Electrode for solid-state battery

Abstract

Electrode for a solid-state battery, the electrode comprising: a current collector, which is a porous metal body; and an electrode material mixture with which the current collector is filled, wherein the current collector has an end portion which has a region not filled with the material mixture, which is not filled with the electrode material mixture, wherein the region not filled with material mixture has a part which is a fuse function section, the fuse function section having a smaller total cross-sectional area of metal in a cross section perpendicular to a direction of the end section than the rest of the region not filled with material mixture, wherein at least a part of the fuse function portion is filled with at least one of an insulating material, a reinforcing material and a heat-insulating material.

Description

[0001] This application is based on and claims priority from Japanese Patent Application No. 2020-188540, filed on November 12, 2020, the contents of which are incorporated herein by reference. Background of the inventionField of the invention

[0002] The present invention relates to an electrode for a solid-state battery. Technical background

[0003] Recently, the demand for high-capacity, high-output batteries has grown rapidly due to the proliferation of various electrical and electronic devices of various sizes, such as automobiles, personal computers, and mobile phones. As such a battery, a liquid battery cell, in which an organic electrolyte solution is used as an electrolyte between a positive and negative electrode, is widely used.

[0004] The battery is used in conjunction with a fuse to prevent component damage or accidents when an overcurrent flows during abnormal conditions. For example, a secondary battery installed for driving an electric vehicle is used in conjunction with a fuse that interrupts current by blowing due to an overcurrent (see, for example, Patent Document 1).

[0005] Patent Document 1: Japanese Unexamined Patent Application, Publication JP 2014 - 150 664 A

[0006] Furthermore, reference should be made to the publication US 2006 / 0 046 157 A1, which teaches an electrode with a current collector, which is a porous metal body, and an electrode material mixture in the current collector, wherein the current collector further has an end section free of the material mixture. Reference should also be made to DE 692 18 587 T2 and JP 2004-311 073 A, which each disclose current collectors with fuses. For the sake of completeness, reference should also be made to US 2012 / 0 263 993 A1, which also teaches an electrode with a current collector filled with an electrode material mixture. Summary of the invention

[0007] A flammable electrolyte solution is widely used as the electrolyte of the liquid battery cell. If a fuse is installed inside the battery, a spark generated when the fuse blows may cause the electrolyte solution to ignite and burn. Accordingly, as disclosed in Patent Document 1, a battery containing a flammable electrolyte solution is used by connecting it to a fuse external to the battery. However, it is preferable that the fuse be located near a location where a chemical reaction occurs, in view of faster detection of abnormalities and reducing accident risks.

[0008] At the same time, in recent years, techniques related to a solid-state battery have been proposed that use a flame-retardant solid electrolyte as an electrolyte. Among them, it has been proposed to use a porous metal as a current collector constituting a positive electrode layer and a negative electrode layer as a method for increasing the filling density of an electrode active material. In a solid-state battery, even if a fuse is provided in the battery cell, there is no risk of ignition accidents, unlike a liquid battery cell. However, a preferred fuse structure for solid-state batteries has not yet been investigated.

[0009] In response to the above problem, an object of the present invention is to provide a solid-state battery having higher safety and higher energy density.

[0010] (1) A first aspect of the present invention relates to an electrode for a solid-state battery. The electrode comprises a current collector, which is a porous metal body, and an electrode mixture material with which the current collector is filled. The current collector has an end portion having a mixture-unfilled region that is not filled with the electrode mixture material. The mixture-unfilled region has a part that is a fuse function portion. The fuse function portion has a smaller total cross-sectional area of metal in a cross section perpendicular to a direction of the end portion than the rest of the mixture-unfilled region.

[0011] According to the invention of the first aspect, it is possible to provide a solid-state battery with higher safety and higher energy density.

[0012] (2) In a second aspect of the present invention according to the first aspect, the fuse function portion has a higher porosity and / or a smaller metal wire diameter than the rest of the region not filled with the material mixture.

[0013] According to the invention of the second aspect, it is possible to form a fuse function portion having a fuse function by adjusting the porosity in a region not precipitated with material mixture.

[0014] In any case, according to the invention, at least a part of the fuse function section is filled with at least one of an insulating material, a reinforcing material and a heat-insulating material.

[0015] Accordingly, according to the invention, it is possible to improve the strength of a fuse function portion and to provide a solid-state battery with higher safety. Brief description of the drawings Fig. 1 is a diagram showing a solid-state battery according to an embodiment of the present invention. Fig. 2 is a side cross-sectional view showing an electrode for the solid-state battery according to the embodiment of the present invention; Fig. 3 is a top cross-sectional view showing the electrode for the solid-state battery according to the embodiment of the present invention; Fig. 4 is a plan view showing an electrode for a solid-state battery according to another embodiment of the present invention; and Fig. 5 is a cross-sectional view taken along the line AA in Fig. 4. Detailed description of the invention

[0016] Embodiments of the present invention will now be described with reference to the drawings. However, the following embodiments illustrate the present invention by way of example, and the present invention is not limited to the following embodiments. <<Erste Ausführungsform> > <feststoffbatterie>

[0017] As in Fig. As shown in FIG. 1, a solid-state battery 1 according to the present embodiment includes a laminate of a positive electrode 10, a negative electrode 30, and a solid electrolyte 20 disposed between the positive electrode 10 and the negative electrode 30. The solid-state battery 1 is obtained by sandwiching and pressing the laminate from the outside of the positive electrode 10 and the negative electrode 30. (Positive electrode and negative electrode)

[0018] The positive electrode 10 and the negative electrode 30, which are electrodes for the all-solid-state battery according to the present embodiment, each include a current collector, which is a porous metal body, and an electrode material mixture with which the current collector is filled. In the following description, the positive electrode 10 will be described as an example, and the same structure can be applied to the negative electrode 30. [Current collector]

[0019] The current collectors constituting the positive electrode 10 and the negative electrode 30 are each made of a porous metal body. The porous metal body has pores that are continuous with each other, and the pores may be filled with an electrode material mixture containing an electrode active material. The shape of the porous metal body is not limited as long as it has pores that are continuous with each other. Examples of the shape of the porous metal body include a foamed metal having pores formed by foaming, a metal mesh, an expanded metal, a stamped metal, and a nonwoven metal structure. The metal used in the porous metal body is not limited as long as it has electrical conductivity. Examples include nickel, aluminum, stainless steel, titanium, copper, and silver.Of these, foamed aluminum, foamed nickel, and foamed stainless steel are preferred as the current collector forming the positive electrode. Foamed copper and foamed stainless steel are preferred as the current collector forming the negative electrode.

[0020] The current collector, which is a porous metal body, has pores that are internally continuous with each other and has a surface area larger than that of a conventional current collector, which is a metal foil. By using the above-described porous metal body as a current collector, the pore can be filled with an electrode mixture material including an electrode active material. This allows the amount of active material per unit area of the electrode layer to be increased, and thus the volumetric energy density of the all-solid-state battery can be improved. In addition, since the electrode mixture material is easily adhered, it is not necessary to thicken a coating composition for forming the electrode mixture material layer when a film of the electrode mixture material layer is thickened, unlike a conventional electrode that uses a metal foil as a current collector.Therefore, it is possible to reduce the amount of a binder, such as an organic polymer compound, which was necessary for thickening. Accordingly, the capacity per unit area of the electrode can be increased, and a higher capacity of the all-solid-state battery can be achieved.

[0021] The structure of the current collector will be described with reference to the positive electrode 10 as an example, and the same structure can be applied to the negative electrode 30. Fig. 2 is a side cross-sectional view showing an aspect of the positive electrode 10 according to the present embodiment. As shown in Fig. As shown in Figure 2, the positive electrode 10 includes a mixture-filled region 11 filled with the positive electrode mixture, a mixture-unfilled region 12, and a current-collecting strip-forming portion 13. The mixture-unfilled region 12 and the current-collecting strip-forming portion 13 are not filled with the positive electrode mixture. The density of the current-collecting strip-forming portion 13 is higher than the density of the mixture-unfilled region 12.The above-described structure is manufactured because, after the mixture-filled region 11 is filled with the positive electrode mixture material, the current-collecting strip forming portion 13, which is farther from the mixture-filled region 11 than the non-mixture-filled region 12, can be easily expanded during rolling for the purpose of improving the filling density of the positive electrode active material 10 and thinning the layer. The current-collecting strip forming portion 13 is connected to a conductor strip (not shown) by welding or the like. [Electrode material mixture]

[0022] The electrode material mixture with which the mixture-filled region 11 of the current collector is filled includes at least one electrode active material. The electrode material mixture applicable to this embodiment may optionally include other components as long as it includes an electrode active material as an essential component. The other components are not limited and may be any components that can be used in manufacturing a solid-state battery. Examples include a solid electrolyte, a conductivity aid, and a binder.

[0023] The positive electrode material mixture forming the positive electrode 10 contains at least one positive electrode active material and may include other components such as a solid electrolyte, a conductivity aid, and a binder. The positive electrode active material is not limited as long as it can occlude and release lithium ions. Examples include LiCoO2, Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O2, Li(Ni 6 / 10 Co 2 / 10 Mn 2 / 10 )O2. Li(Ni 8 / 10 Co 1 / 10 Mn 1 / 10 )O2, Li(Ni 0,8 Co 0,15 Al 0,05 )O2, Li(Ni 1 / 6 Co 4 / 6 Mn 1 / 6 )O2, Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O2, Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O2, LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide and sulfur.

[0024] The negative electrode material mixture constituting the negative electrode 30 contains at least one negative electrode active material and may include other components, such as a solid electrolyte, a conductivity aid, and a binder. The negative electrode active material is not limited as long as it can occlude and release lithium ions. Examples include metallic lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, Si, SiO, and carbon materials such as artificial graphite, natural graphite, hard carbon, and soft carbon. [Solid electrolyte]

[0025] The solid electrolyte 20 is laminated between the positive electrode 10 and the negative electrode 30 and is formed, for example, in the form of a layer. The solid electrolyte 20 is a layer containing at least one solid electrolyte material. Charge transfer between the positive electrode active material and the negative electrode active material can be performed using the solid electrolyte material.

[0026] The solid electrolyte material is not limited, and examples thereof may include a sulfide solid electrolyte material, an oxide solid electrolyte material, a nitride solid electrolyte material, and a halide solid electrolyte material.

[0027] In addition to the above, the all-solid-state battery 1 includes a lead terminal and an outer packaging body. First ends of the lead terminals are electrically connected by welding or the like to current collecting strip forming portions of the positive electrode 10 and the negative electrode 30, respectively, and other ends thereof extend from the outer packaging body to respectively form electrode portions of the all-solid-state battery. The lead terminal is not limited, and for example, a flexible linear plate-like member such as aluminum or copper is used. The outer packaging body accommodates the laminate comprising the positive electrode 10, the solid electrolyte 20, and the negative electrode 30, as well as part of the lead terminals. The outer packaging body is not limited, and for example, a laminate cell made of a laminate film is used. [Area not filled with material mixture]

[0028] The non-mixed material region 12 is formed by leaving a portion of the current collector unfilled with the electrode material mixture. The non-mixed material region 12 includes a fuse function section that has a fuse function. (Security function section)

[0029] The fuse function portion is formed in a part of the mixture-unfilled region 12 as a portion in which the total cross-sectional area of a metal portion constituting the porous metal body is smaller than that of the rest of the mixture-unfilled region 12. The cross section is perpendicular to the direction of an end portion. The direction of the end portion is the extension direction of the current-collecting strip-forming portion 13, which is the direction in which electrons flow. In the present embodiment, the mixture-unfilled region 12 includes a fuse function portion 121. Fig. 3 is a top cross-sectional view showing one aspect of the positive electrode 10 according to the present embodiment. As shown in Fig. 2 and Fig. 3, the fuse function portion 121 is formed, for example, in the form of a layer perpendicular to the extending direction of the current collecting strip forming portion 13, which is the direction in which electrons flow.

[0030] A rated current is set in the fuse function section 121. When an overcurrent (fuse current) exceeding the rated current flows through the fuse function section 121, the fuse function section 121 burns out due to heat. Therefore, an abnormality occurs. When an overcurrent flows to the fuse function section 121, the fuse function section 121 burns out, and the solid-state battery 1 and an external device are protected. The overcurrent can be any of an external short-circuit current flowing from the outside of the solid-state battery 1 to the solid-state battery 1 or an internal short-circuit current flowing from the inside of the solid-state battery 1 to the outside.

[0031] In the present embodiment, the fuse function portion 121 has a higher porosity and / or a smaller metal wire diameter than the rest of the mixture-unfilled region 12. At the same time, the metal wire diameter refers to the diameter of the linear metal portion constituting the porous metal body. Therefore, the fuse function portion 121 preferably burns out when an overcurrent occurs. Accordingly, it is possible to set the rated current at which the fuse function portion 121 burns out in the fuse function portion 121 by adjusting the porosity and / or the metal wire diameter.

[0032] The fuse function portion 121 is formed, for example, in the following manner: The mixture-filled region 11 of the current collector is filled with the positive electrode mixture material, and then the positive electrode 10 is rolled, and the mixture-unfilled region 12 and the current collecting strip forming portion 13 are formed. Subsequently, a portion of the mixture-unfilled region 12 is corroded with a chemical substance such as an acid or a halide, or subjected to laser treatment, thus forming the fuse function portion 121. Alternatively, when manufacturing a porous metal body used as a current collector, a portion with a higher porosity and / or a smaller metal wire diameter is provided in a part of the porous metal body, and this portion can be used as the fuse function portion 121.

[0033] According to the present invention, at least a portion of the pores of the fuse functional portion 121 is filled with at least one of an insulating material, a reinforcing material, and a heat-insulating material. This can improve the strength of the fuse functional portion 121, which has high porosity and low physical strength. This can prevent breakage of the fuse functional portion 121 due to physical stress and a short circuit caused by the breakage. Furthermore, this can prevent the positive electrode 10 from slipping into the cell when the fuse functional portion 121 melts, thereby suppressing a short circuit caused by the slippage.

[0034] The insulating material is not limited as long as it has electrically insulating properties and can be fixed in a state of filling a gap of the fuse function portion 121. The reinforcing material is not limited as long as it meets the conditions for the insulating material and has a predetermined thickness. The heat-insulating material is not limited as long as it meets the conditions for the insulating material and has a thermal conductivity of a certain value or less. Examples of the insulating material, the reinforcing material, and the heat-insulating material include metal oxides such as alumina, synthetic resins, and mixtures thereof.

[0035] The synthetic resin is not limited, and examples thereof include heat-setting resins such as a polyimide resin, an epoxy resin, a silicon resin, and a polyurethane resin; thermoplastic resins such as a polyolefin resin, a polystyrene resin, a fluororesin, a polyvinyl chloride resin, a polymethacrylic acid resin, and a polyurethane resin; and photocurable resins such as a silicon resin, a polymethacrylic acid resin, and a polyester resin.

[0036] The fuse functional portion 121 is formed by using a portion of the region 12 not filled with the material mixture. This allows the fuse functional portion 121 to be disposed near the laminate where an electrochemical reaction occurs, thereby shortening the time until the current is cut off in the event of an abnormality and reducing the risk of an accident. In addition to the above, by disposing the fuse functional portion 121 inside the all-solid-state battery 1, it becomes unnecessary to dispose a fuse outside the all-solid-state battery 1, for example, on a bus bar. Accordingly, the installation space of the all-solid-state battery 1 can be reduced, and therefore the volumetric energy density of the all-solid-state battery 1 can be improved.

[0037] In the present embodiment, a structure has been described in which the fuse function portion 121 is provided in the positive electrode 10. It is preferable that a fuse function portion having the same structure is also provided in the negative electrode 30. Further, in the all-solid-state battery 1 in which a plurality of positive electrodes 10 and negative electrodes 30 are laminated, it is preferable that the plurality of positive electrodes 10 and negative electrodes 30 are each provided with a fuse function portion.

[0038] Another embodiment of the present invention will be described below. A description of the same structure as that of the first embodiment will be omitted. <<Zweite Ausführungsform> >

[0039] Fig. 4 is a plan view showing a positive electrode 10a according to a second embodiment. In the present embodiment, a mixture-material-unfilled region 12 includes a fuse function portion 122.

[0040] The fuse function section 122 is formed, for example, to have a region n having a smaller cross-sectional area of a porous metal body than the rest of the mixture-unfilled region 12 in a cross section perpendicular to the extension direction of a current collecting strip forming section 13, which is the direction in which electrons flow. Fig. 5 is a cross-sectional view taken along the line AA in Fig. 4. As in Fig. 5, the region n of the fuse functional section 122 has a smaller cross-sectional area of the porous metal body than the rest of the region 12 not filled with material mixture.

[0041] With the above structure of the fuse functional portion 122, the fuse functional portion 122 preferentially blows when an overcurrent occurs, similar to the fuse functional portion 121. Accordingly, it is possible to set a rated current at which the fuse functional portion 122 blows in the fuse functional portion 122 by adjusting the above cross-sectional area of the fuse functional portion 122.

[0042] According to the invention, at least a portion of pores of the region n is filled with at least one of an insulating material, a reinforcing material, and a heat-insulating material. It is also preferable that at least one of an insulating material, a reinforcing material, and a heat-insulating material be similarly disposed in a region 123 around the region n. This can improve the strength of the fuse function portion 122, which includes the region n with a smaller cross-sectional area of the porous metal body than the rest of the mixture-material-unfilled region 12. Regarding the insulating material, the reinforcing material, and the heat-insulating material mentioned above, the same structure as in the first embodiment can be adopted.

[0043] The fuse function portion 122 is formed, for example, in the following manner: the mixture-filled region 11 of the current collector is filled with the positive electrode mixture, and then the positive electrode 10a is rolled, and the mixture-unfilled region 12 and the current collecting strip forming portion 13 are formed. Subsequently, a part of the mixture-unfilled region 12 is removed, thus forming the fuse function portion 122. Alternatively, when manufacturing a porous metal body used as a current collector, a portion with a smaller cross-sectional area is provided in a part of the porous metal body, and this portion can be used as the fuse function portion 122.

[0044] Preferred embodiments of the present invention have been described above. The present invention is not limited to the above embodiments and can be modified as appropriate. Explanation of reference symbols 1 solid-state battery 10, 10a Positive electrode (electrode for solid-state battery) 12 area not filled with material mixture 121, 122 Fuse functional section

[0045] To provide a solid-state battery with high safety and high energy density, an electrode for a solid-state battery comprises a current collector, which is a porous metal body, and an electrode material mixture with which the current collector is filled. The current collector has an end portion with a material mixture-unfilled region that is not filled with the electrode material mixture. The material mixture-unfilled region has a part that is a fuse function portion. The fuse function portion has a smaller total cross-sectional area of metal in the cross section perpendicular to a direction of the end portion than the rest of the material mixture-unfilled region. Fig. 2)< / feststoffbatterie>

Claims

[1] An electrode for a solid-state battery, the electrode comprising: a current collector, which is a porous metal body; and an electrode material mixture with which the current collector is filled, wherein the current collector has an end portion which has a region not filled with the material mixture, which is not filled with the electrode material mixture, wherein the region not filled with material mixture has a part which is a fuse function section, the fuse function section having a smaller total cross-sectional area of metal in a cross section perpendicular to a direction of the end section than the rest of the region not filled with material mixture, wherein at least a part of the fuse function portion is filled with at least one of an insulating material, a reinforcing material and a heat-insulating material. [2] The electrode for a solid-state battery according to claim 1, wherein the fuse function portion has a higher porosity and / or a smaller metal wire diameter than the rest of the region not filled with the material mixture.

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