Liquid battery

Abstract

To prevent the gas generated by the evaporation of an electrolyte from leaking out of a laminated exterior body even when the electrode body is damaged.SOLUTION: A liquid battery includes an electrode body, a laminated outer casing that encases the electrode body, a housing that covers a portion of the electrode body, is enclosed in the laminated outer casing, and is positioned between the electrode body and the laminated outer casing, and an electrolyte contained in the electrode body, and the housing contains an absorbent material that absorbs gas outside the housing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to liquid-based batteries. [Background technology]

[0002] Conventionally, liquid batteries have been used that have an electrode body, a laminated outer casing that contains the electrode body, a housing that covers part of the electrode body and is disposed between the electrode body and the laminated outer casing, and an electrolyte solution contained in the electrode body.

[0003] For example, Patent Document 1 discloses a battery pack consisting of multiple connected battery cells, in which a liquid absorbent material that absorbs electrolyte is provided for each battery cell, the liquid absorbent material being arranged near the gas seal opening of the battery cell, and the liquid absorbent material being made of a flame-retardant material.

[0004] Furthermore, Patent Document 2 discloses a lithium polymer battery that includes a positive electrode, a negative electrode, a separator, and a gel electrolyte to which a gas absorbent material is added.

[0005] Furthermore, Patent Document 3 discloses a battery that includes a casing in which a positive electrode and a negative electrode are sealed together with an electrolyte, and an explosion-proof valve for releasing high-pressure gas inside the casing when the internal pressure of the casing increases, and that further includes a gas absorber for absorbing the high-pressure gas, the gas absorber including a capsule made of a gas absorbent material and a heat-fusible material, and that is provided inside the casing, and the capsule contains the gas absorbent material inside.

[0006] Patent Document 4 also discloses a method for manufacturing a bipolar battery, which includes: a first step of preparing a battery structure having an electrode stacking portion and a primary seal portion; a second step of injecting an electrolyte solution into the battery structure through an injection hole in the primary seal portion while restraining the electrode stacking portion with a pair of restraint plates so that the distance between the pair of restraint plates sandwiching the electrode stacking portion in the stacking direction is a specified length; a third step of discharging the electrolyte solution through the injection hole by restraining the electrode stacking portion with the pair of restraint plates so that the distance between the pair of restraint plates is shorter than the specified length; and a fourth step of, after performing the third step, restraining the electrode stacking portion with the pair of restraint plates so that the distance between the pair of restraint plates is the specified length. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-103162 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-227301 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-092493 [Patent Document 4] Japanese Patent Application Publication No. 2019-091606 Summary of the Invention [Problem to be solved by the invention]

[0008] In liquid batteries, damage to the electrode body can occur. For example, in a liquid battery mounted on a vehicle, components (e.g., electrode foil) in the electrode body can be damaged by external forces such as a vehicle collision. Gas caused by volatilization of the electrolyte solution can leak from the damaged component into the space between the electrode body and the laminated outer casing. Furthermore, if the interior of the laminated outer casing is filled with gas, the pressure of the gas can cause damage to the laminated outer casing, leading to gas leakage to the outside of the laminated outer casing.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to provide a liquid battery that can prevent gas generated by volatilization of the electrolyte from leaking outside the laminated outer casing, even if the electrode body is damaged. [Means for solving the problem]

[0010] Means for solving the above problems include the following aspects. <1> An electrode body; a laminate exterior body that encloses the electrode body; a housing that covers a portion of the electrode assembly, is enclosed in the laminated exterior body, and is disposed between the electrode assembly and the laminated exterior body; an electrolyte solution contained in the electrode body, The liquid battery, wherein the housing includes an absorbent material that absorbs gas outside the housing. <2> The electrolyte contains first petroleum products, 2. The liquid battery according to claim 1, wherein the absorbent material comprises activated carbon. <3> the housing has a space therein that is in communication with the outside, The liquid battery according to claim 1 , wherein the absorbent material is disposed in the space. <4> 4. The liquid battery according to claim 3, wherein the housing has a surface with a plurality of holes communicating with the space. <5> 2. The liquid battery according to claim 1, wherein the casing containing the absorbent material is arranged to surround the electrode assembly in a direction perpendicular to the thickness direction of the electrode assembly. [Effects of the Invention]

[0011] According to the present disclosure, a liquid battery is provided that can prevent gas generated by volatilization of the electrolyte from leaking to the outside of the laminate exterior body even if the electrode body is damaged. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1(A) is a schematic top view showing a part of a liquid battery according to an embodiment of the present disclosure, and FIG. 1(B) is a schematic cross-sectional view showing a cross section in the thickness direction of an electrode assembly. [Figure 2] Figure 2(A) is a schematic perspective view showing a housing having multiple circular holes on its surface, Figure 2(B) is a schematic perspective view showing a housing having multiple elliptical holes on its surface, and Figure 2(C) is a schematic perspective view showing a housing having one elliptical hole on each side. [Figure 3] 3(A) to 3(F) are schematic top views showing the position where a housing containing an absorbent is disposed in a liquid battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Liquid battery> A liquid-based battery according to an embodiment of the present disclosure has an electrode body, a laminated outer casing that contains the electrode body, a housing that covers a portion of the electrode body, is contained in the laminated outer casing, and is positioned between the electrode body and the laminated outer casing, and an electrolyte solution contained in the electrode body. The housing includes an absorbent material that absorbs gas outside the housing.

[0014] By having the above-described configuration, the liquid battery according to the embodiment of the present disclosure can prevent gas generated by volatilization of the electrolyte from leaking outside the laminated outer casing, even if the electrode body is damaged.

[0015] In a liquid-type battery containing an electrolyte in the electrode assembly, if the electrode assembly is damaged, gas generated by the volatilization of the electrolyte may leak to the outside. For example, in a liquid-type battery mounted on a vehicle, a component (e.g., electrode foil) in the electrode assembly may be damaged by an external force such as a vehicle collision. Gas generated by the volatilization of the electrolyte may leak from the damaged component to the outside of the electrode assembly, i.e., into the inside of the laminated outer casing that houses the electrode assembly. Furthermore, if gas fills the inside of the laminated outer casing (i.e., the space between the laminated outer casing and the electrode assembly), the pressure of the gas may cause damage to the laminated outer casing, resulting in gas leakage to the outside of the laminated outer casing.

[0016] In contrast, in the liquid-phase battery according to an embodiment of the present disclosure, an absorbent material that absorbs gas outside the housing is included in a housing that covers a portion of the electrode assembly, is enclosed in a laminated outer casing, and is disposed between the electrode assembly and the laminated outer casing. Therefore, even if gas generated by volatilization of the electrolyte leaks outside the electrode assembly due to damage to the electrode assembly, the gas is absorbed by the absorbent material included in the housing. This prevents the laminated outer casing from being filled with gas, and prevents damage to the laminated outer casing due to gas pressure. As a result, gas leakage outside the laminated outer casing is suppressed.

[0017] In addition, when the electrolyte solution contains first petroleum compounds, volatilization of the electrolyte solution may generate highly flammable gas. Therefore, in the case of a liquid battery having an electrolyte solution containing first petroleum compounds, it is even more important to suppress leakage of gas to the outside of the laminated outer casing. In contrast, with the liquid battery according to the embodiment of the present disclosure, leakage of gas to the outside of the laminated outer casing is suppressed as described above.

[0018] Here, the configuration of a liquid battery according to an embodiment of the present disclosure will be described by way of an example with reference to the drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0019] Fig. 1(A) is a schematic top view showing a portion of a liquid battery, and Fig. 1(B) is a schematic cross-sectional view showing a cross section in the thickness direction of the electrode assembly. As shown in Fig. 1(B), the liquid battery 10 has a pair of first and second laminate films 6A and 6B as a laminate exterior body, but in Fig. 1(A) (schematic top view), the first laminate film 6A is omitted to clearly show the internal configuration of the liquid battery.

[0020] The liquid battery 10 includes an electrode stack 2 as an example of an electrode assembly and a resin housing 4 that covers a portion of the electrode stack 2. The housing 4 is disposed between the electrode stack 2 and a laminate exterior body that is composed of a first laminate film 6A and a second laminate film 6B. The housing 4 is enclosed within the laminate exterior body. The electrode stack 2 is composed of multiple electrodes stacked with separators interposed therebetween. These electrodes may include, for example, a stack of multiple bipolar electrodes, a negative terminal electrode, and a positive terminal electrode. The electrode stack 2 may also include a seal (e.g., a resin sealant) that seals the multiple electrodes. The seal forms an internal space between adjacent electrodes and seals the internal space. This internal space contains, for example, an electrolyte (not shown). The electrolyte is impregnated, for example, into the separators, positive electrodes, and negative electrodes that constitute the electrode stack 2.

[0021] The laminate exterior body, which is composed of laminate films 6A and 6B, encloses the electrode stack 2 and the housing 4. The edges of the laminate films 6A and 6B are welded together, sealing the interior. For example, the laminate films 6A and 6B may be films in which resin layers are formed on both sides of a metal layer.

[0022] An electrode body such as the electrode stack 2 has, for example, a substantially rectangular shape when viewed in the thickness direction of the electrode body (viewed in the direction of arrow X in FIG. 1). The rectangular electrode body can have, for example, sides with lengths of 1000 mm or more in the vertical direction and 10000 mm or more in the horizontal direction.

[0023] The housing 4 is formed into a rectangular cylindrical shape overall. The housing 4 is arranged on the side of the electrode stack 2. In other words, the housing 4 is arranged with respect to the electrode stack 2 so as to cover the entire periphery in a direction perpendicular to the thickness direction of the electrode stack 2 (the direction of arrow X in FIG. 1). The housing 4 is made up of four housing members 41, 42, 43, and 44 so as to cover the side of the rectangular electrode stack 2. The four housing members 41, 42, 43, and 44 are welded together at their respective contact portions. However, the housing members 41, 42, 43, and 44 do not have to be welded together.

[0024] 1(A) shows the housing 4 composed of four housing members 41, 42, 43, and 44, but is not limited to this. The housing 4 may be arranged so as to cover a portion of the electrode assembly. However, it is preferable that the housing 4 is arranged so as to cover both short side surfaces of the rectangular electrode stack 2 (i.e., in FIG. 1(A) , the housing 4 has housing members 42 and 43).

[0025] The housing 4 may be composed of, for example, an inner member arranged to completely cover the side surfaces of the electrode stack 2, and an outer member surrounding the inner member from the outside. In this case, the inner member and the outer member are preferably welded together at their contact points.

[0026] When the electrode stack 2 has a seal that seals the multiple electrodes, the housing 4 is provided adjacent to the outer periphery of the electrode stack 2 that has the seal. A gap may be provided between the electrode stack 2 and the housing 4.

[0027] The housing members 41, 42, 43, and 44 that make up the housing 4 are made of, for example, resin. Each of the housing members 41, 42, 43, and 44 has a space 40 inside that communicates with the outside. An absorbent material 8 that absorbs gas is disposed in the space 40. As shown in FIG. 2(A), the housing members 41, 42, 43, and 44 have a plurality of holes 402 on their surfaces that communicate with the space 40.

[0028] The housing members 41, 42, 43, and 44 constituting the housing 4 are not particularly limited in their configuration as long as they have a configuration in which the internal space 40 is connected to the outside. For example, if the housing members 41, 42, 43, and 44 have holes on their surfaces that connect to the space 40, the shape and location of the holes are not particularly limited. However, the shape and location of the holes should be such that the strength of the housing 4 is maintained. Therefore, the housing members 41, 42, 43, and 44 may have a plurality of circular holes 402 on their surfaces as shown in FIG. 2(A), a plurality of elliptical holes 404 on their surfaces as shown in FIG. 2(B), or one elongated elliptical hole 406 on each surface of the housing members 41, 42, 43, and 44 as shown in FIG. 2(C).

[0029] The absorbent material 8 is arranged so as to fill the space 40. However, the arrangement of the absorbent material 8 in the space 40 is not limited to this, and for example, a plurality of absorbent materials 8 may be arranged at intervals in the longitudinal direction of the space 40. When a plurality of absorbent materials 8 are arranged at intervals, it is preferable to arrange the absorbent materials 8 at regular intervals.

[0030] In this way, the housing 4 (specifically, housing members 41, 42, 43, 44) covering the side surface of the electrode stack 2 has a space 40 inside, has a plurality of holes 402 on the surface that communicate with the space 40, and has an absorbent material 8 disposed in the space 40. As a result, even if gas generated by volatilization of the electrolyte leaks out of the electrode stack 2 due to damage to the electrode stack 2, the gas is absorbed by the absorbent material 8 contained in the housing 4, and leakage of the gas out of the laminate exterior body formed of the laminate film 6A and the second laminate film 6B is suppressed.

[0031] The absorbent material 8 is a material that absorbs gas and is preferably a material that also has the function of absorbing liquid. By having the absorbent material 8 have the function of absorbing liquid, not only when gas leaks out of the electrode body due to volatilization of the electrolyte due to damage to the electrode body, but also when the electrolyte itself leaks out of the electrode body, the liquid can be absorbed by the absorbent material 8.

[0032] The absorbent material 8 may be, for example, a porous material having a large number of pores on its surface. Examples of porous materials include activated carbon, silica gel, zeolite, and porous polymers. Examples of porous polymers include polyurethane resin and polymethyl methacrylate resin. Activated carbon is preferred as the absorbent material 8 from the viewpoint of its gas and liquid absorption performance.

[0033] When the absorbent material 8 is a porous body, the average diameter of the pores on the surface of the porous body (the arithmetic mean value of the largest diameters of 50 pores when the surface is observed under a microscope) is preferably 0.5 Å or more and 10 Å or less, and more preferably 1 Å or more and 5 Å or less, from the viewpoint of gas absorption performance.

[0034] The electrolyte solution contained in the electrode stack 2 is not particularly limited, and a conventionally used known electrolyte solution can be used. For example, an electrolyte solution containing a first petroleum product may be used as the electrolyte solution. Although the first petroleum product generates highly flammable gases, the liquid battery according to the embodiment of the present disclosure prevents even the highly flammable gases from leaking to the outside of the laminate outer casing. An example of the first petroleum product is methyl propionate. Methyl propionate generates gases such as ethane, methane, propane, CO2, and CO.

[0035] In the liquid battery 10 shown in FIG. 1, an absorbent material 8 is disposed in the space 40 in all of the housing members 41, 42, 43, and 44 that make up the housing 4. In other words, as shown in FIG. 3(A), all four housing members are configured as absorbent housing members 4a that contain an absorbent material 8 in their spaces. However, the present invention is not limited to this configuration. For example, as shown in FIG. 3(B), the four housing members may be configured such that a pair of housing members on the short sides are absorbent housing members 4a that contain an absorbent material 8 in their spaces, and a pair of housing members on the long sides are normal housing members 4b that do not contain an absorbent material in their spaces. Furthermore, as shown in FIG. 3(C), the four housing members may be configured such that a pair of housing members on the long sides are absorbent housing members 4a that contain an absorbent material 8 in their spaces, and a pair of housing members on the short sides are normal housing members 4b that do not contain an absorbent material in their spaces. Furthermore, as shown in FIG. 3(D), the four housing members may be configured such that one housing member on the long side and one housing member on the short side are absorbent housing members 4a that contain absorbent material 8 in their spaces, and the remaining one housing member on the long side and one housing member on the short side are normal housing members 4b that do not contain absorbent material in their spaces. Furthermore, as shown in FIG. 3(E), one of the four housing members may be an absorbent housing member 4a on one of the long sides, which contains an absorbent material 8 in its space, and the remaining housing member on the long side and the two housing members on the short sides may be normal housing members 4b, which do not contain an absorbent material in their space. Furthermore, as shown in FIG. 3(F), one of the four housing members on the short side may be an absorbent housing member 4a containing an absorbent material 8 in its space, and the remaining two housing members on the long side and one housing member on the short side may be normal housing members 4b which do not contain an absorbent material in their space.

[0036] Electrode body configuration Next, an electrode assembly constituting a liquid battery according to an embodiment of the present disclosure will be described.

[0037] The electrode assembly may be, for example, an electrode stack. The electrode stack is composed of a plurality of electrodes stacked with separators interposed therebetween. The electrode may, for example, have a stack of a plurality of bipolar electrodes.

[0038] (Cathode active material layer) The electrode has a positive electrode active material layer. The positive electrode active material layer contains a positive electrode active material and may further contain, for example, a binder. An example of a positive electrode active material is lithium nickel cobalt manganese composite oxide (hereinafter, simply referred to as "LNCM"). The simplest LNCM has the following general formula: LiNi x Co yMn z It is represented by O2 (where x, y, and z satisfy 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). LNCM may contain other additive elements in addition to Li, Ni, Co, and Mn, such as transition metal elements other than Ni, Co, and Mn, and typical metal elements other than Li. LNCM has a layered crystal structure. LNCM preferably exceeds 50% by mass of the entire positive electrode active material, for example, occupies 80 - 100% by mass. The positive electrode active material may be composed of only LNCM. Also, as the positive electrode active material layer, lithium iron phosphate (LiFePO4, LFP), lithium manganese iron phosphate (LMFP), etc. may be used. Examples of other positive electrode active materials include lithium nickel composite oxides, lithium cobalt composite oxides, lithium nickel manganese composite oxides, etc.

[0039] Examples of the binder contained in the positive electrode active material layer include vinyl halide resins such as polyvinylidene fluoride (PVdF). The positive electrode active material layer may further contain other components, such as a conductive material. Examples of the conductive material include graphitizable carbon such as non-graphitizing carbon and carbon black, and graphite.

[0040] (Negative electrode active material layer) The electrode has a negative electrode active material layer. The negative electrode active material layer contains a negative electrode active material and may further contain, for example, a binder. Examples of the negative electrode active material include graphite-based carbons such as natural graphite, artificial graphite, and amorphous-coated graphite. The proportion of graphite in the graphite-based carbon is generally 50% by mass or more, preferably 80% by mass or more. Examples of the binder contained in the negative electrode active material include rubbers such as styrene-butadiene copolymers (SBR) and vinyl halide resins such as polyvinylidene fluoride (PVdF). The negative electrode active material layer may further contain other components, such as a thickener. Examples of the thickener include celluloses such as carboxymethyl cellulose (CMC).

[0041] (Current collectors: positive electrode current collector and negative electrode current collector) A liquid battery according to an embodiment of the present disclosure may include, for example, a plurality of bipolar electrodes, each having a negative electrode active material layer on one side of a current collector and a positive electrode active material layer on the other side of the current collector, stacked with a separator interposed therebetween. The current collector is preferably a conductive material made of a metal with good electrical conductivity (e.g., aluminum, stainless steel (SUS), Ni, Cr, Au, Pt, Fe, Ti, Zn, etc.).

[0042] (separator) The separator is an electrically insulating porous film. The separator electrically isolates the positive electrode and the negative electrode. The separator may have a thickness of, for example, 5 to 30 μm. The separator may be made of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, or the like. The separator may have a multilayer structure. For example, the separator may be made by laminating a porous PP film, a porous PE film, and a porous PP film in this order. The separator may have a heat-resistant layer on its surface. The heat-resistant layer contains a heat-resistant material. Examples of the heat-resistant material include metal oxide particles such as alumina, and high-melting-point resins such as polyimide.

[0043] (electrolyte) The liquid battery according to the embodiment of the present disclosure further includes an electrolyte. As the electrolyte, a non-aqueous electrolyte is particularly preferable. The non-aqueous electrolyte will be described below.

[0044] ·solvent The non-aqueous electrolytic solution contains a solvent (non-aqueous solvent) and an electrolyte. Examples of the solvent (non-aqueous solvent) include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI), and 1-ethyl-2,3-dimethylimidazolium bis(fluorosulfonyl)imide (DEMI-FSI).

[0045] ·Electrolyte The electrolyte in the electrolytic solution may be, for example, a Li salt, such as lithium bis(fluorosulfonyl)imide (LiFSI), LiPF6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF4), or Li[N(CF3SO2)2]. The amount of electrolyte may be, for example, 1.0 to 2.0 mol / L, and is preferably 1.0 to 1.5 mol / L.

[0046] In addition to the solvent and electrolyte, the electrolytic solution may contain various additives such as a thickener, a film-forming agent, a gas generating agent, etc. The electrolyte is typically a non-aqueous electrolytic solution that is liquid at room temperature (e.g., 25±10°C). The electrolytic solution typically remains liquid in the environment in which the battery is used (e.g., a temperature environment of -20 to +60°C).

[0047] (Application) Examples of applications of the liquid battery according to the embodiment of the present disclosure include power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (BEVs). [Explanation of symbols]

[0048] 2 electrode laminate, 4 housing, 41, 42, 43, 44 housing member, 6A, 6B laminate film, 8 absorbent material, 10 liquid battery, 40 space

Claims

1. An electrode body; a laminate exterior body that encloses the electrode body; a housing that covers a portion of the electrode assembly, is enclosed in the laminated exterior body, and is disposed between the electrode assembly and the laminated exterior body; an electrolyte solution contained in the electrode body, The liquid battery, wherein the housing includes an absorbent material that absorbs gas outside the housing.

2. The electrolyte contains first petroleum products, 10. The liquid battery of claim 1, wherein the absorbent material comprises activated carbon.

3. the housing has a space therein that is in communication with the outside, The liquid battery according to claim 1 , wherein the absorbent material is disposed in the space.

4. The liquid battery according to claim 3 , wherein the housing has a surface with a plurality of holes communicating with the space.

5. 2. The liquid battery according to claim 1, wherein the casing containing the absorbent material is disposed so as to surround the electrode assembly in a direction perpendicular to the thickness direction of the electrode assembly.

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