Electricity storage device and method for manufacturing electricity storage device

Abstract

This invention provides an energy storage device and a method for manufacturing the energy storage device. A technique is provided that enables the recycling and easy reuse of negative electrode materials. As one embodiment of the energy storage device disclosed herein, a battery includes a negative electrode (60) comprising a negative current collector (62), a protective region (70), and a negative active material layer (64). The negative current collector (62) comprises copper. The protective region (70) is disposed on the negative current collector (62) and comprises sulfonic acid ions. The negative active material layer (64) is disposed on the protective region (70).

Description

Technical Field

[0001] This disclosure relates to energy storage devices and methods for manufacturing energy storage devices. Background Technology

[0002] Japanese Patent Application Publication No. 2006-331707 discloses a method for recycling a battery having electrodes. The electrodes include an electrode substrate and an active material layer comprising an active substance and a binder resin fixed to the electrode substrate. The active material layer is described as containing an aqueous binder resin. Furthermore, the battery recycling method includes an active material separation step that hydrolyzes the aqueous binder resin by heating the active material layer separated from the electrode substrate with an acidic aqueous solution, thereby separating the active substance from the aqueous binder resin.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-331707 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] When reusing anode materials, the amount of impurities contained in them becomes important. If the amount of impurities in the recovered anode material is high, a purification process becomes necessary during reuse. However, adding a purification process is not preferable from the perspectives of cost and environmental impact. Therefore, there is a need to further develop technologies that can recover easily reusable anode materials.

[0008] Methods for solving problems

[0009] The energy storage device disclosed herein includes a negative electrode comprising a negative current collector, a protective region, and a negative active material layer. The negative current collector comprises copper. The protective region, disposed on the negative current collector, comprises sulfonic acid ions. The negative active material layer is disposed on the protective region. According to this energy storage device, easily reusable negative electrode material can be recovered from the negative electrode.

[0010] The method for manufacturing the energy storage device disclosed herein includes a preparation step and a charging step. In the preparation step, an energy storage device assembly is prepared. The energy storage device assembly includes a negative current collector, a membrane, and a negative active material layer. The negative current collector includes copper. The membrane, disposed on the negative current collector, includes a cyclic sulfonate ester. The negative active material layer is disposed on the membrane. In the charging step, the energy storage device assembly is charged. For example, using this manufacturing method, the aforementioned energy storage device can be manufactured. Attached Figure Description

[0011] Figure 1 is a cross-sectional view schematically showing the configuration of a battery according to one embodiment.

[0012] Figure 2 is a perspective view schematically showing the configuration of an electrode body according to one embodiment.

[0013] Figure 3 is a schematic diagram showing the configuration of the negative electrode according to one embodiment.

[0014] Figure 4 is an enlarged view schematically showing the structure within the dashed box in Figure 3.

[0015] Figure 5 is a flowchart illustrating a battery manufacturing method according to one embodiment.

[0016] Figure 6 is a schematic diagram used to illustrate the structure of a membrane according to one embodiment. Detailed Implementation

[0017] Several embodiments of the technology disclosed herein will be described below with reference to the accompanying drawings. In the drawings, components that perform the same function... The same reference numerals are used to label parts as appropriate. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships. It should be noted that matters necessary for implementing the technology disclosed herein, other than those specifically mentioned in this specification, can be grasped by those skilled in the art based on prior art. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, the following description is not intended to limit this disclosure to the following forms.

[0018] The term "A to B" used in this specification means "above A and below B," encompassing both "above A" and "below B." The term "energy storage device" in this specification refers to a device capable of charging and discharging. Energy storage devices include batteries such as primary batteries, secondary batteries (e.g., non-aqueous electrolyte secondary batteries like lithium-ion batteries, nickel-metal hydride batteries), and capacitors (physical batteries) such as double-layer capacitors. Furthermore, the term "energy storage device assembly" refers to a structure in a mechanically suitable state for assembling the constituent materials of an energy storage device, and may refer to a structure in a state prior to electrochemical activation treatments such as initial charging treatment. The following description uses a lithium-ion secondary battery (hereinafter referred to as "battery") as an example of one embodiment of the energy storage device disclosed herein. Furthermore, the following description is not intended to limit the energy storage device to lithium-ion secondary batteries.

[0019] Furthermore, in the following description, the reference numerals X, Y, and Z in the accompanying drawings represent the direction of the short side of the battery 100, the direction of the long side orthogonal to the short side, and the vertical direction, respectively. However, these directions are merely for the convenience of explanation and do not limit the arrangement of the battery 100. In this specification, "rectangle" can be a concept that includes both a rectangle and a general rectangle with rounded corners.

[0020] Composition of Battery 100

[0021] Figure 1 is a cross-sectional view schematically showing the configuration of a battery 100 according to one embodiment. Figure 2 is a perspective view schematically showing the configuration of an electrode body 20 according to one embodiment. In the configuration shown in Figure 1, the battery 100 includes a casing 10, an electrode body 20, and an electrolyte (not shown). The components will be described below.

[0022] <Shell 10>

[0023] In the configuration shown in Figure 1, the outer casing 10 is the external container for the battery 100. The electrode body 20 and electrolyte are housed within the outer casing 10. The outer casing 10 is a flat, square shape. The outer casing 10 includes a main body 12 with an opening 12h and a sealing plate 14 that plugs the opening 12h. The sealing plate 14 is a rectangular plate-like member (plate). A thin-walled safety valve 30 is provided on the sealing plate 14 to release internal pressure if the internal pressure of the outer casing 10 rises above a predetermined level. An injection port (not shown) for injecting electrolyte is provided on the outer casing 10. The outer casing 10 is made of, for example, a lightweight, thermally conductive metal material such as aluminum.

[0024] <Electrode 20>

[0025] In the configuration shown in Figure 2, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode 50 and a strip-shaped negative electrode 60 are overlapped by a strip-shaped separator 90 and wound in the long side direction (Z direction in Figure 2). The electrode body 20 is flat in shape. The constituent elements of the electrode body 20 will be described below.

[0026] (Positive electrode 50)

[0027] As shown in Figure 2, in this embodiment, the positive electrode 50 is a rectangular sheet. The positive electrode 50 (positive electrode sheet) has a configuration in which a positive electrode active material layer 54 is formed on one or both sides (in this case, both sides) of the elongated positive electrode current collector 52 along the long side direction. The non-formed portion 52a of the positive electrode active material layer (i.e., the portion where the positive electrode active material layer 54 is not formed and the positive electrode current collector 52 is exposed) is formed in a manner that overflows outward from both ends in the winding axis direction of the winding electrode body 20 (i.e., the sheet width direction orthogonal to the long side direction). It should be noted that, in this specification, the term "sheet-shaped" may, for example, mean a thickness of 5 μm to 500 μm.

[0028] As the positive current collector 52, existing and known positive current collectors used in this type of battery can be used. The positive current collector 52 is preferably a sheet or foil made of a metal with good conductivity. Examples of metal materials constituting the positive current collector 52 include aluminum, nickel, titanium, and stainless steel. The positive current collector 52 is preferably aluminum foil.

[0029] There is no particular limitation on the size of the positive current collector 52, which can be appropriately determined according to the battery design. The thickness of the positive current collector 52 is, for example, 5μm to 35μm, preferably 7μm to 20μm.

[0030] In the configuration shown in Figure 2, the positive electrode active material layer 54 is formed in a strip shape along the long side of the positive electrode current collector 52. The positive electrode active material layer 54 contains a positive electrode active material. Conventionally known positive electrode active materials used in this type of battery can be used as the positive electrode active material. Examples of positive electrode active materials include lithium composite oxides and lithium transition metal phosphate compounds. The crystal structure of the positive electrode active material is not particularly limited and can be a layered structure, a spinel structure, an olivine structure, etc.

[0031] As a lithium composite oxide, a lithium transition metal composite oxide containing at least one of Ni, Co, and Mn as a transition metal element is preferred. Examples of lithium composite oxides include lithium nickel-based composite oxides, lithium cobalt-based composite oxides, lithium manganese-based composite oxides, lithium nickel manganese-based composite oxides, lithium nickel cobalt manganese-based composite oxides, lithium nickel cobalt aluminum-based composite oxides, and lithium iron nickel manganese-based composite oxides.

[0032] Furthermore, in this specification, the term "lithium-nickel-cobalt-manganese composite oxide" refers to oxides containing one or more additional elements besides Li, Ni, Co, Mn, and O. Examples of such additional elements include transition metals and typical metallic elements such as Mg, Ca, Al, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, Na, Fe, Zn, and Sn. Additionally, the added elements can be half-metallic elements such as B, C, Si, and P, and non-metallic elements such as S, F, Cl, Br, and I. This also applies to the aforementioned lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-manganese composite oxides, lithium-nickel-manganese composite oxides, lithium-nickel-cobalt-aluminum composite oxides, and lithium-iron-nickel-manganese composite oxides.

[0033] Examples of lithium transition metal phosphate compounds include lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), and lithium manganese iron phosphate.

[0034] These positive electrode active materials can be used alone or in combination of two or more. As a positive electrode active material, lithium nickel cobalt manganese composite oxides are particularly preferred due to their excellent initial resistance and other properties.

[0035] The average particle size (D50) of the positive electrode active material is not particularly limited, but is, for example, 0.05 μm to 25 μm, preferably 1 μm to 20 μm, and more preferably 3 μm to 15 μm. It should be noted that the term "average particle size" in this specification refers to the particle size measured based on laser diffraction. In the particle size distribution of the scattering method, the cumulative frequency of the particle size is 50% of the volume, starting from the side of the smallest particle.

[0036] The positive electrode active material layer 54 may contain components other than the positive electrode active material, such as lithium triphosphate, conductive materials, and binders. Examples of conductive materials include carbon black such as acetylene black (AB), fumed carbon fiber (VGCF), carbon fiber such as carbon nanotubes (CNTs), and other carbon materials (such as graphite). Examples of binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR).

[0037] The content of the positive electrode active material in the positive electrode active material layer 54 (i.e., the content of the positive electrode active material when the total mass of the positive electrode active material layer 54 is set to 100% by mass) is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 85% by mass or more, and the upper limit can be 99% by mass or less. There is no particular limitation on the content of trilithium phosphate in the positive electrode active material layer 54, preferably 0.1% by mass to 15% by mass, more preferably 0.2% by mass to 10% by mass. There is no particular limitation on the content of conductive material in the positive electrode active material layer 54, preferably 0.1% by mass to 20% by mass, more preferably 0.3% by mass to 15% by mass. There is no particular limitation on the content of binder in the positive electrode active material layer 54, preferably 0.4% by mass to 15% by mass, more preferably 0.5% by mass to 10% by mass.

[0038] The average unit area mass of the positive electrode active material layer 54 is, for example, 1 mg / cm². 2 The above is preferably 2 mg / cm³. 2 The above, more preferably 5 mg / cm³ 2 The above. For example, the upper limit of the average mass per unit area of ​​one side of the positive electrode active material layer 54 is 20 mg / cm². 2 The following can be 15 mg / cm³ 2 The following can be 10 mg / cm³ 2 It should be noted that, in this specification, the term "mass per unit area of ​​the active material layer" refers to the mass (solid content) of the active material layer per unit area of ​​the current collector.

[0039] The thickness of the positive electrode active material layer 54 is, for example, 10 μm or more, preferably 20 μm or more. The upper limit of the thickness of each single side of the positive electrode active material layer 54 is, for example, 400 μm or less, preferably 300 μm or less.

[0040] Generally, when disassembling the battery 100, for safety reasons, disassembly is performed at a voltage of 3V or less (e.g., 0V). However, if disassembly is performed at a voltage of 3V or less, copper (Cu) contained in the negative electrode current collector 62 is prone to dissolution. As a result, a large amount of copper impurities remain in the recovered negative electrode active material (negative electrode material). If the battery 100 is reassembled in this state with copper foreign matter residue, there are concerns about reduced safety due to the influence of metal foreign matter, making it difficult to directly use the recovered negative electrode material. In addition, if a purification process is studied to remove copper foreign matter, further costs and the use of chemicals with high environmental impact will occur, which is not preferable. Therefore, the inventors have developed a negative electrode 60 that can recover and easily reuse negative electrode material, as described below.

[0041] (Negative electrode 60)

[0042] As shown in Figure 2, in this embodiment, the negative electrode 60 is a rectangular sheet. The negative electrode 60 (negative electrode sheet) has a structure in which a negative electrode active material layer 64 is formed on one or both sides (in this case, one side) of the elongated negative electrode current collector 62 along the long side direction. The non-formed portion 62a of the negative electrode active material layer (i.e., the portion where the negative electrode active material layer 64 is not formed and the negative electrode current collector 62 is exposed) is formed in a manner that overflows outward from both ends in the winding axis direction of the wound electrode body 20.

[0043] Here, FIG3 is a schematic diagram showing the configuration of the negative electrode 60 according to one embodiment. FIG3 is a cross-sectional view of the rectangular sheet-like negative electrode 60 cut along its short side. FIG4 is an enlarged view schematically showing the configuration within the dashed box in FIG3. As shown in FIG3, the negative electrode 60 includes a negative electrode current collector 62, a protective region 70, and a negative electrode active material layer 64. The constituent elements are described below.

[0044] The negative electrode current collector 62 contains copper (Cu). The copper content in the negative electrode current collector 62 is, for example, 90% by mass or more, preferably 95% by mass or more, and may be 99% by mass or more (for example, 100% by mass) when the total mass of the negative electrode current collector 62 is set to 100% by mass. The negative electrode current collector 62 may contain metallic materials other than copper. Examples of such metallic materials include nickel, titanium, and stainless steel. The negative electrode current collector 62 is preferably a sheet or foil. The negative electrode current collector 62 is preferably copper foil.

[0045] The size of the negative electrode current collector 62 is not particularly limited and can be appropriately determined according to the battery design. The thickness of the negative electrode current collector 62 is, for example, 5μm to 35μm, preferably 6μm to 20μm.

[0046] As shown in Figure 3, a protective region 70 is disposed on the negative electrode current collector 62. The protective region 70 is disposed between the negative electrode current collector 62 and the negative electrode active material layer 64. The protective region 70 is a region independently provided from the negative electrode active material layer 64. In the negative electrode 60, the negative electrode current collector 62, the protective region 70, and the negative electrode active material layer 64 are stacked sequentially.

[0047] In the configuration shown in Figure 3, the protection region 70 is formed in a strip shape along the long side of the negative current collector 62. In the configuration shown in Figure 3, the protection region 70 is arranged in a layered manner on the negative current collector 62. That is, the protection region 70 is arranged in a layered manner on the negative current collector 62.

[0048] Furthermore, in another embodiment, the protection region 70 may not be arranged in a layered form on the negative current collector 62. The protection region 70 may be formed in shapes such as dotted, striped, wavy, banded (ribbed), dotted, or combinations thereof when viewed from above. On the other hand, from the viewpoint of appropriately suppressing the leaching of copper from the negative current collector 62, it is preferable to arrange the protection region 70 in a layered form.

[0049] When the area of ​​the protection region 70 formed on each side of the negative electrode current collector 62 is set to 100%, for example, 50% or more, from the viewpoint of appropriately suppressing the leaching of copper from the negative electrode current collector 62, it is preferably 60% or more, 70% or more, more preferably 80% or more, 90% or more, and particularly preferably 95% or more, 99% or more (which can be 100%).

[0050] The average mass per unit area of ​​the single-sided protection region 70 of the negative electrode current collector 62 is, for example, 0.1 mg / cm³. 2 The above is preferably 0.2 mg / cm³. 2 The above, more preferably 0.5 mg / cm³ 2 The above. For example, the upper limit of the unit area mass of the average single-sided protection region 70 of the negative electrode current collector 62 is 2 mg / cm³. 2 The following can be 1.5 mg / cm³ 2 Below, 1mg / cm 2 It should be noted that the "mass per unit area of ​​the protected area" in this specification refers to the mass (solid content) of the protected area per unit area of ​​the negative electrode current collector.

[0051] Protected region 70 contains sulfonate ions 80. Sulfonate ions 80 can be represented as RSOO. - (Refer to Figure 4). The R mentioned above can be, for example, an alkyl group, a haloalkyl group, or an aryl group. Alkyl and haloalkyl groups can be straight-chain or branched-chain.

[0052] Sulfonate ions 80 may be generated, for example, by the reductive decomposition of cyclic sulfonate esters 82 contained in membrane 72 (described later). That is, sulfonate ions 80 may be sulfonate ions derived from cyclic sulfonate esters 82. Examples of sulfonate ions 80 include sulfonate ions derived from cyclic sulfonate esters 82 such as 1,3-propanesulfonolactone (PS), 1,3-propenesulfonolactone, 1,4-butanesulfonolactone (BS), 1,4-butenesulfonolactone, 2,4-butanesulfonolactone, 1,8-naphthalenesulfonolactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide (DTD), 4-methyl-1,3,2-dioxothiacyclopentane-2,2-dioxide, and methanedisulfonate methylene ester (MMDS). These sulfonate ions 80 may contain only one type or two or more types. In a preferred embodiment, the sulfonate ion 80 comprises a sulfonate ion of at least one cyclic sulfonate selected from 1,3-propanesulfonyl lactone (PS), 1,3,2-dioxane-2,2-dioxide (DTD), and methane disulfonate methylene ester (MMDS). From the viewpoint of reducing the amount of residual copper in the recovered negative electrode material, 1,3-propanesulfonyl lactone (PS) is particularly preferred. Furthermore, the protection region 70 may further include additives such as binders, provided that it does not significantly impair the effects of this disclosure.

[0053] Although there are no particular limitations, the formula weight of sulfonate ion 80 can be, for example, 50 or more, or 100 or more. The upper limit of the formula weight of sulfonate ion 80 can be, for example, 1000 or less, 500 or less, or 300 or less.

[0054] The thickness of the protective region 70 is, for example, 0.01 μm to 1 μm. From the viewpoint of appropriately preventing the protective region 70 from becoming a resistive layer, it is preferably 0.01 μm to 0.5 μm, and more preferably 0.01 μm to 0.1 μm. The protective region 70 is formed, for example, by reducing and decomposing the film 72, and therefore can be thinly provided on the negative electrode current collector 62. Such a thin protective region 70 is preferred from the viewpoint that it is difficult to increase the resistance of the battery 100.

[0055] The concentration of sulfonic acid ions 80 in the protection region 70 is not particularly limited as long as the effects of the disclosed technology are achieved. The concentration of sulfonic acid ions 80 in the protection region 70 is, for example, 500 ppm or more, and preferably 1000 ppm or more, more preferably 2000 ppm or more, from the viewpoint of suitably reducing the residual amount of copper in the negative electrode material. The upper limit of the concentration of sulfonic acid ions 80 in the protection region 70 is, for example, 10000 ppm or less, and can be 5000 ppm or less. Furthermore, when the protection region 70 contains two or more types of sulfonic acid ions 80, the concentration of the sulfonic acid ions 80 is set as the sum of their concentrations. Additionally, "ppm" here may refer to the concentration relative to the total mass of the protection region 70. The concentration of sulfonic acid ions 80 in the protection region 70 can be quantified, for example, by performing LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) analysis on the pulverized material (powder) of the protection region 70. A commercially available apparatus can be used as the LA-ICP-MS. This measurement can be performed, for example, according to the device's instruction manual.

[0056] Furthermore, the determination of sulfonic acid ions 80 in the protected region 70 can be carried out, for example, as described below. First, the potential of the negative electrode 60 is set below 1.0V (Li / Li + The battery 100 was disassembled, and the negative electrode 60 was removed. Then, the negative electrode active material layer 64 was removed from the removed negative electrode 60, and the surface of the negative electrode current collector 62 (copper foil) was analyzed by X-ray photoelectron spectrometry (XPS). In this analysis, the presence of sulfur (S) was confirmed on the negative electrode current collector 62, and it was determined that sulfonic acid ions 80 were present in the protected region 70.

[0057] In the configuration shown in Figure 2, the negative electrode active material layer 64 is formed in a strip shape along the long side of the negative electrode current collector 62. The negative electrode active material layer 64 is disposed on the protective region 70. The negative electrode active material layer 64 contains a negative electrode active material. As the negative electrode active material, conventionally known negative electrode active materials used in this type of battery can be used. Examples of negative electrode active materials include carbon materials such as graphite, hard carbon, and soft carbon. The graphite can be natural graphite or artificial graphite, and the graphite can be amorphous carbon-coated graphite coated with an amorphous carbon material.

[0058] There is no particular limitation on the average particle size (median diameter: D50) of the negative electrode active material, for example, it is 0.1 μm to 50 μm, preferably 1 μm to 25 μm, and more preferably 5 μm to 20 μm.

[0059] The negative electrode active material layer 64 may contain components other than the negative electrode active material. Examples include adhesives and conductive materials. Examples of adhesives include polyvinylidene fluoride (PVDF), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and polyacrylic acid (PAA). CMC functions as a tackifier. Examples of conductive materials include carbon black such as acetylene black, carbon fibers, and carbon nanotubes (CNTs).

[0060] The content of the negative electrode active material in the negative electrode active material layer 64 (i.e., the content of the negative electrode active material when the total mass of the negative electrode active material layer 64 is set to 100% by mass) is preferably 90% by mass or more, more preferably 95% by mass or more, and the upper limit can be 99% by mass or less. The content of the binder in the negative electrode active material layer is preferably 0.1% by mass to 8% by mass, more preferably 0.5% by mass to 5% by mass. The content of the conductive material in the negative electrode active material layer 64 is preferably 0.01% by mass to 3% by mass, more preferably 0.05% by mass to 1% by mass.

[0061] The average unit area mass of the negative electrode active material layer 64 is, for example, 1 mg / cm³. 2 The above is preferably 2 mg / cm³. 2 The above, more preferably 5 mg / cm³ 2 That's all. On the other hand, the upper limit of the average unit area mass of the negative electrode active material layer 64 on one side is, for example, 20 mg / cm². 2 The following can be 15 mg / cm³ 2 Below, 10mg / cm 2 the following.

[0062] The thickness of the negative electrode active material layer 64 is, for example, 10 μm to 400 μm, preferably 20 μm to 300 μm.

[0063] When the battery 100 is dismantled, the residual amount of copper in the recovered negative electrode material is preferably less than 550 ppm, more preferably less than 500 ppm, less than 400 ppm, even more preferably less than 200 ppm (e.g., less than 170 ppm), and particularly preferably less than 100 ppm (e.g., less than 80 ppm, less than 50 ppm). It should be noted that "ppm" here may refer to the concentration relative to the total mass of the negative electrode material. The same applies to the test examples described later.

[0064] (Block 90)

[0065] As shown in Figure 2, in this embodiment, the partition 90 is a rectangular sheet. Examples of partition 90 (partition sheet) include porous sheets (membranes) made of resins such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide. This porous sheet can be a single-layer structure or a multi-layered structure (e.g., a three-layer structure with PP layers stacked on both sides of a PE layer). A heat-resistant layer (HRL) can be provided on the surface of the partition 90.

[0066] The thickness of the partition 90 is not particularly limited, for example, it is 5μm to 50μm, preferably 10μm to 30μm. The air permeability of the partition 90 obtained by the Göller test method is not particularly limited, but preferably 350 seconds / 100cc or less.

[0067] Electrolyte

[0068] The electrolyte is typically a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt (electrolyte salt). As the non-aqueous solvent, organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones used in the electrolyte of this type of battery can be used without particular limitation. Among these, carbonates are preferred, and specific examples include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), fluoromethyl difluoromethyl carbonate (F-DMC), and difluorotrifluoromethyl carbonate (TFDMC). Such non-aqueous solvents can be used alone or in combination of two or more. As one example, the non-aqueous solvent may contain only carbonates. As another example, the non-aqueous solvent contains carbonates and esters such as methyl acetate.

[0069] As the supporting salt, lithium salts such as LiPF6, LiBF4, and lithium bis(fluorosulfonyl)imide (LiFSI) are preferably used (LiPF6 is preferred). The concentration of the supporting salt is preferably 0.7 mol / L to 1.3 mol / L.

[0070] Furthermore, non-aqueous electrolytes may contain components other than those mentioned above, provided they do not significantly impair the effectiveness of this disclosure, such as film-forming agents like vinylene carbonate (VC) and oxalic acid complexes; gas generators like biphenyl (BP) and cyclohexylbenzene (CHB); and various additives like tackifiers.

[0071] In the configuration shown in Figure 1, the positive terminal 42 and the negative terminal 44 are disposed on the sealing plate 14. The positive terminal 42 is an external connection terminal on the positive electrode side. Here, the positive terminal 42 is electrically connected to the non-formed portion 52a of the positive active material layer of the electrode body 20 via a positive current collector plate 42a. The positive terminal 42 is preferably made of metal, for example, more preferably aluminum or an aluminum alloy. The positive current collector plate 42a may be made of conductive metals such as aluminum, aluminum alloy, nickel, or stainless steel. The negative terminal 44 is an external connection terminal on the negative electrode side. Here, the negative terminal 44 is electrically connected to the non-formed portion 62a of the negative active material layer of the electrode body 20 via a negative current collector plate 44a. The negative terminal 42 is preferably made of metal, for example, more preferably copper or a copper alloy. The negative current collector plate 44a may be made of conductive metals such as copper, copper alloy, nickel, or stainless steel.

[0072] <Manufacturing Method of Battery 100>

[0073] The manufacturing method of the battery 100 according to this embodiment will be described below. FIG. 5 is a flowchart illustrating the manufacturing method of the battery 100 according to one embodiment. FIG. 6 is a schematic diagram illustrating the structure of the membrane 72 according to one embodiment. Furthermore, the following description of the manufacturing method is not intended to limit the manufacturing method of the battery 100 to the methods described below. Additionally, the order of the steps described below can be appropriately changed. Moreover, other processes may be added as needed in addition to the steps described below.

[0074] As shown in Figure 5, the manufacturing method of the battery 100 according to this embodiment includes a preparation step S1 and a charging step S2. The following describes each step.

[0075] (Preparation process S1)

[0076] In this process, a battery assembly is prepared comprising a negative electrode 60, which includes a negative electrode current collector 62, a film 72, and a negative electrode active material layer 64. The negative electrode 60 can be manufactured, for example, by the following method. In this embodiment, the method for manufacturing the negative electrode 60 includes a preparation step, a first forming step, and a second forming step.

[0077] It should be noted that the term "slurry" in this specification refers to a mixture in which some or all of the solid components are dispersed in a dispersion medium, including so-called "paste" and "ink".

[0078] First, a negative electrode current collector 62 containing copper is prepared (preparation process). Specifically, a negative electrode current collector 62 as described in the "Structure of Battery 100" section is prepared.

[0079] Next, a film 72 is formed on one or both sides (in this case, one side) of the prepared negative electrode current collector 62 (first forming step). The film 72 can also be referred to as the precursor of the protective region 70.

[0080] Specifically, firstly, a slurry for membrane formation is prepared. In preparing the slurry, a specified amount of cyclic sulfonate 82 is added to a specified amount of solvent, and the mixture is stirred using a stirring device or similar means until dissolved. Examples of cyclic sulfonate 82 include 1,3-propanesulfonolactone (PS), 1,3-propenesulfonolactone, 1,4-butanesulfonolactone (BS), 1,4-butenesulfonolactone, 2,4-butanesulfonolactone, 1,8-naphthalenesulfonolactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide (DTD), 4-methyl-1,3,2-dioxothiacyclopentane-2,2-dioxide, and methanedisulfonate methylene ester (MMDS). These cyclic sulfonate 82s can be used alone or in combination of two or more. In a preferred embodiment, the cyclic sulfonate comprises at least one selected from 1,3-propanesulfonyl lactone (PS), 1,3,2-dioxothiacyclopentane-2,2-dioxide (DTD), and methane disulfonate methylene (MMDS). Commercially available products can be used as examples of these cyclic sulfonates. Additionally, solvents such as ethanol, water, and acetone can be used.

[0081] There are no particular limitations; the molecular weight of cyclic sulfonate 82 can be, for example, 50 or more, or 100 or more. The upper limit of the molecular weight of cyclic sulfonate 82 can be, for example, 1000 or less, 500 or less, or 300 or less.

[0082] From the viewpoint of forming a low-resistivity thin film, the concentration of the cyclic sulfonate 82 in the film-forming slurry is preferably set to a low concentration. When the total mass of the film-forming slurry is set to 100%, the concentration of the cyclic sulfonate 82 in the film-forming slurry is, for example, 20% or less, preferably 10% or less, and more preferably 5% or less. The lower limit of the concentration of the cyclic sulfonate 82 in the film-forming slurry is, for example, 1% or more, and can be 2% or more. Furthermore, when the film-forming slurry contains two or more cyclic sulfonates 82, the concentration of the cyclic sulfonate 82 is set to their combined value. In addition, the film-forming slurry may further contain additives such as binders, provided that it does not significantly impair the effects of this disclosure.

[0083] As the stirring device, conventionally known stirring devices used in this application can be used without particular limitations. While not particularly limited, the viscosity of the film-forming slurry can, for example, be set to 0.1 mPa. s~50mPa s. This viscosity can be measured, for example, using a commercially available rotational viscometer at 25°C.

[0084] The film-forming slurry prepared above is applied to a predetermined area of ​​the prepared negative electrode current collector 62. This coating can be performed using a gravure coater, a notched wheel coater, a slot coater, a die coater, a spin coater, or a spray dryer. The coated material is then dried at a specified temperature (e.g., 40°C to 90°C). This forms the film 72.

[0085] The thickness of the film 72 formed above is, for example, 0.1 μm to 2 μm, preferably 0.5 μm to 1 μm. The thickness of the film 72 formed above is, for example, 0.1 μm to 5 μm, but from the viewpoint of suitably preventing the protective region 70 formed after reduction decomposition from becoming a resistive layer, it is preferably 0.1 μm to 3 μm, more preferably 0.1 μm to 2 μm.

[0086] In this embodiment, the membrane 72 is formed in a strip shape along the long side of the negative electrode current collector 62. The membrane 72 is arranged in a layered manner on the negative electrode current collector 62. That is, the membrane 72 is arranged in a layered form on the negative electrode current collector 62.

[0087] Furthermore, in another embodiment, the film 72 may not be disposed on the negative electrode current collector 62 in a layered manner. For example, when viewed from above, the film 72 may be formed in the form of dots, strips, waves, bands (ribs), dashed lines, or combinations thereof. On the other hand, from the viewpoint of preferably suppressing the leaching of copper from the negative electrode current collector 62, it is preferable to arrange the film 72 in a layered manner.

[0088] When the area of ​​the film 72 formed on each single side of the negative electrode current collector 62 is set to 100%, for example, it is 50% or more. From the viewpoint of preferably suppressing the leaching of copper from the negative electrode current collector 62, it is preferably 60% or more, 70% or more, more preferably 80% or more, 90% or more, and particularly preferably 95% or more, 99% or more (which can be 100%).

[0089] The average mass per unit area of ​​the film 72 on one side of the negative electrode current collector 62 is, for example, 0.1 mg / cm³. 2 The above is preferably 0.2 mg / cm³. 2 The above, more preferably 0.5 mg / cm³ 2 The above. For example, the upper limit of the average mass per unit area of ​​the film 72 on one side of the negative electrode current collector 62 is 2 mg / cm³. 2 The following can be 1.5 mg / cm³ 2 Below, 1mg / cm 2 It should be noted that, in this specification, the term "mass per unit area of ​​the membrane" refers to the mass (solid content) of the membrane per unit area of ​​the negative electrode current collector.

[0090] Next, a negative electrode active material layer 64 is formed on the membrane 72 formed in the first formation step (second formation step).

[0091] Specifically, firstly, a slurry for forming the negative electrode active material layer is prepared. In preparing the slurry, for example, the negative electrode active material, binder, thickener, and dispersion medium are mixed using a mixing device. While not particularly limited, the proportions of each material can be varied, for example, when the total mass of the negative electrode active material, binder, and thickener is set to 100% by mass, the negative electrode active material can be set to 90% to 99% by mass, the binder to 0.1% to 0.5% by mass, and the thickener to 0.1% to 0.5% by mass. The negative electrode active material, binder, and thickener can be substances described in the corresponding section of <Structure of Battery 100>. The proportion of the dispersion medium can be set to, for example, 10 to 40 parts by mass when the total mass of the negative electrode active material, binder, and thickener is set to 100 parts by mass. N-methyl-2-pyrrolidone (NMP) can be used as a dispersion medium, for example. From an operational point of view, the solid content of the slurry for forming the negative electrode active material layer is preferably adjusted to 60% or less, and more preferably to 50% or less. The lower limit of the solid content of the slurry for forming the negative electrode active material layer is, for example, 30% or more, and may be 40% or more.

[0092] As a mixing device, conventionally known mixing devices used in this application can be used without particular limitations. While not particularly limited, the viscosity of the slurry for forming the negative electrode active material layer can, for example, be set to 10 mPa. s~500mPa s. This viscosity can be measured, for example, using a commercially available rotational viscometer at 25°C.

[0093] The slurry for forming the negative electrode active material layer prepared above is applied to the protective area 70 formed in the second forming step. This coating can be performed using a gravure coater, a notched wheel coater, a slot coater, a die coater, a spin coater, or a spray dryer. The coated material is then dried at a specified temperature (e.g., 40°C to 90°C). This forms the negative electrode active material layer 64.

[0094] Then, the laminate of the negative electrode current collector 62, the protective region 70, and the negative electrode active material layer 64 prepared above is pressed. This pressing can be carried out using a press or the like. Although there are no particular limitations, the pressing pressure of the press can be set to, for example, 10 MPa to 100 MPa. As the press, conventionally known presses used in this application can be used without particular limitations.

[0095] As mentioned above, it is possible to produce a negative electrode 60.

[0096] The negative electrode 60 and the positive electrode 50, fabricated using conventional methods, are overlapped via a separator 90, wound together, and pressed under a specified pressure. This yields an electrode body 20 with a flat shape. Next, a sealing plate 14 with a positive terminal 42 and a negative terminal 44 is prepared. Then, a positive current collector 42a and a negative current collector 44a are respectively mounted on the positive terminal 42 and the negative terminal 44. The non-formed portion 56 of the positive active material layer of the electrode body 20 is then electrically connected to the positive current collector 42a. Additionally, the non-formed portion 62a of the negative active material layer of the electrode body 20 is electrically connected to the negative current collector 44a. Finally, the opening 12h of the outer casing body 12 is plugged using the sealing plate 14, and the area around the opening 12h is joined. This yields a battery assembly.

[0097] (Charging process S2)

[0098] In this process, the battery pack prepared in the preparation step S1 is charged. This process is typically the initial charge of the battery pack. The charging step S2 can be performed, for example, by connecting an external power source between the positive terminal 42 and the negative terminal 44 of the battery pack, until the voltage between the terminals reaches a predetermined threshold. The battery pack is preferably charged to a depth of charge (SOC) of, for example, 1% or more, more preferably to 2% or more, and even more preferably to 5% or more. The charging rate can be set to, for example, 0.01C to 1C (preferably 0.1C to 0.5C). The current value can be set to, for example, 1V to 5V (preferably 1V to 4.5V). Charging can be done once, or, for example, it can be repeated two or more times while discharging. This process can be performed, for example, at room temperature (around 25°C ± 10°C).

[0099] Using the charging process S2 described above, the cyclic sulfonate 82 shown in FIG. 6 is reduced and decomposed into sulfonic acid ions 80 shown in FIG. 4. As a result, a protective region 70 containing sulfonic acid ions 80 is generated from the membrane 72 containing the cyclic sulfonate 82.

[0100] As described above, battery 100 can be obtained.

[0101] As described above, the battery 100 according to this embodiment includes a negative electrode 60, which includes a negative electrode current collector 62, a protective region 70, and a negative electrode active material layer 64. The negative electrode current collector 62 contains copper. In this case, copper is easily dissolved from the negative electrode current collector 62 during the disassembly of the battery 100. Consequently, a large amount of copper impurities easily remain in the recovered negative electrode material, which is undesirable. In the battery 100, the negative electrode active material layer 64 is disposed on the protective region 70. Furthermore, the protective region 70 contains sulfonic acid ions 80. In the battery 100, the protective region 70 is provided between the negative electrode current collector 62 and the negative electrode active material layer 64, so that even if copper dissolves from the negative electrode current collector 62, copper ions cannot reach the negative electrode active material layer 64. The protective region 70 functions as a region to suppress copper dissolution during over-discharge because the electrostatic bonding force between sulfonic acid ions 80 and the metal is strong, even if copper ions dissolve from the negative electrode current collector 62. Therefore, for example, when disassembling the battery 100, even if discharged to 0V, the negative electrode 60 can be removed with reduced copper content in the negative electrode active material layer 64. Thus, easily reusable negative electrode material can be recovered. The protective region 70 can also be called a copper ion trapping region. Furthermore, the protective region 70 containing sulfonic acid ions 80 has low resistance, which is preferable from the viewpoint that the resistance value of the battery 100 is unlikely to increase. The battery 100 with this configuration can be manufactured, for example, using the manufacturing method described above.

[0102] In a preferred embodiment, the sulfonate ion 80 comprises at least one selected from propane sulpholactone sulfonate, sulfonate from 1,3,2-dioxothiacyclopentane-2,2-dioxide, and sulfonate from methane disulfonate methylene sulfonate. Based on these sulfonate ions 80, the aforementioned effects can preferably be obtained.

[0103] In addition, each sulfonate ion can be generated by the reduction and decomposition of propane sulcolone, 1,3,2-dioxothiacyclopentane-2,2-dioxide, and methane disulfonate, respectively.

[0104] In a preferred embodiment, the protective region 70 (film 72) is arranged in layers on the negative electrode current collector 62. With this configuration, the aforementioned effects can preferably be obtained.

[0105] In a preferred embodiment, the protection region 70 (film 72) is configured to cover the entire area of ​​the negative electrode current collector 62. With this configuration, the aforementioned effects can be preferably obtained.

[0106] Battery 100 suppresses the swelling of the negative electrode during repeated charging and discharging, thus exhibiting low reaction force. Furthermore, battery 100 has a high capacity. Battery 100 can be used in various applications. Preferred applications include power supplies for driving electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). Additionally, battery 100 can be used as a battery for small energy storage devices. Battery 100 can also be used, typically in the form of a battery pack consisting of multiple batteries connected in series and / or parallel.

[0107] [Experimental Example]

[0108] The following describes test examples related to the technology disclosed herein. Furthermore, the content of the test examples described below is not intended to limit the technology disclosed herein.

[0109] 1. Fabrication of the experimental battery

[0110] (Experimental Example 1)

[0111] First, 1,3-propanesulfonyl lactone (PS) was dissolved in ethanol to prepare a film-forming slurry. The concentration of PS in the film-forming slurry was set to 5%. Next, with an 8 μm thick copper foil fixed in a spin coater, the prepared film-forming slurry was dropped onto it, and a 1 μm thick film was formed by spin coating by driving the spin coater. Then, the formed film was dried at a temperature above 80°C. In this way, a film was formed on the negative electrode current collector.

[0112] Next, graphite (as the negative electrode active material), styrene-butadiene rubber (SBR) (as the binder), and carboxymethyl cellulose (CMC) (as the tackifier) ​​were mixed with ion-exchanged water at a mass ratio of negative electrode active material:SBR:CMC = 99:0.5:0.5 to prepare a slurry for forming the negative electrode active material layer. This slurry was then coated in strips onto the surface of the formed film, dried, and pressed to fabricate the negative electrode sheet. The unit area mass of the negative electrode active material layer was set to 10 mg / cm³. 2 .

[0113] LiNi will be used as the positive electrode active material 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (LNCM), AB as a conductive material, and PVDF as a binder were mixed with NMP at a mass ratio of LNCM:AB:PVDF = 92:5:3 to prepare a positive electrode slurry. This slurry was then coated in strips onto both sides of a 15 μm thick aluminum foil, dried, and pressed to fabricate the positive electrode sheet.

[0114] As a separator, a product with a 4μm thick HRL (high-density layer) formed on a porous polyolefin sheet (20μm thick) of PP / PE / PP three-layer structure was prepared. Then, an electrode body was fabricated by sandwiching the two sides of a positive electrode sheet with a negative electrode sheet between two of the prepared separator sheets. At this time, the HRL of the separator was aligned with the positive electrode sheet.

[0115] A mixed solvent containing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 30:30:40 was prepared. Lithium bis(oxalate)borate was dissolved in this mixed solvent at a concentration of 1.0% by mass, and LiPF6, as the electrolyte salt, was dissolved at a concentration of 1.0 mol / L. This yielded a non-aqueous electrolyte.

[0116] Terminals were mounted on the electrode body fabricated above, and the electrode body, along with a non-aqueous electrolyte, was housed in a laminated housing and sealed. Then, in a constant-current bath at 25°C, the initial charge was performed at a constant current of 0.1C until 4.25V. During this charge, the potential of the negative electrode was below 1.0V during the initial charge up to 4.25V (Li / Li + Therefore, the thin film on the copper foil is reduced to form a protective region containing sulfonic acid ions from PS. Thus, the test battery involved in Test Example 1 is obtained.

[0117] (Experimental Example 2)

[0118] Except that 1,3,2-dioxothiacyclopentane-2,2-dioxide (DTD) was used instead of PS, the test battery involved in Test Example 2 was fabricated in the same manner as in Test Example 1. Furthermore, in Test Example 2, the thin film on the copper foil was reduced by the aforementioned initial charge, forming a protective region containing sulfonic acid ions from DTD.

[0119] (Experimental Example 3)

[0120] Except that methyl methane disulfonate (MMDS) was used instead of PS, the test battery described in Test Example 3 was fabricated in the same manner as in Test Example 1. Furthermore, in Test Example 3, the thin film on the copper foil was reduced by the aforementioned initial charge, forming a protective region containing sulfonic acid ions from MMDS.

[0121] (Experimental Example 4)

[0122] Except that no protective area was provided on the negative current collector, the test battery involved in Test Example 4 was manufactured in the same manner as in Test Example 1.

[0123] (Experimental Example 5)

[0124] Except that maleic anhydride (MA) was used instead of PS, the test battery described in Test Example 5 was fabricated in the same manner as in Test Example 1. Furthermore, in Test Example 5, the thin film on the copper foil was reduced by the initial charge described above, forming a protective region containing -COO- bonds from MA.

[0125] 2. Activation of the test battery

[0126] The test batteries described above were discharged at a constant current of 0.1C until 2.5V. Then, they were charged at a constant current-constant voltage of 0.1C until 4.25V, and then charged at a constant voltage until the current reached 1 / 50C, which was considered the full charge state. Next, they were aged at 60°C for 12 hours. Then, they were discharged at a constant current of 0.1C until 2.5V. This activated the test batteries for each example. Following this activation process, after activation, they were subjected to constant current-constant voltage charge-discharge cycles from 0.1C to 2.5V (with the constant voltage cutoff at 1 / 50C), and the discharge capacity at this point was designated as the initial capacity.

[0127] 3. Recycling of negative electrode materials

[0128] In the test batteries prepared above, a current of 0.1C was applied until 1.0V was reached, and the batteries were left to stand for one day. Then, the test batteries were disassembled, the negative electrode was removed, washed with water, and the active material layer of the negative electrode was peeled off. Since the washing liquid contained graphite from the active material layer of the negative electrode, it was filtered to recover the graphite. The recovered material was dried at a temperature above 100°C to obtain graphite powder.

[0129] 4. Evaluation of negative electrode materials

[0130] The recovered graphite powder was subjected to inductively coupled plasma (ICP) luminescence analysis to quantify the residual Cu content. A Hitachi High Technology Science & Technology Corporation PS3520UVDDII was used as the analytical apparatus. The analysis was performed according to the apparatus's instruction manual. The results are shown in the corresponding columns of Table 1. Furthermore, in this experiment, when the amount of copper in the recovered graphite powder was less than 550 ppm (preferably 500 ppm or less), it was evaluated as an appropriate reduction in the amount of copper in the negative electrode material.

[0131] 5. Evaluation of the IV resistance of the test battery

[0132] In the test batteries involved in the examples prepared above, the initial capacity was set to 100% SOC, and the batteries were charged in a constant temperature bath at 25°C with a charging current of 0.3C until the depth of charge (SOC) reached 50%. Under this condition, the batteries were charged for 10 seconds each at currents of 0.1C, 0.2C, and 0.5C in a constant temperature bath at -10°C. Then, the voltage of each battery was measured, and the current values ​​and battery voltages were plotted to determine the IV characteristic during charging. The IV resistance during charging was determined from the slope of the resulting straight line. The results are shown in the corresponding columns of Table 1. It should be noted that the charging IV resistance (initial resistance) values ​​are recorded as a ratio relative to Test Example 4.

[0133] Table 1

[0134]

[0135] As shown in Table 1, it was confirmed that in the test batteries of Test Examples 1 to 3, which had a protective region containing sulfonic acid ions provided on the negative electrode current collector, the Cu content in the graphite powder was lower than that in Test Example 4, which did not have a protective region provided on the negative electrode current collector, and in Test Example 5, which had a protective region on the negative electrode current collector containing sulfonic acid ions (specifically, the -COO- region).

[0136] Furthermore, as shown in Table 1, it was confirmed that in the test batteries of Test Examples 1 to 3, which have a protective region containing sulfonic acid ions provided on the negative electrode current collector, the increase in charging resistance IV was appropriately suppressed compared with that of Test Example 5, which has a protective region containing sulfonic acid ions (specifically, the -COO- region) provided on the negative electrode current collector.

[0137] The embodiments of the technology disclosed herein have been described above. However, the above description is merely illustrative and does not limit the scope of the claims. The technology described in the claims includes technical solutions that involve various modifications and alterations to the specific examples illustrated in the above description.

[0138] For example, in the above embodiment, the battery 100 includes a wound electrode body as an electrode body 20, but is not limited thereto. In other embodiments, the electrode body 20 may include a stacked electrode body in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked.

[0139] For example, in the above embodiment, the battery 100 is a flat square shape, but it is not limited to this. In other embodiments, the battery 100 may be a cylindrical battery or a battery with a stacked casing.

[0140] For example, in the above embodiment, the battery 100 includes a liquid electrolyte as the electrolyte, but is not limited to this. In other embodiments, the battery 100 may include a gel electrolyte or a solid electrolyte instead of a liquid electrolyte.

[0141] For example, in the above embodiment, battery 100 is a lithium-ion secondary battery, but it is not limited to this. In other embodiments, battery 100 may be a nickel-metal hydride battery or a sodium-ion secondary battery.

[0142] For example, in the above embodiment, the protected region 70 contains sulfonic acid ions 80, which may exist, for example, in a state bound to copper ions. Additionally, in addition to sulfonic acid ions 80, cyclic sulfonate esters 82 may also be present in the protected region 70.

[0143] For example, in the above embodiment, a protective region 70 containing sulfonic acid ions 80 is formed by reducing and decomposing the membrane 72 containing cyclic sulfonate ester 82. On the other hand, in another embodiment, a slurry containing sulfonic acid ions 80 can be coated on the negative electrode current collector 62 to form a protective region 70 containing sulfonic acid ions 80.

[0144] For example, in the above embodiment, a protective region 70 is directly disposed on the negative current collector 62, but this is not a limitation. In another embodiment, other layers may be disposed between the negative current collector 62 and the protective region 70, as long as they do not impede the effect of the technology disclosed herein.

[0145] For example, in the above embodiment, the negative electrode active material layer 64 is directly disposed on the protected region 70, but this is not a limitation. In another embodiment, other layers may be disposed between the protected region 70 and the negative electrode active material layer 64, as long as they do not impede the effect of the technology disclosed herein.

[0146] As described above, the following are examples of specific solutions to the technology disclosed herein.

[0147] Item 1:

[0148] An energy storage device includes a negative electrode comprising: a negative electrode current collector comprising copper, a protective region comprising sulfonic acid ions disposed on the negative electrode current collector, and a negative electrode active material layer disposed on the protective region.

[0149] Item 2:

[0150] According to the energy storage device of claim 1, wherein the sulfonate ion is a sulfonate ion of a cyclic sulfonate selected from at least one of 1,3-propanesulfonyl lactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide, and methane disulfonate.

[0151] Item 3:

[0152] According to item 1 or 2, the energy storage device wherein the protection region is arranged in layers on the negative current collector.

[0153] Item 4:

[0154] The energy storage device according to any one of items 1 to 3, wherein the protection area is configured comprehensively over a defined area on the negative current collector.

[0155] Item 5:

[0156] A method for manufacturing an energy storage device includes: a preparation step of preparing an energy storage device assembly, the energy storage device assembly including a negative electrode, the negative electrode including: a negative electrode current collector containing copper, a membrane containing a cyclic sulfonate disposed on the negative electrode current collector, and a negative electrode active material layer disposed on the membrane; and a charging step of charging the energy storage device assembly.

[0157] Item 6:

[0158] According to the method for manufacturing an energy storage device as described in item 5, the cyclic sulfonate is at least one selected from 1,3-propanesulfonyl lactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide, and methane disulfonate.

[0159] Item 7:

[0160] The method for manufacturing an energy storage device according to item 5 or 6, wherein the membrane is arranged in layers on the negative electrode current collector.

[0161] Item 8:

[0162] The method for manufacturing an energy storage device according to any one of claims 5 to 7, wherein the membrane is configured comprehensively over a defined area on the negative current collector.

[0163] Explanation of reference numerals in the attached figures

[0164] 10. Outer shell

[0165] 12. Outer shell body

[0166] 14 Sealing board

[0167] 20 Electrode Body

[0168] 30 Safety valve

[0169] 42 Positive extremes

[0170] 42a Positive Current Collector

[0171] 44 Negative extremes

[0172] 44a Negative Current Collector

[0173] 50 Positive electrode (positive electrode plate)

[0174] 52 Positive current collector

[0175] 52a Non-forming portion of the positive electrode active material layer

[0176] 54 Positive electrode active material layer

[0177] 60 Negative electrode (negative electrode plate)

[0178] 62 Negative current collector

[0179] 62a Non-forming portion of the negative electrode active material layer

[0180] 64 Negative Electrode Active Material Layer

[0181] 70 protected areas

[0182] 72 membrane

[0183] 80 sulfonic acid ions

[0184] 82 Cyclic sulfonates

[0185] 90. Partition (partition plate)

[0186] 100 batteries

Claims

1. An energy storage device comprising a negative electrode, the negative electrode comprising: a negative electrode current collector comprising copper, a protective region comprising sulfonic acid ions disposed on the negative electrode current collector, and a negative electrode active material layer disposed on the protective region.

2. The energy storage device according to claim 1, wherein, The sulfonate ion is a sulfonate ion from at least one cyclic sulfonate selected from 1,3-propanesulfonyl lactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide, and methane disulfonate methylene ester.

3. The energy storage device according to claim 1 or 2, wherein, The protection area is arranged in layers on the negative electrode current collector.

4. The energy storage device according to claim 1 or 2, wherein, The protection area is configured to cover a defined region on the negative current collector.

5. A method for manufacturing an energy storage device, comprising: a preparation step of preparing an energy storage device assembly, the energy storage device assembly including a negative electrode, the negative electrode including: a negative electrode current collector comprising copper, a membrane comprising a cyclic sulfonate disposed on the negative electrode current collector, and a negative electrode active material layer disposed on the membrane; and a charging step of charging the energy storage device assembly.

6. The method for manufacturing the energy storage device according to claim 5, wherein, The cyclic sulfonate is selected from at least one of 1,3-propanesulfonyl lactone, 1,3,2-dioxothiacyclopentane-2,2-dioxide, and methane disulfonate.

7. The method for manufacturing the energy storage device according to claim 5 or 6, wherein, The membrane is arranged in layers on the negative electrode current collector.

8. The method for manufacturing the energy storage device according to claim 5 or 6, wherein, The membrane is configured throughout a defined area on the negative electrode current collector.

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