Battery

Abstract

To provide a battery with high safety and high energy density.SOLUTION: A battery comprises: one or more laminates in each of which a positive electrode provided with a positive electrode collector, an electrolyte, and a negative electrode provided with a negative electrode collector are repeatedly disposed so that at least either one of the positive electrode collector or the negative electrode collector has a plurality of collector tab groups each lead out from an end surface; an outer package which houses the laminates; a lead terminal at least partially extending to the outside of the outer package; and a plurality of overcurrent cut-off parts which are disposed inside the outer package and are electrically connected to the lead terminal. Each of the plurality of collector tab groups is electrically connected to each of the plurality of overcurrent cut-off parts.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery. [Background technology]

[0002] In recent years, the demand for high-capacity, high-output batteries has been rapidly expanding due to the widespread use of various large and small electric and electronic devices such as automobiles, personal computers, and mobile phones. Liquid battery cells that use an organic electrolyte between the positive and negative electrodes as an electrolyte are widely used for such batteries.

[0003] The above-mentioned batteries are connected to fuses to prevent damage to parts or accidents when an overcurrent flows during an abnormality. For example, secondary batteries installed to drive electric vehicles are connected to fuses that cut off the current by melting when an overcurrent occurs (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-150664 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional overcurrent interruption devices and mechanisms are designed to interrupt excessive current flowing between a battery cell and an external device. However, there is also a need to interrupt the internal short-circuit current that flows inside a battery cell due to a fault (mainly an internal short circuit) that occurs inside the battery cell. This is because the internal short-circuit current generates Joule heat, which causes the temperature of the battery cell to rise, resulting in unsafe events such as the release of toxic gases or the combustion of the battery cell.

[0006] In recent years, in addition to liquid batteries that use electrolytes as electrolytes, technologies related to solid-state batteries that use flame-retardant solid electrolytes as electrolytes have been proposed. However, even in solid-state batteries, if an internal short circuit phenomenon occurs and the temperature reaches a temperature at which a decomposition reaction occurs, a huge amount of heat is generated, which may destroy the exterior body, causing unsafe situations such as the generation of toxic gases and combustion reactions.

[0007] The present invention has been made in view of the above, and has an object to provide a battery that is highly safe and capable of reducing an internal short-circuit current and thereby reducing a temperature rise at an internal short-circuit portion. [Means for solving the problem]

[0008] (1) The present invention relates to a battery comprising: one or more laminates having a plurality of current collector tab groups each formed by repeatedly arranging a positive electrode having a positive current collector, an electrolyte, and a negative electrode having a negative current collector, the positive electrode current collector and / or the negative electrode current collector being each drawn out from an end face; an exterior housing that houses the laminate; lead terminals, at least a portion of which extends outward from the exterior housing; and a plurality of overcurrent interrupter parts disposed inside the exterior housing and electrically connected to the lead terminals, the plurality of current collector tab groups being electrically connected to the plurality of overcurrent interrupter parts, respectively.

[0009] According to the invention of (1), the internal short-circuit current can be reduced, thereby reducing the temperature rise at the internal short-circuit portion, and a highly safe battery can be provided.

[0010] (2) The battery according to (1), wherein the overcurrent interrupter is a PTC thermistor.

[0011] According to the invention of (2), the battery can be used continuously even after an overcurrent occurs without the need to replace parts.

[0012] (3) The battery according to (1) or (2), wherein the exterior body has a welded portion, and the overcurrent interrupter is disposed at the welded portion.

[0013] According to the invention of (3), even a liquid battery can be provided with an overcurrent interruption function, and the volumetric energy density of the battery can be improved.

[0014] (4) A battery component for use in the battery according to any one of (1) to (3), comprising the lead terminal and the plurality of overcurrent interrupters electrically connected to the lead terminal, which are integrated together.

[0015] According to the invention (4), the battery according to any one of (1) to (3) can be preferably constructed. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing an overview of a solid-state battery according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing an overview of a solid-state battery according to a second embodiment of the present invention. [Diagram 3] FIG. 1 is a side cross-sectional view of a solid-state battery according to one embodiment of the present invention. [Figure 4] 2 is a side cross-sectional view of an overcurrent interrupter according to an embodiment of the present invention; FIG. [Diagram 5] FIG. 2 is a perspective view showing an overcurrent interrupter according to an embodiment of the present invention. [Figure 6] 6 is a cross-sectional view taken along the line AA in FIG. 5. [Figure 7] 6 is a cross-sectional view taken along line BB in FIG. 5. [Figure 8] FIG. 2 is an exploded perspective view showing an overcurrent interrupter according to an embodiment of the present invention. [Figure 9] 1 is a graph showing the relationship between the presence or absence of an overcurrent interrupter and an initial short-circuit current. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples of the present invention, and the present invention is not limited to the following embodiments.

[0018] First Embodiment <Battery> The battery 1 according to this embodiment is a solid-state battery, and includes a laminate 100, lead terminals 200 and 210, and an exterior body 300, as shown in FIG. 1. A plurality of positive electrode collector tab groups 12A and 12B drawn out from an end face of the laminate 100 are electrically connected to a lead terminal 200 via connection plates 13a and 13b and overcurrent interrupters 400 and 401, respectively. Similarly, a plurality of negative electrode collector tab groups 22A and 22B drawn out from an end face of the laminate 100 are electrically connected to a lead terminal 210 via connection plates 13c and 13d and overcurrent interrupters 402 and 403, respectively. Hereinafter, the battery 1 will be described as a solid-state battery, but the battery 1 may be a liquid-based battery having a liquid electrolyte.

[0019] (Laminate) As shown in Fig. 3, the laminate 100 has a structure in which unit cells each including a positive electrode 10, a negative electrode 20, and a solid electrolyte 30 disposed therebetween are repeatedly stacked. The laminate 100 according to this embodiment is an example in which a stack unit of a positive electrode 10, a solid electrolyte 30, and a negative electrode 20 is repeatedly stacked a total of two times. The laminate 100 according to this embodiment is housed in a laminate cell 300 as an exterior body, but if there are a plurality of laminates 100, the laminate 100 may be a wound body housed in a cylindrical exterior body.

[0020] The positive electrode 10 has a positive electrode active material layer 11 laminated on both sides of a positive electrode current collector 12. The negative electrode 20 has a negative electrode active material layer 21 laminated on both sides of a negative electrode current collector 22. These may be separate layers, or the current collector and the active material layer may be integrated.

[0021] [Cathode active material layer] The positive electrode active material constituting the positive electrode active material layer 11 is not particularly limited, and any material known as a positive electrode active material for solid-state batteries can be used. There is also no particular limit to the composition, and the material may contain a solid electrolyte, a conductive assistant, a binder, etc. Examples of the positive electrode active material include transition metal chalcogenides such as titanium disulfide, molybdenum disulfide, and niobium selenide, and transition metal oxides such as lithium nickel oxide (LiNiO2), lithium manganate (LiMnO2, LiMn2O4), and lithium cobalt oxide (LiCoO2).

[0022] [Positive electrode current collector] The positive electrode current collector 12 is not particularly limited, and may be any known current collector that can be used for the positive electrode of a solid-state battery, such as a metal foil such as stainless steel (SUS) foil or aluminum (Al) foil.

[0023] [Negative electrode active material layer] The negative electrode active material constituting the negative electrode active material layer 21 is not particularly limited, and any material known as a negative electrode active material for solid-state batteries can be used. There is also no particular limit to the composition, and the material may contain a solid electrolyte, a conductive additive, a binder, etc. Examples of the negative electrode active material include lithium metal, lithium alloys such as Li-Al alloys and Li-In alloys, Li4Ti5O 12 and carbon materials such as carbon fiber and graphite.

[0024] [Negative electrode current collector] The negative electrode current collector 22 is not particularly limited, and any known current collector that can be used for the negative electrode of a solid-state battery can be used. For example, metal foils such as stainless steel (SUS) foil and copper (Cu) foil can be used.

[0025] [Current collector tab] The positive electrode current collector tabs 12a and 12b are drawn out substantially parallel to each other in the same direction from one end face of the laminate 100. Similarly, the positive electrode current collector tabs 12c and 12d are drawn out substantially parallel to each other in the same direction from one end face of the laminate 101. In this embodiment, the positive electrode current collector tabs are configured to extend from the respective positive electrode current collectors 12.

[0026] Similarly, the multiple negative electrode current collector tabs 22a and 22b are drawn out in a planar manner substantially parallel to each other in the same direction from the other end faces of the laminate 100 and the laminate 101. The multiple negative electrode current collector tabs may be drawn out from one end face of the laminate 100, similar to the positive electrode current collector tabs. The multiple negative electrode current collector tabs are configured to extend from the respective negative electrode current collectors 22.

[0027] In the present invention, the current collector tabs are not limited to being extended as long as they are pulled out from the respective current collectors, and may be members different from the positive current collector 12 and the negative current collector 22, for example.

[0028] The width of the current collector tab is set appropriately so that the resistance of the current collector tab portion is small depending on the purpose of use, with the width of the composite material as the maximum, but is preferably 1 mm to 1000 mm, more preferably 2 mm to 300 mm. The thickness is generally about 5 to 50 μm, and the pull-out length is generally about 5 to 50 mm.

[0029] [Current collector tab group] The positive electrode current collector tabs and the negative electrode current collector tabs are bundled into a plurality of groups to form a plurality of current collector tab groups. As shown in FIG. 1, the positive electrode current collector tab groups 12A and 12B are electrically connected to connection plates 13a and 13b, respectively. Similarly, the negative electrode current collector tab groups 22A and 22B are electrically connected to connection plates 13c and 13d, respectively. With the above configuration, the battery 1 functions as if a plurality of stacks were connected in parallel.

[0030] The joining method for joining the plurality of positive electrode collector tab groups 12A and 12B to the connection plates 13a and 13b is not particularly limited, and known methods such as welding such as resistance welding and ultrasonic welding, and welding can be used. In this embodiment, a configuration in which the plurality of positive electrode collector tab groups are electrically connected to the lead terminal 200 via the connection plates 13a and 13b and the overcurrent interrupters 400 and 401 is described, but a similar configuration can be applied to the negative electrode collector tab groups 22A and 22B. It is preferable that at least one of the plurality of positive electrode collector tab groups and the plurality of negative electrode collector tab groups is electrically connected to the lead terminals 200 and 210 via the overcurrent interrupter.

[0031] [Solid electrolyte] The solid electrolyte 30 is laminated between the positive electrode 10 and the negative electrode 20, and is formed, for example, in a layer shape. The solid electrolyte 30 is a layer containing at least a solid electrolyte material. Charge transfer can be performed between the positive electrode active material and the negative electrode active material via the solid electrolyte material.

[0032] The solid electrolyte material is not particularly limited, but examples thereof include sulfide solid electrolyte materials, oxide solid electrolyte materials, nitride solid electrolyte materials, and halide solid electrolyte materials.

[0033] (Lead terminal) 1, one end of the lead terminal 200 is electrically connected to a group of positive electrode current collector tabs by welding or the like via overcurrent interrupters 400 and 401, and the other end extends from the exterior body 300 to form an electrode part of the solid-state battery 1. Similarly, the lead terminal 210 is electrically connected to a group of negative electrode current collector tabs.

[0034] The lead terminals 200 and 210 are not particularly limited, and are preferably flexible linear plate-like members made of aluminum (Al), copper (Cu), etc. In general, the thickness of the lead terminals 200 and 210 is about 0.05 to 5 mm, which is thicker than the thickness of the current collector tab.

[0035] Lead terminal 200 is electrically connected to overcurrent interruption units 400 and 401 inside exterior body 300. That is, overcurrent interruption units 400 and 401 are disposed inside exterior body 300. Lead terminal 210 is similarly electrically connected to overcurrent interruption units 402 and 403.

[0036] (Exterior body) The exterior body 300 houses the laminates 100 and 101, the positive electrode collector tabs 12a, 12b, 12c, and 12d, and the overcurrent interrupters 400 and 401. The exterior body 300 is not particularly limited, and may be, for example, a laminate cell made of a laminate film. The laminate cell has a multilayer structure in which a heat-sealable resin layer such as polyolefin is laminated on the surface of a metal layer made of aluminum, stainless steel (SUS), or the like. The laminate cell may have, in addition to the above, a layer made of polyamide such as nylon, polyester such as polyethylene terephthalate, or an adhesive layer made of any laminate adhesive.

[0037] The laminate cell is formed by folding, for example, a rectangular laminate film so as to sandwich the laminate 100, and sealing the outside of the laminate 100 by a heat sealing method or the like, thereby housing the laminate 100 inside. The exterior body 300 is not limited to the laminate cell, and may be, for example, a metallic exterior body formed into a cylindrical shape.

[0038] [Overcurrent breaker] In this embodiment, the overcurrent interrupting units 400, 401, 402, and 403 are PTC thermistors. The resistance value of the PTC thermistor rises rapidly when the temperature exceeds a certain temperature (Curie temperature). Normally, the PTC thermistor can conduct electricity, but when an overcurrent flows through the PTC thermistor, the resistance value increases due to self-heating caused by Joule heat, and the current flowing through the PTC thermistor attenuates. This cuts off the overcurrent flowing through the PTC thermistor. By using a PTC thermistor as the overcurrent interrupting unit, the battery 1 can be continuously used without the need to replace parts even after the occurrence of an overcurrent. The PTC thermistor is not particularly limited, and for example, a semiconductor ceramic mainly composed of barium titanate can be used, and the Curie temperature can be set arbitrarily depending on the material composition. The overcurrent interrupting unit may be a fuse that melts due to an overcurrent.

[0039] 9 is a graph showing the effect of the battery having the overcurrent interrupter according to the present embodiment. The vertical axis of FIG. 9 is the initial short circuit current i 0A The initial short circuit current i OB The ratio of i OB / i 0A The horizontal axis of FIG. 9 indicates n / N, which is the ratio of the number of battery units (laminated bodies) N to the number of short-circuit units (laminated bodies) n. α is the initial short-circuit resistance R S0 R S0 / r0. The smaller the short-circuit resistance, the larger the short-circuit current, and the more likely it is that a serious unsafe event will occur. As shown in FIG. 9, it is clear that the smaller α is, the greater the short-circuit current reduction effect of the battery according to this embodiment, which indicates that the occurrence of unsafe events according to this embodiment can be suppressed. α is preferably 1 or less.

[0040] The overcurrent interrupting units 400, 401, 402, and 403 are disposed inside the exterior body 300. This eliminates the need to dispose a fuse on, for example, a bus bar outside the solid-state battery 1. This reduces the installation space of the solid-state battery 1, and as a result, improves the energy density of the solid-state battery 1. In this embodiment, the overcurrent interrupting unit is disposed at the welded portion 300a where the exterior bodies 300 are welded together. This prevents sparks from reaching the laminates 100 and 101 even when a melting-type fuse is used as the overcurrent interrupting unit and the fuse is melted. This allows the battery 1 to be configured as a liquid-based battery having a liquid electrolyte.

[0041] <Battery materials> The battery member according to the present embodiment is a member used in the battery 1, and has a structure in which a lead terminal and a plurality of overcurrent interrupting units are integrated. FIG. 4 is a diagram showing an example of the configuration of the battery member according to the present embodiment. FIG. 4 is a schematic cross-sectional view illustrating the configuration of the overcurrent interrupting units 400 and 401. As shown in FIG. 4, the overcurrent interrupting unit 400 is provided between the connection plate 13a and the lead terminal 200, and is electrically connected to each of the members. Similarly, the overcurrent interrupting unit 401 is provided between the connection plate 13b and the lead terminal 200, and is electrically connected to each of the members. The connection plate 13a is electrically connected to the plurality of positive electrode collector tab groups 12A in FIG. 1. Similarly, the connection plate 13b is electrically connected to the plurality of positive electrode collector tab groups 12B. The lead terminal 200 is electrically insulated from the connection plate 13a and the connection plate 13b by the insulating member I. The connection plate 13a and the connection plate 13b are electrically insulated from each of the members by the insulating member I.

[0042] The overcurrent interrupting units 400 and 401 are provided for each of the multiple positive electrode collector tab groups, and are electrically connected to the respective positive electrode collector tab groups via the connection plate 13a and the connection plate 13b. The overcurrent interrupting units 400 and 401 are electrically connected to the single lead terminal 200. This makes it possible to suppress the internal short circuit current flowing from the location where the internal short circuit occurred to the stack connected to the other positive electrode collector tab group when an internal short circuit current occurs in any of the stacks connected to the positive electrode collector tab group. This makes it possible to suppress the temperature rise of the battery 1 and to suppress unsafe events. In addition to the above, the overcurrent flowing from the connection plate connected to the stack where the internal short circuit occurred to the lead terminal 200 side is interrupted, but the current flowing from the connection plate connected to the stack where the internal short circuit does not occur to the lead terminal 200 side is maintained. This makes it possible to prevent the overcurrent from flowing to the outside through the lead terminal 200 when an internal short circuit occurs without stopping the device to which the battery 1 is connected. At the same time, an overcurrent flowing from the outside into the laminate 100 is cut off by the overcurrent cut-off units 400 and 401 .

[0043] Hereinafter, other embodiments of the present invention will be described. Descriptions of configurations similar to those of the first embodiment will be omitted in some cases.

[0044] Second Embodiment <Battery> 2, the battery 1a according to this embodiment has a plurality of laminates 100 and 101, a lead terminal 200, and an exterior body 300. The plurality of laminates 100 and 101 are electrically independent inside the battery 1a. A plurality of positive electrode current collector tabs 12a and 12b drawn out from an end face of the laminate 100, and a plurality of positive electrode current collector tabs 12c and 12d drawn out from an end face of the laminate 101 are electrically connected to the lead terminal 200 via connection plates 13a and 13b and overcurrent interrupters 400 and 401, respectively.

[0045] The laminate 101 has a similar configuration to the laminate 100. The laminate 100 and the laminate 101 are electrically independent, and an insulator such as an insulating sheet is disposed between the laminates (not shown). The overcurrent interrupting units 400 and 401 are each electrically connected to a single lead terminal 200. This makes it possible to more reliably suppress the internal short-circuit current flowing from the laminate where the internal short circuit has occurred to the other laminate when an overcurrent occurs due to an internal short circuit in either of the laminates 100 and 101 constituting the battery 1a. In addition, the overcurrent flowing from the connection plate connected to the laminate where the internal short circuit has occurred to the lead terminal 200 side is interrupted, but the current flowing from the connection plate connected to the laminate where the internal short circuit has not occurred to the lead terminal 200 side is maintained.

[0046] Third Embodiment <Battery materials> FIG. 5 is a diagram showing the configuration of a battery member including an overcurrent interrupting unit 400 according to this embodiment. As shown in FIG. 5, FIG. 6, FIG. 7, and FIG. 8, as in the first embodiment, two overcurrent interrupting units, 400 and 401, are provided. The overcurrent interrupting units 400 and 401 are PTC thermistors, and the periphery in the thickness direction is covered with an insulator I. The insulator I is a plate-like member provided for each of the overcurrent interrupting units 400 and 401, and has a gap capable of accommodating the overcurrent interrupting unit. The upper surface of the overcurrent interrupting unit 400 is disposed so as to abut against the connection plate 13a, and the lower surface is disposed so as to abut against the lead terminal 200. Similarly, the upper surface of the overcurrent interrupting unit 401 is disposed so as to abut against the lead terminal 200, and the lower surface is disposed so as to abut against the connection plate 13b. Each member thus configured is sandwiched and fixed from above and below by gaskets Ga and Gb. As a result, each member is electrically connected at the abutting point. Furthermore, the connection plates 13 a and 13 b do not come into direct contact with the lead terminal 200 , but are electrically connected to the lead terminal 200 via the overcurrent interrupters 400 and 401 .

[0047] The connecting plates 13a and 13b have an area larger than the total area of ​​the overcurrent interrupting parts 400 and 401 and the insulator I in a plan view, and are arranged so as to completely cover the overcurrent interrupting parts 400 and 401 and the insulator I. In Fig. 6 and Fig. 7, the ends C1, C2, and C3 of the connecting plates 13a and 13b are preferably crimped to reduce the contact resistance between the overcurrent interrupting parts 400 and 401 and the connecting plates 13a and 13b. It is preferable that the connecting plate 13a is crimped in a state where it is electrically connected only to the overcurrent interrupting part 400, and the connecting plate 13b is crimped in a state where it is electrically connected only to the overcurrent interrupting part 401.

[0048] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and appropriate modifications that do not impair the effects of the present invention are also included in the scope of the present invention. [Explanation of symbols]

[0049] 1, 1a battery 10 positive electrode 12 Positive electrode current collector 12A, 12B Positive electrode collector tab group (collector tab group) 12a, 12b, 12c, 12d Positive electrode current collector tabs 20 negative electrode 22 Negative electrode current collector 22A, 22B Negative electrode current collector tab group (current collector tab group) 30 Solid electrolyte 100, 101 Laminate 200, 210 Lead terminal 300 Exterior 300a welded part 400, 401, 402, 403 Overcurrent breaker

Claims

1. one or more laminates each including a positive electrode having a positive electrode current collector, an electrolyte, and a negative electrode having a negative electrode current collector, the positive electrode current collector and / or the negative electrode current collector being repeatedly arranged, the laminate having a plurality of current collector tab groups each formed by drawing out the end faces of the positive electrode current collector and / or the negative electrode current collector; An exterior body that houses the laminate; a lead terminal at least a portion of which extends outward from the exterior body; a plurality of overcurrent interruption units disposed inside the exterior body and electrically connected to the lead terminals; the plurality of collector tab groups are electrically connected to the plurality of overcurrent interruption units, respectively; A battery, wherein the exterior body has a welded portion, and the overcurrent interrupter is disposed at the welded portion.

2. The battery according to claim 1 , wherein the overcurrent interrupter is a PTC thermistor.

3. A battery member for use in the battery according to claim 1 or 2, The lead terminal and the plurality of overcurrent interrupting parts electrically connected to the lead terminal are integrated into a battery member.

Images