Electrode for lithium ion secondary battery and method for producing the same

Abstract

The problem to be solved by the present invention is to provide an electrode for a lithium ion secondary battery and a method for manufacturing the same that can suppress the generation of short circuits or contamination. In order to solve the above problems, the present invention provides an electrode for a lithium ion secondary battery, which is used in a lithium ion secondary battery, and the electrode includes a current collector composed of a metal porous body, and the current collector includes: a composite material layer, which is impregnated with an electrode composite material containing an electrode active material; and a composite material non-impregnated portion, which is not impregnated with the electrode composite material and is composed of a pole ear portion and a pole ear narrowing portion; and the surface roughness Ra of the composite material non-impregnated portion is less than the surface roughness Ra of the composite material layer.

Description

Technical Field

[0001] The invention relates to an electrode for a lithium ion secondary battery and a method for manufacturing the same. Background Art

[0002] In the past, lithium-ion secondary batteries have been widely used as secondary batteries with high energy density. Lithium-ion secondary batteries have the following structure: for example, a separator is present between a positive electrode and a negative electrode, and a liquid electrolyte is filled. In recent years, a technology has also been proposed, which is related to lithium-ion secondary batteries using solid electrolytes as electrolytes.

[0003] On the other hand, a technology has been proposed that uses a metal porous body as a current collector constituting a positive electrode and a negative electrode. By using a metal porous body as a current collector, an electrode composite material containing an electrode active material can be impregnated inside the porous body, thereby further improving the energy density of the battery.

[0004] When a metal porous body is used as a current collector, a composite material non-impregnated portion that is not impregnated with an electrode composite material is provided on the metal porous body, and is electrically connected to a lead tab or the like. The composite material non-impregnated portion includes a pore portion and a metal portion, and is formed with concave-convex portions on the surface. Therefore, for example, when laminating electrodes when manufacturing a lithium-ion secondary battery, if a portion of the composite material non-impregnated portion contacts other electrodes, a short circuit may occur, or stress is concentrated on a convex portion on the surface, and as a result, pollution may occur due to the wire of the metal porous body being cut off.

[0005] [Prior Technical Literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-035818 Summary of the invention

[0008] [Problems to be solved by the invention]

[0009] Patent Document 1 states that by defining the surface roughness Rmax of the solid electrolyte layer side of the electrode composite material layer, the active material particles penetrate between the positive and negative electrodes to reliably prevent short circuits. However, no research has been conducted on technologies that can prevent short circuits or contamination caused by the non-impregnated portion of the composite material.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrode for a lithium ion secondary battery and a method for producing the same which can suppress the occurrence of a short circuit or contamination.

[0011] [Technical means to solve the problem]

[0012] (1) The present invention relates to an electrode for a lithium ion secondary battery, which is used in a lithium ion secondary battery, the electrode comprising a current collector composed of a metal porous body, the current collector comprising: a composite material layer, which is impregnated with an electrode composite material containing an electrode active material; and a composite material non-impregnated portion, which is not impregnated with the electrode composite material; and the surface roughness Ra of the composite material non-impregnated portion is less than the surface roughness Ra of the composite material layer.

[0013] According to the invention of (1), it is possible to provide an electrode for a lithium ion secondary battery which can suppress short circuits and contamination in the composite material non-impregnated portion, where it is important to suppress short circuits and the like without transferring lithium ions.

[0014] (2) An electrode for a lithium-ion secondary battery according to (1), wherein the portion not impregnated with the composite material comprises: a pole ear portion having a metal density higher than that of the composite material layer; and a pole ear narrowing portion formed between the composite material layer and the pole ear portion; and the surface roughness Ra of the pole ear narrowing portion is less than 1 / 10 of the thickness of the composite material layer.

[0015] According to the invention of (2), it is possible to provide an electrode for a lithium ion secondary battery which can suppress the occurrence of a short circuit or contamination due to contact between the tab narrowing portion and other electrodes.

[0016] (3) An electrode for a lithium-ion secondary battery according to (1) or (2), wherein the portion not impregnated with the composite material comprises: a pole ear portion having a metal density higher than that of the composite material layer; and a pole ear narrowing portion formed between the composite material layer and the pole ear portion; and the surface roughness Ra of the pole ear narrowing portion is less than the average wire diameter of the metal porous body.

[0017] According to the invention of (3), it is possible to provide an electrode for a lithium ion secondary battery which can better suppress the occurrence of a short circuit or contamination due to the contact between the narrowed portion of the tab and other electrodes.

[0018] (4) An electrode for a lithium-ion secondary battery according to any one of (1) to (3), wherein the portion not impregnated with the composite material includes: a pole ear portion having a metal density higher than that of the composite material layer; and a pole ear narrowing portion formed between the composite material layer and the pole ear portion; and the surface roughness Ra of the pole ear portion is less than 1 / 10 of the thickness of the composite material layer.

[0019] According to the invention of (4), it is possible to provide an electrode for a lithium ion secondary battery which can suppress the occurrence of a short circuit or contamination due to contact between the tab portion and other electrodes, and welding defects when welding the tab portion.

[0020] (5) An electrode for a lithium-ion secondary battery according to any one of (1) to (4), wherein the portion not impregnated with the composite material includes: a pole ear portion having a metal density higher than that of the composite material layer; and a pole ear narrowing portion formed between the composite material layer and the pole ear portion; and the surface roughness Ra of the pole ear portion is less than the average wire diameter of the metal porous body.

[0021] According to the invention of (5), it is possible to provide an electrode for a lithium ion secondary battery which can better suppress the occurrence of a short circuit or contamination due to contact between the tab portion and other electrodes, and welding defects when welding the tab portion.

[0022] (6) The electrode for a lithium ion secondary battery according to any one of (1) to (5), wherein at least a surface of the portion not impregnated with the composite material is filled with a filler.

[0023] According to the invention of (6), the surface roughness Ra of the portion not impregnated with the composite material can be easily adjusted.

[0024] (7) The lithium ion secondary battery electrode according to (6), wherein the filler is at least one of an insulator and a thermal conductor.

[0025] According to the invention of (7), it is possible to suppress the occurrence of short circuit or contamination caused by the contact between the non-impregnated portion of the composite material and other electrodes, and to obtain a good heat dissipation effect.

[0026] (8) In addition, the present invention relates to a method for manufacturing an electrode for a lithium-ion secondary battery, which comprises: an electrode composite material impregnation step, in which the electrode composite material is impregnated into a part of a current collector composed of a metal porous body; and a pressing step, in which the current collector is pressed so that the surface roughness Ra of the composite material-unimpregnated part of the current collector that is not impregnated with the electrode composite material is less than 1 / 10 of the thickness of the composite material layer.

[0027] According to the invention of (8), it is possible to produce an electrode for a lithium ion secondary battery which can suppress the occurrence of a short circuit or contamination due to contact between a portion not impregnated with a composite material and other electrodes.

[0028] (9) In addition, the present invention relates to a method for manufacturing an electrode for a lithium-ion secondary battery, which comprises: an electrode composite material impregnation step, in which the electrode composite material is impregnated into a part of a current collector composed of a metal porous body; and a pressing step, in which the aforementioned current collector is pressed so that the surface roughness Ra of the composite material-unimpregnated part of the aforementioned current collector that is not impregnated with the aforementioned electrode composite material is less than the average wire diameter of the aforementioned metal porous body.

[0029] According to the invention of (9), it is possible to produce an electrode for a lithium ion secondary battery which can better suppress the occurrence of short circuits or contamination caused by contact between a portion not impregnated with a composite material and other electrodes.

[0030] (10) The method for producing an electrode for a lithium ion secondary battery according to (8) or (9), further comprising, before the pressing step, a filler filling step of filling the filler into at least the surface of the composite material non-impregnated portion.

[0031] According to the invention of (10), when producing an electrode for a lithium ion secondary battery, the surface roughness Ra of the portion not impregnated with the composite material can be easily adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a side view showing a lithium ion battery according to one embodiment of the present invention.

[0033] Figure 2 This is a side cross-sectional view showing an electrode for a lithium ion secondary battery according to one embodiment of the present invention. DETAILED DESCRIPTION

[0034] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are for illustrative purposes only and the present invention is not limited to the following embodiments.

[0035] <Electrodes for lithium-ion secondary batteries>

[0036] The lithium ion secondary battery electrode of this embodiment includes a current collector which is a porous metal body, a part of which is impregnated with an electrode composite material containing an electrode active material, and a composite material non-impregnated portion which is not impregnated with the electrode composite material is formed in the other part.

[0037] The battery to which the electrode for lithium ion secondary battery of the present embodiment can be applied can be a battery using an electrolyte in a liquid state, or a battery using a solid electrolyte in a solid state. In addition, the electrode for lithium ion secondary battery of the present embodiment can be applied to the positive electrode, the negative electrode, or both the positive electrode and the negative electrode. In addition, since the positive electrode is smaller than the negative electrode, the risk of the non-impregnated portion of the composite material of the positive electrode contacting the negative electrode is greater, therefore, the electrode for lithium ion secondary battery of the present embodiment is more preferably applied to the positive electrode.

[0038] [Current Collector]

[0039] The current collector constituting the positive electrode 10 and the negative electrode 30 is composed of a metal porous body. The metal porous body has mutually continuous pores, and the electrode composite material containing the electrode active material can be impregnated inside the pores. As the above-mentioned metal porous body, as long as it has mutually continuous pores, there is no particular limitation, and examples thereof include foamed metal, metal mesh, porous metal, punching metal, metal non-woven fabric, etc. having pores formed by foaming. As the metal used for the metal porous body, as long as it has conductivity, there is no particular limitation, and examples thereof include nickel, aluminum, stainless steel, titanium, copper, silver, etc. Among them, as the current collector constituting the positive electrode, foamed aluminum, foamed nickel and foamed stainless steel are preferred, and as the current collector constituting the negative electrode, foamed copper and foamed stainless steel can be preferably used.

[0040] The current collector of the metal porous body has mutually continuous pores inside, and its surface area is larger than the current collector of the metal foil in the past. By using the above-mentioned metal porous body as the current collector, the electrode composite material containing the electrode active material can be impregnated inside the above-mentioned pores. Thus, the amount of active material per unit area of ​​the electrode layer can be increased, and as a result, the volume energy density of the lithium ion secondary battery can be improved. In addition, since the electrode composite material is easy to fix, it is different from the electrode using metal foil as the current collector in the past. When the composite material layer is thickened, it is not necessary to thicken the coating slurry forming the composite material layer. Therefore, it is possible to reduce the adhesive such as the organic polymer compound required for thickening. Therefore, it is possible to increase the capacity per unit area of ​​the electrode, so that the high capacity of the lithium ion secondary battery can be achieved.

[0041] The current collector of the metal porous body is composed of a linear metal portion and a pore portion. The linear metal portion may also have a three-dimensional mesh structure. By using the metal porous body as described above as the current collector, a concave-convex is formed on the surface of the current collector. Thus, when laminating electrodes, especially because the non-impregnated portion of the composite material of the current collector is in contact with other electrodes, a short circuit or contamination may be caused. The lithium ion secondary battery of this embodiment can suppress the short circuit or contamination as described above.

[0042] Hereinafter, the structure of the current collector will be described by taking the positive electrode 10 as an example, but the same structure can be applied to the negative electrode 30. In addition, the following structure can be applied to both the positive electrode 10 and the negative electrode 30. Figure 2 1 is a side cross-sectional view showing the shape of the positive electrode 10 of this embodiment. Figure 2 As shown, the positive electrode 10 includes: a composite material layer 11, which is impregnated with the positive electrode composite material; and a composite material non-impregnated portion, which is composed of a tab narrowing portion 12 and a tab portion 13 and is not impregnated with the positive electrode composite material.

[0043] [Composite material layer]

[0044] The electrode composite material impregnated in the composite material layer 11 contains at least an electrode active material. The electrode composite material applicable to the present embodiment may contain any other components as long as it contains an electrode active material as an essential component. Other components are not particularly limited as long as they are components that can be used when making a lithium ion secondary battery. Examples include electrolytes, conductive additives, adhesives, etc.

[0045] The positive electrode composite material constituting the positive electrode 10 contains at least a positive electrode active material, and may also contain, for example, a solid electrolyte, a conductive aid, a binder, etc. as other components. The positive electrode active material is not particularly limited as long as it can absorb and release lithium ions, and examples thereof 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, LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, sulfur, etc.

[0046] The positive electrode composite material constituting the negative electrode 30 contains at least a negative electrode active material; other components may also contain, for example, a solid electrolyte, a conductive aid, a binder, etc. The negative electrode active material is not particularly limited as long as it can absorb and release lithium ions, and examples thereof 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.

[0047] [Parts not impregnated with composite material]

[0048] The composite material non-impregnated area is a region in the metal porous body where the electrode composite material is not impregnated and where the electrode composite material does not exist. The composite material non-impregnated area is formed by impregnating a part of the metal porous body with the electrode composite material and then pressing the metal porous body. Figure 2The shape shown. By the above pressing, the packing density of the electrode composite material is improved, and the electrode is thinned. The composite material non-impregnated portion is composed of the pole ear narrowing portion 12 and the pole ear portion 13. The pole ear portion 13 is electrically connected to the lead pole ear (omitted from the figure) by welding. The pole ear narrowing portion 12 is formed between the pole ear portion 13 and the composite material layer 11 when the pole ear portion 13 is formed.

[0049] The surface roughness Ra of the portion not impregnated with the composite material is preferably equal to or less than the surface roughness of the composite material layer 11. The surface roughness Ra can be measured as the arithmetic mean roughness Ra measured in accordance with Japanese JIS-B0601:2001.

[0050] The tab narrowing portion 12 is formed between the tab portion 13 and the composite material layer 11. The tab narrowing portion 12 is formed continuously with the composite material layer 11 and the tab portion 13, and is formed so that the thickness becomes thinner as it approaches the tab portion 13 from the composite material layer 11. In addition, the density of the metal part of the porous metal body becomes higher as it approaches the tab portion 13 from the composite material layer 11.

[0051] like Figure 2 As shown, the pole ear portion 13 is formed at a portion of the positive electrode 10 away from the composite material layer 11. Since the electrode composite material is not impregnated in the pole ear portion 13, it is formed to have a thickness thinner than the composite material layer 11 by pressing the metal porous body. In addition, the pole ear portion 13 is formed to have a uniform metal density, wherein the density of the metal portion of the metal porous body is higher than that of the composite material layer 11. The pole ear portion 13 is electrically connected to the lead pole ear (not shown) by welding.

[0052] It is preferred that the surface roughness Ra of at least one of the tab narrowing portion 12 and the tab portion 13 is less than 1 / 10 of the thickness of the composite material layer 11. Thus, it is possible to suppress the generation of short circuits caused by the contact between the tab narrowing portion 12 and the tab portion 13 and other electrodes when laminating electrodes, or the generation of contamination caused by the cutting of the wire of the metal porous body. The thickness of the composite material layer 11 is usually about several hundred μM, so the surface roughness Ra of the tab narrowing portion 12 and the tab portion 13 can be made less than tens of μM by making the surface roughness Ra of the tab narrowing portion 12 and the tab portion 13 less than 1 / 10 of the thickness of the composite material layer 11. Therefore, based on the above, even if the lamination error is taken into account, the tab narrowing portion 12 and the tab portion 13 can be suppressed from contacting with other electrodes, thereby suppressing the generation of short circuits or contamination. In addition to the above, when welding the tab portion 13 to the lead tab, poor welding can be suppressed.

[0053] It is preferred that the surface roughness Ra of at least one of the tab narrowing portion 12 and the tab portion 13 is smaller than the average value of the metal wire diameter of the metal porous body, that is, the average wire diameter. In addition, the metal wire diameter refers to the thickness of the diameter of the linear metal portion of the metal porous body composed of the metal portion and the pore portion. As a result, the metal wire does not protrude onto the surface, and therefore, short circuits or contamination caused by contact between the tab narrowing portion 12 and the tab portion 13 and other electrodes can be reliably prevented. In addition to the above, when welding the tab portion 13 to the lead tab, poor welding can be better suppressed.

[0054] Preferably, at least one of the surface 121 of the tab narrowing portion 12 and the surface 131 of the tab portion 13 is filled with a filler. Thus, the surface roughness Ra of the tab narrowing portion 12 and the tab portion 13 can be easily adjusted. As the above-mentioned filler, at least one of an insulator or a thermal conductor is preferred. By using an insulator as a filler, short circuits can be better suppressed. By using a thermal conductor with high thermal conductivity as a filler, the heat generated in the composite material layer 11 can be efficiently released through the tab narrowing portion 12 and the tab portion 13.

[0055] As the filler, for example, synthetic resins can be cited. There are no particular limitations, and for example, if it is a thermosetting resin, polyimide resins, epoxy resins, silicone resins, polyurethane resins, etc. can be cited; if it is a thermoplastic resin, polyolefin resins, polystyrene resins, fluorine resins, polyvinyl chloride resins, polymethacrylic resins, polyurethane resins, etc. can be cited; if it is a photocurable resin, silicone resins, polymethacrylic resins, polyester resins, etc. can be cited.

[0056] Examples of thermal conductors with high thermal conductivity used as the filler include high thermal conductivity PC (polycarbonate) resin, high thermal conductivity polybutylene terephthalate (PBT) resin, high thermal conductivity polyamide (PA) resin, polyphenylene sulfide (PPS) resin, etc., and further examples include high thermal conductivity silicone materials and high thermal conductivity resin materials with a thermal conductivity of 30 W / mK or more. Preferably, the high thermal conductivity resin material also has electrical insulation properties.

[0057] <Lithium-ion secondary battery>

[0058] As a lithium ion secondary battery to which the lithium ion secondary battery electrode of the present embodiment is applied, a lithium ion secondary battery 1 having a solid electrolyte will be described below as an example.

[0059] like Figure 1 As shown, the lithium ion secondary battery of the present embodiment includes a laminated body in which a positive electrode 10 and a negative electrode 30 as electrodes for the lithium ion secondary battery and a solid electrolyte 20 disposed between the positive electrode 10 and the negative electrode 30 are laminated.

[0060] [Electrolytes]

[0061] The electrolyte used in the lithium ion secondary battery of this embodiment may be a liquid electrolyte solution obtained by dissolving an electrolyte in a non-aqueous solvent, or a solid electrolyte in which the electrolyte is in a solid or gel state. Figure 1 As shown, a solid electrolyte 20 as an electrolyte is laminated between the positive electrode 10 and the negative electrode 30, for example, in a layered form. The solid electrolyte 20 is a layer containing at least a solid electrolyte material. Charge transfer between the positive electrode active material and the negative electrode active material can be performed via the solid electrolyte material.

[0062] The solid electrolyte material is not particularly limited, and examples thereof include sulfide solid electrolyte materials, oxide solid electrolyte materials, nitride solid electrolyte materials, and halide solid electrolyte materials.

[0063] When a liquid electrolyte is used as the electrolyte, there is no particular limitation on the electrolyte dissolved in the non-aqueous solvent, and examples thereof include LiPF6, LiBF4, LiClO4, LiN(SO2CF3), LiN(SO2C2F5)2, LiCF3SO3, LiC4F9SO3, LiC(SO2CF3)3, LiF, LiCl, LiI, Li2S, Li3N, Li3P, Li 10 GeP2S 12 (LGPS), Li3PS4, Li6PS5Cl, Li7P2S8I, Li x PO y N z (x=2y+3z-5, LiPON), Li7La3Zr2O 12 (LLZO), Li 3x La 2 / 3-x TiO3(LLTO), Li 1+x Al x Ti 2-x (PO4)3(0≦x≦1, LATP), Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 , Li 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12, Li 4-2x Zn x GeO4 (LISICON), etc. These may be used alone or in combination of two or more.

[0064] The nonaqueous solvent contained in the electrolyte solution is not particularly limited, and examples thereof include aprotic solvents such as carbonates, esters, ethers, nitriles, sulfones, and lactones. Specifically, there can be mentioned ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dioxane, 1,3-dioxolane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile (AN), propionitrile, nitromethane, N,N-dimethylformamide (DMF), dimethyl sulfoxide, sulfolane, γ-butyrolactone, etc. The above-mentioned can be used alone or in combination of two or more.

[0065] In addition to the above, the lithium-ion secondary battery 1 also has a lead tab and a package. One end of the lead tab is electrically connected by welding with the tab portion of the positive electrode 10 and the negative electrode 30, and the other end extends from the package to form an electrode portion. The lead tab is not particularly limited, and a flexible linear plate-like member such as aluminum or copper can be used. The package contains a laminate including the positive electrode 10, the solid electrolyte 20 and the negative electrode 30, and a portion of the lead tab. The package is not particularly limited, and examples thereof include a laminated battery including a laminated film. In addition, when a liquid electrolyte is used as the electrolyte of the lithium-ion secondary battery, the lithium-ion secondary battery of this embodiment may also include a diaphragm. The diaphragm is located between the positive electrode and the negative electrode. There is no particular limitation on its material or thickness, and well-known diaphragms that can be used in lithium-ion secondary batteries can be applied.

[0066] <Method for producing electrode for lithium ion secondary battery>

[0067] The method for manufacturing an electrode for a lithium-ion secondary battery of the present embodiment includes: an electrode composite material impregnation step, which impregnates a portion of a current collector composed of a metal porous body with the electrode composite material; and a pressing step, which presses the current collector. In addition, before the pressing step, it is preferably included a filler filling step, which fills at least the surface of the composite material non-impregnated portion with a filler.

[0068] [Electrode composite material impregnation process]

[0069] The electrode composite material impregnation step is a step of impregnating a portion of a current collector composed of a metal porous body with the electrode composite material to form a composite material layer. The method of impregnating the metal porous body with the electrode composite material is not particularly limited, and the following methods may be cited: for example, using a plunger-type die coater to apply pressure to impregnate the slurry containing the electrode composite material into the pores of the metal porous body; impregnating the electrode composite material into the pores of the metal porous body by an impregnation method, etc.

[0070] [Filling agent filling process]

[0071] The filler filling process is a process in which the filler is filled into the composite material non-impregnated portion of the metal porous body that is not impregnated with the electrode composite material. The filler filling process is preferably performed before the following pressing process. Thus, usually, the filler is filled in the hole portion to which the pressing pressure is not applied, so the pressing pressure is uniformized and the roughness of the electrode surface is easily reduced. In addition to the above, as the lug portion is approached, the porosity of the lug narrowing portion decreases. Therefore, if the filler filling process is performed after the pressing process, the closer to the lug side, the more difficult it will be to fill the filler, resulting in the inability to uniformly fill the filler. By performing the filler filling process before the pressing process, the filler can be uniformly filled into the lug narrowing portion.

[0072] The method of filling the filler into the composite material non-impregnated portion by the filler filling step is not particularly limited. As with the electrode composite material impregnation step, the following methods can be cited: using a plunger-type die coater to apply pressure to fill the filler into the composite material non-impregnated portion; using an impregnation method to fill the filler into the composite material non-impregnated portion. In addition, before the filler filling step, by pre-thinning the metal wire diameter of the metal porous body in the composite material non-impregnated portion, or pre-increasing the porosity of the metal porous body, the filler can be easily filled into the composite material non-impregnated portion.

[0073] [Pressing process]

[0074] The pressing process is a process in which a current collector impregnated with an electrode composite material in a portion is pressed using a method such as rolling. In the pressing process, it is preferred to press in a manner such that the surface roughness Ra of the composite material non-impregnated portion is less than 1 / 10 of the composite material layer thickness. Furthermore, in the pressing process, it is preferred to press in a manner such that the surface roughness Ra of the composite material non-impregnated portion is less than the average wire diameter of the metal porous body. The above is performed, for example, by adjusting the pressure when pressing the composite material non-impregnated portion of the current collector or the temperature during pressing. In addition to the above, when the pressure and temperature during pressing are fixed, the surface roughness Ra can also be adjusted by selecting the type of filler or adjusting the porosity or wire diameter of the metal porous body in the composite material non-impregnated portion.

[0075] The manufacturing method of the electrode for lithium-ion secondary battery of the present embodiment may also include processes other than the above. For example, the following process may be included to replace the filler filling process: by using chemical substances such as acid or halogen to corrode or dissolve a part of the collector surface, to adjust the surface roughness Ra of the composite material not impregnated. In addition, the following process may also be included: by using an organic solvent or the like to dissolve the filler filled in the pores of the metal porous body and smooth it, to adjust the surface roughness Ra of the composite material not impregnated.

[0076] As mentioned above, although the preferred embodiment of the present invention has been described, the content of the present invention is not limited to the above-mentioned embodiment, and can be modified appropriately.

[0077] Reference numerals

[0078] 1 Lithium-ion secondary battery

[0079] 10 Positive electrode (electrode for lithium-ion secondary battery)

[0080] 11 Composite material layer

[0081] 12 Narrowing part of the tab (part not impregnated with composite material)

[0082] 13. Lug part (part not impregnated with composite material)

[0083] 20 Solid electrolyte

[0084] 30 Negative electrode (electrode for lithium-ion secondary battery)

Claims

1. A lithium ion secondary battery electrode, which is used for a lithium ion secondary battery, The electrode comprises a current collector composed of a porous metal body, and the current collector comprises: a composite material layer impregnated with an electrode composite material containing an electrode active material; and, a composite material non-impregnated portion, which is not impregnated with the aforementioned electrode composite material; The aforementioned porous metal body is composed of a linear metal portion and a pore portion; The composite material non-impregnated portion includes: a pole ear portion having a higher metal density than the composite material layer; and a pole ear narrowing portion formed between the composite material layer and the pole ear portion; The surface roughness Ra of the non-impregnated portion of the composite material is less than the surface roughness Ra of the composite material layer; and The surface roughness Ra of the tab portion and the tab narrowed portion is less than or equal to an average wire diameter of the porous metal body. The average wire diameter is an average value of the thickness of the diameter of the linear metal portion.

2. The lithium ion secondary battery electrode according to claim 1, wherein The surface roughness Ra of the tab narrowing portion is less than 1 / 10 of the thickness of the composite material layer.

3. The lithium ion secondary battery electrode according to claim 1, wherein The surface roughness Ra of the lug portion is 1 / 10 or less of the thickness of the composite material layer.

4. The lithium ion secondary battery electrode according to claim 1, wherein At least the surface of the portion not impregnated with the composite material is filled with a filler.

5. The lithium ion secondary battery electrode according to claim 4, wherein The filler is at least one of an insulator and a thermal conductor.

6. A method for manufacturing an electrode for a lithium ion secondary battery, comprising: an electrode composite material impregnation step of impregnating a portion of a current collector composed of a metal porous body, wherein the metal porous body is composed of a linear metal portion and a pore portion; and A pressing step, in which the collector is pressed so that the surface roughness Ra of the composite material-unimpregnated portion of the collector that is not impregnated with the electrode composite material is less than the average wire diameter of the metal porous body, wherein the average wire diameter is the average value of the thickness of the diameter of the linear metal portion.

7. The method for producing an electrode for a lithium ion secondary battery according to claim 6, wherein: Prior to the pressing step, a filler filling step is included in which a filler is filled into at least the surface of the composite material non-impregnated portion.

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