Electrodes and power storage devices

Abstract

An electrode is provided, comprising a current collector, an electrode composite, a metal plate-like body with a through hole, and an electrode tab, wherein the current collector is a metal porous body, the electrode composite is filled in the gaps of the current collector, the electrode tab is an extension extending from the metal plate-like body, a resin is present in the through hole, and in a plan view, a region forming the through hole of the metal plate-like body is arranged inside the current collector. Furthermore, an electric storage device is provided, comprising the electrode.

Description

Technical Field

[0001] The present invention relates to an electrode and an electric storage device. Background Art

[0002] In the past, lithium-ion secondary batteries have been widely used as power storage devices with high energy density. Lithium-ion secondary batteries have the following structures, for example, a separator is present between a positive electrode and a negative electrode, and an electrolyte is filled. In addition, a fully solid-state battery is also known, which uses an inorganic solid electrolyte instead of an electrolyte.

[0003] Such lithium ion secondary batteries have various requirements depending on their use. For example, when used in automobiles, the volume energy density needs to be further improved. For this purpose, one method is to increase the packing density of the electrode active material.

[0004] As a method for increasing the packing density of electrode active materials, it is proposed to use foamed metal as a current collector constituting the positive electrode and the negative electrode (see Patent Documents 1 and 2). The foamed metal has a mesh structure with uniform pore diameters and a large surface area. Therefore, the gaps in the foamed metal are filled with an electrode composite material containing an electrode active material, thereby increasing the amount of electrode active material per unit area of ​​the electrode.

[0005] [Prior technical literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 7-099058

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 8-329954 Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] Here, when a foamed metal is used as a current collector, the end of the foamed metal is usually compressed by punching or the like, thereby forming an electrode tab.

[0011] However, there is a problem that the volume of the electrode composite material expands due to charge and discharge, so stress is applied to the boundary between the portion of the current collector filled with the electrode composite material and the electrode tab, resulting in cracks, which results in a reduction in the output of the lithium-ion secondary battery. This problem is particularly significant when using negative electrode active materials such as Si and Sn that have a large volume expansion.

[0012] An object of the present invention is to provide an electrode having improved durability.

[0013] [Technical means to solve the problem]

[0014] In one aspect of the present invention, an electrode comprises a current collector, an electrode composite, a metal plate-like body with perforations, and an electrode tab. The current collector is a metal porous body, the electrode composite is filled in the voids of the current collector, the electrode tab is an extension extending from the metal plate-like body, resin is present in the perforations, and in a plan view, a region forming the perforations of the metal plate-like body is arranged inside the current collector.

[0015] A porous metal body filled with the resin may be present in the through-holes.

[0016] Another aspect of the present invention is a power storage device including the above-mentioned electrode.

[0017] (Effects of the Invention)

[0018] According to the present invention, it is possible to provide an electrode with improved durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-sectional view showing an example of the electrode according to the present embodiment.

[0020] Figure 2 It is depicted and Figure 1 A top view of an example of a metal plate-like body and an electrode tab corresponding to an electrode.

[0021] Figure 3 This is a cross-sectional view showing an example of a lithium ion secondary battery according to this embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0023] <Electrode>

[0024] exist Figure 1 An example of an electrode according to this embodiment is shown in FIG. Figure 2 In the picture and Figure 1 An example of a metal plate body and an electrode tab corresponding to an electrode.

[0025] The electrode 10 comprises a current collector 11, an electrode composite material, a metal plate 12 having a through hole 21 (see Figure 2 ) and electrode tab 12A. The current collector 11 is a metal porous body, and the gaps of the current collector 11 are filled with electrode composite. The electrode tab 12A is an extension extending from the metal plate-like body 12, and resin 13 exists in the through-hole 21. When the electrode 10 is viewed from above, the region where the through-hole 21 of the metal plate-like body 12 is formed is arranged inside the current collector 11.

[0026] Since the current collector 11 filled with the electrode composite and the electrode tab 12A exist as separate structures, even if the volume of the electrode composite expands due to charging and discharging of the electrode 10, no cracks will appear at the boundary between the current collector 11 and the electrode tab 12A. As a result, the output stability of the lithium-ion secondary battery is improved.

[0027] Furthermore, since the resin 13 exists in the through hole 21 formed in the metal plate-like body 12 of the electrode 10, the volume expansion of the electrode composite material in the thickness direction can be absorbed.

[0028] In addition, in the electrode 10, the metal plate-like body 12 is arranged in a manner that the area where the perforation 21 is formed is arranged inside the collector 11, but the metal plate-like body 12 can also be arranged in a manner that the area where the perforation 21 is formed is arranged at the upper part or the lower part of the collector 11.

[0029] Electrode 10 may include a metal porous body filled with resin in perforations 21. In this case, the stacking deviation between current collector 11 on the upper side of metal plate 12 and current collector 11 on the lower side of metal plate 12 can be suppressed by the anchoring effect of the metal porous body.

[0030] The porous metal body filled with the resin may be the same as or different from the porous metal body constituting the current collector 11 .

[0031] [Porous Metal]

[0032] The metal porous body is not particularly limited as long as it is a metal porous body in which the electrode composite material or the resin can be filled in the gaps, and examples thereof include foamed metals.

[0033] The foamed metal has a mesh structure and a large surface area. By using the foamed metal as a current collector, the electrode composite material can be filled in the gap of the foamed metal, the electrode active material mass per unit area of ​​the electrode can be increased, and the volume energy density of the secondary battery can be improved. Moreover, the fixation of the electrode composite material is relatively easy, so even if the slurry used to apply the electrode composite material is not thickened, a thick film of the electrode composite material can be formed. Moreover, the adhesive required for the thickening of the slurry can be reduced. Therefore, compared with the case of using metal foil as a current collector, a thick film of the electrode composite material with low resistance can be formed. Therefore, the capacity per unit area of ​​the electrode can be increased, and as a result, it can contribute to the high capacity of the secondary battery.

[0034] As metals constituting the metal porous body, for example, nickel, aluminum, stainless steel, titanium, copper, and silver can be cited. Among these, foamed aluminum is preferred as the metal porous body constituting the positive electrode current collector, and foamed copper and foamed stainless steel are preferred as the metal porous body constituting the negative electrode current collector.

[0035] [Electrode composite materials]

[0036] The electrode composite material includes an electrode active material and may further include other components.

[0037] Examples of other components include a solid electrolyte, a conductive auxiliary agent, and a binder.

[0038] The positive electrode active material contained in the positive electrode composite is not particularly limited as long as it can absorb and release lithium ions, and examples thereof include LiCoO 2 、Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 ) 2 、Li(Ni 6 / 10 Co 2 / 10 Mn 2 / 10 ) 2 、Li(Ni 8 / 10 Co 1 / 10 Mn 1 / 10 ) 2 、Li(Ni 0.8 Co 0.15 Al 0.05 ) 2 、Li(Ni 1 / 6 Co 4 / 6 Mn 1 / 6 ) 2 、Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 ) 2 、LiCoO 4 、LiMn 2 O 4 、LiNiO 2 、LiFePO 4 , lithium sulfide, sulfur, etc.

[0039] The negative electrode active material contained in the negative electrode composite is not particularly limited as long as it can absorb and release lithium ions. Examples thereof include metallic lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, Si, SiO, Sn and carbon materials.

[0040] Examples of the carbon material include artificial graphite, natural graphite, hard carbon, and soft carbon.

[0041] [Metal plate-shaped body]

[0042] The shape of the metal plate-like body is not particularly limited as long as it can collect current, and examples thereof include foil, mesh, and foamed shapes.

[0043] Examples of the metal constituting the metal plate include nickel, aluminum, stainless steel, titanium, and copper. Among these, aluminum is preferred as the metal plate for the positive electrode, and copper is preferred as the metal plate for the negative electrode.

[0044] When the metal plate-like body is a metal foil, a carbon coating may be applied to the area where the metal foil contacts the current collector, or the surface roughness may be roughened to increase the friction coefficient, thereby suppressing the stacking deviation between the current collector on the upper side of the metal foil and the current collector on the lower side of the metal foil.

[0045] The surface area of ​​the metal plate-like body may be larger than that of the current collector. Thus, even if the electrode material expands, current can still be collected, thereby improving the output stability of the lithium ion secondary battery.

[0046] The thickness of the metal plate-like body is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 200 μm or less.

[0047] The cross-sectional shape of the perforation formed in the metal plate-like body is not particularly limited, and examples thereof include a circle and a polygon.

[0048] The ratio of the total cross-sectional area of ​​the perforations on the surface of the metal plate-shaped body to the surface area of ​​the metal plate-shaped body is preferably 1% to 90%, more preferably 5% to 50%.

[0049] The number of the through holes formed in the metal plate-like body may be one or more, and by setting the number to two or more, it is possible to prevent θ deviation.

[0050] Furthermore, when a plurality of perforations are formed in the metal plate-like body, it is preferred that the perforations be formed on diagonal lines on the surface of the metal plate-like body from the viewpoint of preventing θ deviation.

[0051] [Electrode tab]

[0052] The electrode tabs may also be formed by rolling the ends of the metal plate.

[0053] [Resin]

[0054] The resin present in the perforations of the metal plate-like body is not particularly limited as long as it can absorb the volume expansion of the electrode composite material in the thickness direction, and examples thereof include thermosetting resins, thermoplastic resins, and photocurable resins.

[0055] Examples of the thermosetting resin include polyimide-based resins, epoxy-based resins, silicone-based resins, and polyurethane-based resins.

[0056] Examples of the thermoplastic resin include polyolefin resins, polystyrene resins, fluorine resins, polyvinyl chloride resins, polymethacrylic resins, and polyurethane resins.

[0057] Examples of the photocurable resin include silicone-based resins, polymethacrylic resins, and polyester-based resins.

[0058] <Method for producing electrode>

[0059] The method for producing the electrode of the present embodiment is not particularly limited, and a common method in the technical field can be applied.

[0060] As a method for configuring a perforated area for forming an electrode tab inside a collector, the following methods can be listed, for example: after configuring a resin in the perforated hole of the electrode tab, a metal porous body with an electrode composite material filled in the gap is used to clamp the perforated area for forming the electrode tab and crimp and bond it.

[0061] There is no particular limitation on the method of filling the voids of the current collector with the electrode composite material, and examples thereof include the following methods: using a plunger die coater to apply pressure to fill the voids of the current collector with a slurry containing the electrode composite material; and, using an immersion method to impregnate the voids of the current collector with the slurry containing the electrode composite material.

[0062] As another method for filling the gaps of the current collector with the electrode composite material, the following method can be cited: a pressure difference is generated between the surface of the current collector on the side where the electrode composite material is introduced and the surface on the opposite side thereof, and the electrode composite material is infiltrated and filled into the gaps of the current collector by utilizing the pressure difference. At this time, the properties of the introduced electrode composite material are not particularly limited, and it can be a powder of the electrode composite material or a liquid such as a slurry containing the electrode composite material.

[0063] Alternatively, a porous metal body in which cavities are filled with a resin may be disposed in the through-holes of the electrode tabs instead of the resin.

[0064] The method of filling the voids of the metal porous body with the resin is the same as the method of filling the voids of the current collector with the electrode composite material.

[0065] After the electrode tabs are arranged inside the current collector, a common method in the art can be applied. For example, the current collector with the electrode tabs arranged inside is punched to obtain an electrode. At this time, the density of the electrode composite material can be adjusted by punching.

[0066] <Electrical Storage Equipment>

[0067] The power storage device of this embodiment includes the electrode of this embodiment.

[0068] Examples of the power storage device include secondary batteries such as lithium ion secondary batteries and capacitors.

[0069] The lithium ion secondary battery may be a battery having a liquid electrolyte or a battery having a solid or gel electrolyte. Furthermore, the solid or gel electrolyte may be organic or inorganic.

[0070] The electrode of this embodiment may be applied to only the positive electrode, only the negative electrode, or both the positive electrode and the negative electrode.

[0071] Furthermore, when the electrode of the present embodiment is applied to a lithium ion secondary battery, since the volume expansion of the negative electrode active material is large, it is particularly advantageous when the electrode of the present embodiment is applied to the negative electrode.

[0072] [Lithium-ion secondary battery]

[0073] The lithium ion secondary battery of this embodiment includes a positive electrode, a negative electrode, and a separator or a solid electrolyte layer between the positive electrode and the negative electrode. In the lithium ion secondary battery of this embodiment, at least one of the positive electrode and the negative electrode is an electrode of this embodiment.

[0074] In the lithium ion secondary battery of the present embodiment, the positive electrode or negative electrode to which the electrode of the present embodiment is not applied is not particularly limited as long as it can function as the positive electrode or negative electrode of the lithium ion secondary battery.

[0075] In the lithium ion secondary battery of this embodiment, two materials are selected from materials that can constitute electrodes, the charge and discharge potentials of the two materials are compared, the material showing a higher potential is applied to the positive electrode, and the material showing a lower potential is applied to the negative electrode, so that any battery can be constructed.

[0076] When the lithium ion secondary battery of the present embodiment includes a separator, the separator is located between the positive electrode and the negative electrode.

[0077] The separator is not particularly limited, and a known separator applicable to lithium ion secondary batteries can be used.

[0078] exist Figure 3 An example of a lithium ion secondary battery according to this embodiment is shown in FIG. The lithium ion secondary battery 30 is an example in which the electrode 10 is applied to a negative electrode.

[0079] The lithium ion secondary battery 30 includes a positive electrode 32 and an electrode (negative electrode) 10 formed on both sides of an electrode (negative electrode) 10 in this order with a separator 31 interposed therebetween, and an electrode tab 33 formed on the positive electrode 32 .

[0080] The number of electrodes (negative electrodes) 10 and positive electrodes 32 constituting the lithium ion secondary battery 30 is not particularly limited.

[0081] The electrode tab 33 is not particularly limited, and a known electrode tab can be used.

[0082] When the positive electrode 32 is formed by filling the gaps of a porous metal body serving as a current collector with an electrode composite, the electrode tab 33 can be formed by rolling the end of the current collector.

[0083] When the lithium ion secondary battery of the present embodiment includes a solid electrolyte layer, the solid electrolyte layer is located between the positive electrode and the negative electrode.

[0084] The solid electrolyte contained in the solid electrolyte layer is not particularly limited, and any material that can conduct lithium ions between the positive electrode and the negative electrode is sufficient.

[0085] Examples of the solid electrolyte include oxide-based electrolytes and sulfide-based electrolytes.

[0086] Reference numerals

[0087] 10 Electrode (negative electrode)

[0088] 11 Current Collector

[0089] 12 metal plate-shaped body

[0090] 12A electrode lug

[0091] 13 Resin

[0092] 21. Piercing

[0093] 30 Lithium-ion secondary battery

[0094] 31 Diaphragm

[0095] 31 Positive electrode

[0096] 32 Electrode tabs

Claims

1. An electrode comprising a current collector, an electrode composite material including an electrode active material for occluding and releasing lithium ions, a metal plate-like body having a perforation, and an electrode tab, The current collector is a foamed metal. Filling the gaps in the current collector with the electrode composite material. The electrode tab is an extension extending from the metal plate. In the perforations, there is only a resin for absorbing the volume expansion of the electrode composite material in the thickness direction, or there is only a metal porous body filled with the resin. In a plan view, a region where the through-holes of the metal plate-like body are formed is arranged inside the current collector.

2. An electric storage device comprising the electrode according to claim 1.

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