of the power storage device can be increased.

A cross-sectional view of a power storage device is shown. The current interruption device when the terminal and the electrode are conducting is shown. The electric current interruption apparatus when a terminal and an electrode are non-conducting is shown.

  Hereinafter, some technical features of the embodiments disclosed in this specification will be described. The items described below have technical usefulness independently.

(Feature 1)
The power storage device includes a case, an electrode structure, a positive electrode lead, a negative electrode lead terminal, and a current interrupt device. The electrode structure is housed in the case and may include a positive electrode and a negative electrode. The positive electrode lead is electrically connected to the positive electrode. The negative electrode lead is electrically connected to the negative electrode. The current interrupt device may be housed in the case and connected to at least one of the positive electrode lead and the negative electrode lead. The current interrupt device may be of a type that switches from a conductive state to a non-conductive state according to the internal pressure in the case. The electric current interruption apparatus may be arrange | positioned between the electrode structure and the inner surface of the case. In the current interrupt device, an insulating film may be provided on the surface on the electrode structure side.

(Feature 2)
A positive electrode terminal that is exposed to the outside of the case from one side of the case and connected to the positive electrode lead, and a negative electrode terminal that is exposed to the outside of the case from one side of the case and connected to the negative electrode lead. You may have. That is, both the positive terminal and the negative terminal may be arranged in one direction of the case. The electric current interruption apparatus may be arrange | positioned between the electrode structure and one surface of the case.

(Feature 3)
The current interrupt device may be of a type including a diaphragm and a break plate. The diaphragm may have a protrusion at the center. In addition, the break plate may have a groove portion surrounding a portion where the tip portion of the diaphragm is fixed and the tip portion of the diaphragm is fixed. The insulating film may be formed on the surface of the fractured plate on the electrode structure side. When the groove portion of the breaking plate breaks, the central portion of the diaphragm moves in a direction away from the breaking plate. When the internal pressure in the case rises, the current can be cut off more reliably.

(Feature 4)
In the current interrupt device, in addition to the above-described insulating film, a second insulating film may be provided on the inner surface side of the case. When the material of the case is a conductive material, when the current interrupting device and the case come into contact, a current may flow between the current interrupting device and the case. By providing the second insulating film, it is possible to prevent a current from flowing between the current interrupting device and the case even if the material of the case is a conductive material. Since the current interrupt device and the case can be reliably insulated, it is not necessary to provide a large gap between the current interrupt device and the case. As a result, the current interrupt device can be brought close to the case. Since the distance between the current interrupting device and the electrode structure can be made closer by the amount that the gap between the current interrupting device and the case is omitted, the size of the electrode structure can be increased.

(Feature 5)
The insulating film described above may be a coating film. The term “insulating film” as used herein refers to an insulating film provided on the surface of the current interrupting device on the electrode structure side and an insulating film provided on the inner surface of the case of the current interrupting device (second insulating film). Means at least one of (film). The coating film can be uniformly and thinly formed on the surface of the current interrupt device. An example of the material for the coating film is a curable resin.

(Feature 6)
The electrode structure may include a convex portion that protrudes toward the inner surface side of the case. In general, the electrodes (positive electrode and negative electrode) constituting the electrode structure include a current collecting tab for collecting current. It is necessary to secure a space for arranging the current collecting tab between the electrode structure and the case. In the range where the current collecting tab is not disposed, the gap between the electrode structure and the case can be made smaller than the portion where the current collecting tab is disposed. Therefore, the convex part which protrudes in a case side can be formed in an electrode structure. The size of the electrode structure is increased by the amount of the protrusions, and the capacity of the power storage device is increased. In this case, it is preferable that the electric current interruption apparatus is arrange | positioned between the convex part of an electrode structure, and the inner surface of a case. In the power storage device disclosed in this specification, since a short circuit between the current interrupt device and the electrode structure is prevented, the current interrupt device can be disposed between the convex portion and the inner surface of the case.

  The power storage device disclosed in this specification has a large battery capacity while being compact. This power storage device is mounted on a vehicle, for example, and can supply electric power to the motor. Hereinafter, embodiments disclosed in the present specification will be described in detail.

(Power storage device)
Examples of the power storage device include a secondary battery and a capacitor. As an example of a secondary battery, a stacked type secondary battery in which a plurality of cells having electrode pairs (positive electrode and negative electrode) facing each other with a separator interposed therebetween, and a sheet-like shape having an electrode pair facing each other via a separator A wound type secondary battery in which the cells are processed into a spiral shape can be mentioned. In the following description, a power storage device in which both the positive electrode terminal and the negative electrode terminal are exposed in one direction of the case will be described. However, the technique disclosed in this specification is a state in which the case functions as a terminal of one polarity (for example, a negative electrode) and the terminal of the other polarity (for example, the positive electrode) is insulated from the case as in a cylindrical battery. It can also be applied to a power storage device of the type fixed to the case.

  The structure of the power storage device will be described with reference to FIG. The power storage device 100 includes a case 4, an electrode structure 2, a positive electrode terminal 30, a negative electrode terminal 10, and a current interrupt device 50. The case 4 is made of metal and has a substantially rectangular parallelepiped shape. Inside the case 4, the electrode structure 2 and the current interrupt device 50 are accommodated. Further, the inside of the case 4 is filled with an electrolytic solution. The positive electrode terminal 30 and the negative electrode terminal 10 are exposed to the outside of the case 4 on a surface in one direction of the case 4 (hereinafter referred to as an upper surface 4 a). In other words, the positive electrode terminal 30 and the negative electrode terminal 10 are arranged in the same direction. Through holes 4 b and 4 c are formed in the upper surface 4 a of the case 4. The positive electrode terminal 30 passes through the through hole 4b, and the negative electrode terminal 10 passes through the through hole 4c. An insulating first seal member 42 is attached to the through hole 4b. An insulating second seal member 22 is attached to the through hole 4c. Note that the shape of the case 4 is not limited, and may be, for example, a cylindrical shape, a rectangular parallelepiped shape, or a sheet shape formed of a film.

  The positive terminal 30 includes an external nut 36, an internal nut 32, and a bolt 34. The external nut 36 is used for connection between the positive terminal 30 and a positive wiring (not shown). The inner nut 32 is attached to the first seal member 42. A part of the inner nut 32 passes through the through hole 4b. The bolt 34 is fastened to the internal nut 32. A third seal member 40 is interposed between the bolt 34 and the case 4. The positive terminal 30 is insulated from the case 4 by the seal members 40 and 42. A first positive electrode lead 44 is fixed to the inner nut 32. The inner nut 32 and the first positive electrode lead 44 are electrically connected. The first positive electrode lead 44 is insulated from the case 4 by the first seal member 42. The positive electrode terminal 30 is electrically connected to the positive electrode of the electrode structure 2 through the first positive electrode lead 44, the current interrupt device 50, and the second positive electrode lead 45. The current interrupt device 50 will be described later.

  The negative electrode terminal 10 includes an external nut 16, an internal nut 12, and a bolt 14. The external nut 16 is used for connection between the negative electrode terminal 10 and a negative electrode wiring (not shown). The inner nut 12 is attached to the second seal member 22. A part of the inner nut 12 passes through the through hole 4c. The bolt 14 is fastened to the inner nut 12. A fourth seal member 20 is interposed between the bolt 14 and the case 4. The negative electrode terminal 10 is insulated from the case 4 by the seal members 20 and 22. A negative electrode lead 24 is fixed to the inner nut 12. The inner nut 12 and the negative electrode lead 24 are electrically connected. The negative electrode lead 24 is insulated from the case 4 by the second seal member 22. The negative electrode terminal 10 is electrically connected to the negative electrode of the electrode structure 2 through the negative electrode lead 24.

(Electrode structure)
The electrode structure 2 includes a protrusion 2 a that protrudes toward the upper surface 4 a of the case 4. The electrode structure 2 includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. Illustration of the positive electrode, the negative electrode, and the separator is omitted. The positive electrode has a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. A positive electrode current collecting tab 46 is fixed to the positive electrode. The positive electrode current collector tab 46 corresponds to a positive electrode current collector on which a positive electrode active material layer is not applied. The negative electrode has a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. A negative electrode current collecting tab 26 is fixed to the negative electrode. The negative electrode current collector tab 26 corresponds to a negative electrode current collector on which a negative electrode active material layer is not applied. Note that there are no particular limitations on materials (eg, active material, binder, and conductive additive) included in the active material layer, and materials that are used for electrodes of known power storage devices and the like can be used.

(Current interrupter)
The current interrupt device 50 is connected between the positive terminal 30 and the positive current collecting tab (positive electrode) 46. The current interrupt device 50 is disposed between the inner surface on the upper surface 4 a side of the case 4 and the convex portion 2 a of the electrode structure 2. The current interrupting device may be connected between the negative electrode and the negative terminal, or may be connected between both the positive electrode and the positive terminal and between the negative electrode and the negative terminal.

  As shown in FIG. 2, the electric current interruption apparatus 50 is provided with the metal diaphragm 56, the metal fracture | rupture board 60, and the supporting member 52 which has insulation. A support member 52 supports the diaphragm 56 and the fracture plate 60.

  A groove portion 55 is formed on the lower side of the fracture plate 60 (the side opposite to the diaphragm 56 side). The lower side of the fracture plate 60 can also be referred to as the electrode structure 2 side of the fracture plate 60. The diaphragm 56 is fixed to a connection range 60 a surrounded by the groove portion 55 of the fracture plate 60. An insulating film 54 is formed on the lower side of the fracture plate 60. The fracture plate 60 is electrically connected to the diaphragm 56. Further, the fracture plate 60 is electrically connected to the second positive electrode lead 45 (see also FIG. 1). That is, the current interrupt device 50 (diaphragm 56 and fracture plate 60) is electrically connected to the second positive electrode lead 45 that is electrically connected to the positive electrode.

  An end portion of the diaphragm 56 on the fracture plate 60 side (hereinafter referred to as the lower side of the diaphragm 56) is insulated from the fracture plate 60 by the support member 52. The diaphragm 56 includes a protrusion 56a at the center. The protruding portion 56 a is fixed to the fracture plate 60. The end of the diaphragm 56 on the upper surface 4 a side, that is, the end of the diaphragm 56 opposite to the fracture plate 60 (hereinafter referred to as the upper side of the diaphragm 56) is electrically connected to the first positive electrode lead 44. The upper side of the diaphragm 56 can also be referred to as the inner surface side of the case 4. An insulating film 58 is formed in the upper central portion of the diaphragm 56 (the portion not in contact with the first positive electrode lead 44). In the following description, the insulating film 54 is referred to as a first insulating film 54 and is referred to as an insulating film 58 and a second insulating film 58.

  The first insulating film 54 is a coating film. Specifically, the first insulating film 54 is a film coated with a curable resin. Therefore, the first insulating film 54 is formed uniformly and thinly on the lower surface of the fracture plate 60. Similarly, the second insulating film 58 is also a coating film, and is formed uniformly and thinly on the upper surface of the diaphragm 56. Examples of the material of the coating film (curable resin) include resins such as polytetrafluoroethylene (PTFE) and polyimide. The insulating films 54 and 58 may be made of a material other than a material that can be coated as long as it is an insulating material. As an example, an insulating sheet such as a PTFE sheet or a polyimide sheet can be attached to the fracture plate 60 and / or the diaphragm 56. Alternatively, an oxide film may be formed on the lower surface of the fracture plate 60 and / or the upper surface of the diaphragm 56. As an example, when the material of the fracture plate 60 and / or the diaphragm 56 is aluminum, an alumite layer can be formed by performing an oxidation treatment.

  In the state shown in FIG. 2, the positive electrode terminal 30 and the positive electrode current collector tab 46 (positive electrode) are electrically connected, and the negative electrode terminal 10 and the negative electrode current collector tab 26 (negative electrode) are electrically connected (see also FIG. 1). . For this reason, the positive electrode terminal 30 and the negative electrode terminal 10 are energized.

  When the internal pressure in the case 4 rises, the center portion of the diaphragm 56 protrudes upward as shown in FIG. The groove part 55 part of the fracture | rupture board 60 fractures | ruptures, and the connection range 60a enclosed by the groove part 55 and another range become non-conduction. As a result, the positive electrode terminal 30 and the positive electrode current collecting tab 46 become non-conductive, and the current flowing between the positive electrode terminal 30 and the negative electrode terminal 10 is interrupted. As described above, the second insulating film 58 is a coating film. Since the second insulating film 58 is a thin film, the operation of the diaphragm 56 is not disturbed.

  As described above, the current interrupt device 50 is disposed between the inner surface of the case 4 on the upper surface 4 a side and the electrode structure 2. Since the current interrupt device 50 and the electrode structure 2 are close to each other, there is a possibility that the current interrupt device 50 and the electrode structure 2 come into contact with each other during use of the power storage device 100. However, since the first insulating film 54 is formed on the lower side of the fracture plate 60, the negative electrode of the fracture plate 60 and the electrode structure 2 is short-circuited even if the current interrupt device 50 and the electrode structure 2 are in contact with each other. There is nothing.

  In the power storage device 100 described above, it is only necessary that an insulating film is formed on the current interrupt device 50, and various materials can be used for components constituting the power storage device 100. Below, the material of the components which comprise the electrode structure 2 is illustrated about the lithium ion secondary battery which is an example of the electrical storage apparatus 100. FIG.

(Positive electrode current collector)
As the positive electrode current collector, aluminum (Al), nickel (Ni), titanium (Ti), stainless steel, or a composite material thereof can be used. In particular, aluminum or a composite material containing aluminum is preferable.

(Positive electrode active material)
The positive electrode active material only needs to be a material in which lithium ions can enter and desorb, and Li ₂ MnO ₃ , Li (NiCoMn) _0.33 O ₂ , Li (NiMn) _0.5 O ₂ , LiMn ₂ O ₄ , LiMnO _2, LiNiO _2, and _{LiCoO 2, LiNi 0.8 Co 0.15 Al} 0.05 O 2, Li 2 MnO 2, LiMn 2 O 4 or the like can be used. In addition, alkali metals such as lithium and sodium, or sulfur can be used as the positive electrode active material. These may be used alone or in combination of two or more. The positive electrode active material is applied to the positive electrode current collector together with a conductive material, a binder and the like as necessary.

(Negative electrode current collector)
As the negative electrode current collector, aluminum, nickel, copper (Cu), or a composite material thereof can be used. In particular, copper or a composite material containing copper is preferable.

(Negative electrode active material)
As the negative electrode active material, a material in which lithium ions can enter and leave is used. Alkali metals such as lithium (Li) and sodium (Na), transition metal oxides containing alkali metals, natural graphite, mesocarbon microbeads, highly oriented graphite, carbon materials such as hard carbon, soft carbon, silicon alone or silicon A containing alloy or a silicon-containing oxide can be used. The negative electrode active material is particularly preferably a material that does not contain lithium (Li) in order to improve battery capacity. A negative electrode active material is apply | coated to a negative electrode collector with a electrically conductive material, a binder, etc. as needed.

(Separator)
As the separator, a porous porous material is used. As the separator, a porous film made of a polyolefin-based resin such as polyethylene (PE) or polypropylene (PP), or a woven or non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methyl cellulose or the like can be used.

(Electrolyte)
The electrolytic solution is preferably a nonaqueous electrolytic solution in which a supporting salt (electrolyte) is dissolved in a nonaqueous solvent. As a non-aqueous solvent, a solvent containing a chain ester such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl acetate, A solvent such as methyl propionate or a mixture thereof can be used. Moreover, as a supporting salt (electrolyte), for _example, can be used LiPF _6, LiBF 4, LiAsF _6, and the like.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Electrode structure 4: Case 10: Negative electrode terminal 22: Negative electrode lead 30: Positive electrode terminal 45: Positive electrode lead (second positive electrode lead)
50: Current interrupting device 54: Second insulating film (second insulating film)
55: Groove 56: Diaphragm 58: Insulating film (first insulating film)
60: Broken plate

Claims (8)

Case and
An electrode structure that is housed in the case and includes a positive electrode and a negative electrode;
A positive electrode lead electrically connected to the positive electrode;
A negative electrode lead electrically connected to the negative electrode;
A current interrupting device that is housed in the case, connected to at least one of the positive electrode lead and the negative electrode lead, and switches from a conductive state to a non-conductive state in accordance with an internal pressure in the case; ,
The current interrupting device is disposed between the electrode structure and the inner surface of the case, and has a diaphragm in which a protruding portion is formed at a central portion, and a distal end portion of the protruding portion is fixed and the distal end portion A break plate formed with a groove portion surrounding the fixed portion, and
A power storage device in which an insulating film is provided on a surface of a portion of the fracture plate that directly faces the electrode structure and faces the diaphragm . The power storage device according to claim 1, wherein among the conductive members disposed between the electrode structure and the electrode terminal, the fracture plate is disposed at a position closest to the electrode structure. A positive electrode terminal that is exposed to the outside of the case from one surface of the case, and is electrically connected to the positive electrode lead;
A negative electrode terminal exposed to the outside of the case from the one surface and electrically connected to the negative electrode lead;
The current blocking device, the power storage device according to claim 1 or 2 is arranged between the one surface of the said electrode structure case. In addition to the insulating film provided on the surface on the electrode structure side of the current interrupt device,
The power storage device according to any one of claims 1 to 3, wherein the current interrupt device further includes a second insulating film on a surface on an inner surface side of the case.   The power storage device according to claim 1, wherein the insulating film is a coating film. The electrode structure includes a convex portion protruding toward the inner surface side of the case,
The power storage device according to any one of claims 1 to 5, wherein the current interrupting device is disposed between the convex portion and an inner surface of the case.   The secondary battery which consists of a structure as described in any one of Claims 1-6.   A vehicle equipped with the power storage device according to claim 1.

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