JP7193239B2 - Manufacturing method of non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery using copper for the negative electrode, and to a non-aqueous electrolyte secondary battery.

Lithium-ion secondary batteries, which are one type of non-aqueous electrolyte secondary battery, have high energy density and high capacity. It is A lithium-ion secondary battery has an electrode body in which a positive electrode plate and a negative electrode plate each having an electrode mixture layer provided on both sides of an electrode core are wound or laminated with a separator interposed therebetween. Aluminum alloy foil or copper foil for secondary battery electrodes is used for the electrode core, and a current collector plate connected to the external electrode terminal is connected to the lead part made of the electrode core at the end of the electrode plate. be done.

Usually, the electrical and mechanical connection between the lead portion and the current collector plate is secured by welding or the like. For example, the negative electrode is welded with the lead portion of the electrode core made of copper and the current collecting plate made of copper being surface-treated. Patent Document 1 describes an example of a non-aqueous electrolyte secondary battery in which a lead portion surface-treated in this way and a current collector plate are welded together.

In the non-aqueous electrolyte secondary battery described in Patent Document 1, an electrode body having a positive electrode and a negative electrode, and a non-aqueous electrolyte are housed in a battery case. The negative electrode includes a current collector (negative electrode terminal), a negative electrode plate (negative electrode current collector) electrically connected to the current collector, and a negative electrode mixture layer (negative electrode active material layer) containing a negative electrode active material. It has The negative electrode plate is a chromate film layer-forming copper foil having a chromate-treated surface, and includes a negative electrode mixture layer forming portion having a negative electrode mixture layer formed thereon, and a negative electrode mixture layer having no negative electrode mixture layer formed thereon. and a layer non-forming portion. The current collector plate is joined to a portion of the negative electrode mixture layer non-formed portion by resistance welding. The surface of the negative electrode mixture layer non-formation portion, at least the portion resistance-welded to the current collector plate and part of the periphery of the resistance-welded portion, is provided with a copper oxide coating layer made of copper oxide. The average thickness of the copper oxide coating layer is 3 nm or more.

Japanese Patent No. 5939436

By the way, the copper oxide coating layer is a necessary layer for resistance welding, but if it grows beyond the thickness suitable for resistance welding, it will increase the battery resistance. Therefore, it is necessary to maintain the proper thickness of the copper oxide coating layer. In this respect, the technique described in Patent Document 1 improves the rust prevention property of the negative electrode plate by chromate treatment, but the copper oxide film that has grown on the current collector plate may increase the battery resistance. There is

Further, Patent Document 1 describes a negative electrode plate in which an organic coating layer is further provided on a copper oxide coating layer. may decrease the welding strength between the negative electrode plate and the current collector plate.

The present invention has been made in view of such circumstances, and a method for manufacturing a non-aqueous electrolyte secondary battery capable of suppressing an increase in battery resistance and maintaining welding strength, and a non-aqueous electrolyte secondary battery. is to provide

A method for manufacturing a non-aqueous electrolyte secondary battery that solves the above problems is a method for manufacturing a non-aqueous electrolyte secondary battery in which an electrode body having a positive electrode and a negative electrode and a non-aqueous electrolyte are accommodated in a battery case. The negative electrode includes a negative electrode current collector plate made of a copper material and a negative electrode plate electrically connected to the negative electrode current collector plate, and the negative electrode plate has a chromate coating having a chromate-treated surface. A mixture layer-forming portion in which a layer-formed copper foil is used as an electrode core, and a negative electrode mixture layer containing a negative electrode active material is formed on the electrode core, and the negative electrode mixture layer is formed on the electrode core. The lead portion is provided with a copper oxide film layer and an organic film layer in this order on the chromate film layer, and the copper material of the negative electrode current collector plate is provided on the lead portion. A copper oxide film forming step of forming a copper oxide film layer having a first thickness on the surface; and a copper sulfide film layer having a second thickness on the surface of the copper oxide film layer formed in the copper oxide film forming step. a step of forming a copper sulfide coating, and a joining step of joining the negative electrode current collector plate to a part of the lead portion of the negative electrode plate through the copper sulfide coating layer by resistance welding.

A non-aqueous electrolyte secondary battery that solves the above problems is a non-aqueous electrolyte secondary battery in which an electrode body having a positive electrode and a negative electrode and a non-aqueous electrolyte are housed in a battery case, the negative electrode comprising: A negative electrode current collector plate made of a copper material and a negative electrode plate electrically connected to the negative electrode current collector plate are provided. The electrode core has a mixture layer forming portion in which a negative electrode mixture layer containing a negative electrode active material is formed on the electrode core, and a lead portion on which the negative electrode mixture layer is not formed on the electrode core. The lead portion is provided with at least a copper oxide film layer and an organic film layer in this order on the chromate film layer, and the negative electrode current collector plate is at least the surface of the copper material. A copper oxide coating layer having a first thickness and a copper sulfide coating layer having a second thickness in this order, and are joined to a part of the lead portion of the negative electrode plate by resistance welding. .

According to such a method or configuration, the growth of the copper oxide coating layer of the negative electrode current collector plate is suppressed by the copper sulfide coating layer. Thereby, an increase in battery resistance due to an increase in the thickness of the copper oxide coating layer can be suppressed.

In addition, since the copper sulfide coating layer suppresses an increase in the thickness of the copper oxide coating layer of the negative electrode current collector plate, the time during which the negative electrode current collector plate can be exposed to the atmosphere is lengthened. Therefore, the labor and cost required for manufacturing the non-aqueous electrolyte secondary battery can be reduced.

In addition, the copper sulfide coating layer has a higher affinity for welding with the organic coating layer of the negative electrode plate than the copper oxide coating layer. Therefore, the peel strength (welding strength) in welding between the negative electrode plate and the negative electrode current collector plate can be maintained by providing the copper sulfide coating layer on the negative electrode current collector plate.

As a preferred method, the step of forming a copper oxide film is heat treatment of the negative electrode current collector plate under a predetermined atmosphere, and the step of forming a copper sulfide film is a treatment of immersing the negative electrode current collector plate in an aqueous sulfide solution. .

According to such a method, it is possible to form a copper oxide coating layer having an appropriate thickness by heat treatment and to form a copper sulfide coating layer having an appropriate thickness by immersion treatment in an aqueous sulfide solution.
As a preferred method, in the copper oxide film forming step, the thickness of the copper oxide film layer of the negative electrode current collector is set to 0.005 μm or more and 0.04 μm or less, and in the copper sulfide film forming step, the negative electrode current collector is The thickness of the copper sulfide coating layer is 0.01 μm or more, and the thickness obtained by adding the thickness of the copper oxide coating layer of the negative electrode current collector and the thickness of the copper sulfide coating layer of the negative electrode current collector is formed to 0.07 μm or less.

As a preferred configuration, the thickness of the copper oxide coating layer of the negative electrode current collector is 0.005 μm or more and 0.04 μm or less, and the thickness of the copper sulfide coating layer of the negative electrode current collector is The thickness is 0.01 μm or more, and the sum of the thickness of the copper oxide coating layer of the negative electrode current collector and the thickness of the copper sulfide coating layer of the negative electrode current collector is 0.07 μm or less.

According to such a method or configuration, it is possible to make the copper oxide coating layer thick enough for resistance welding, and to maintain appropriate weldability while suppressing an increase in battery resistance.
As a preferred method, the thickness of the copper oxide coating layer of the negative current collector is greater than 0.03 μm.

As a preferred configuration, the thickness of the copper oxide coating layer of the negative electrode current collector plate is thicker than 0.03 μm.
Generally, when the thickness of the copper oxide coating layer exceeds 0.03 μm, the weldability deteriorates and the battery resistance increases. In this respect, according to such a method or configuration, due to the presence of the copper sulfide coating layer, appropriate weldability is maintained even if the thickness of the copper oxide coating layer exceeds 0.03 μm, and the battery resistance is reduced. increase is suppressed.

ADVANTAGE OF THE INVENTION According to this invention, while suppressing the increase in battery resistance, welding strength can be maintained.

The schematic of the structure about one Embodiment of a non-aqueous electrolyte secondary battery. FIG. 4 is a schematic diagram showing the cross-sectional structure of the electrode plate group of the same embodiment. FIG. 4 is a cross-sectional view showing the layer structure of the lead portion of the electrode plate and the current collector plate in the same embodiment. The table|surface which shows the relationship between the thickness of a film, weldability, and resistance increase rate in the same embodiment. The graph which shows the relationship between the thickness of a film, weldability, and resistance increase rate in the same embodiment.

A method for manufacturing a non-aqueous electrolyte secondary battery and an embodiment of the non-aqueous electrolyte secondary battery will be described with reference to FIGS. 1 to 5. FIG. In addition, in this embodiment, the secondary battery is a lithium ion secondary battery.

A plurality of secondary batteries of the present embodiment are connected by bus bars to form an assembled battery. The assembled battery is mounted on an electric vehicle or a hybrid vehicle and supplies electric power to an electric motor or the like. A secondary battery is a sealed battery having a rectangular parallelepiped outer shape.

As shown in FIG. 1, a secondary battery 10 includes a rectangular parallelepiped battery case 11 having an opening on the upper side, a lid 12 for sealing the battery case 11, and an electrode body housed inside the battery case 11. 20 and a liquid non-aqueous electrolyte 27 injected into the battery case 11 . The battery case 11 and the lid 12 are made of metal such as aluminum alloy. The secondary battery 10 forms a sealed battery case by attaching a lid 12 to a battery case 11 . The secondary battery 10 also includes a lid 12 and two external terminals 13 for charging and discharging electric power. In this embodiment, in FIG. 1, the external terminal 13 on the left side is a positive external terminal, and the external terminal 13 on the right side is a negative external terminal.

The electrode assembly 20 is formed by flatly winding a positive electrode plate 21, a negative electrode plate 22, and a separator 23 interposed therebetween. The electrode body 20 is multi-layered by being folded back at both ends 26 in the winding direction (winding direction). The electrode assembly 20 has a positive electrode lead portion 21A in which the positive electrode plate 21 protrudes from one end side in a direction perpendicular to the winding direction (winding axis direction), and a negative electrode lead portion 21A in which the negative electrode plate 22 protrudes from the other end side in the direction perpendicular to the winding direction. and a lead portion 22A. The positive electrode lead portion 21A and the negative electrode lead portion 22A are partially compressed, and the external terminals 13 are connected to the compressed portions 21C and 22C of the positive electrode lead portion 21A and the negative electrode lead portion 22A, respectively. A current collector plate 14 connected to is welded.

The separator 23 is a non-woven fabric made of polypropylene or the like for holding the non-aqueous electrolyte 27 between the positive electrode plate 21 and the negative electrode plate 22 . As the separator 23, a porous polymer film such as a porous polyethylene film, a porous polyolefin film, and a porous polyvinyl chloride film, or a lithium ion or ion conductive polymer electrolyte film is used alone or in combination. You can also

(Non-aqueous electrolyte)
The non-aqueous electrolyte 27 is a composition containing a supporting salt in a non-aqueous solvent. Here, as the non-aqueous solvent, one or two selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. More than one species of material can be used. Support salts include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiI 1 or 2 or more lithium compounds (lithium salts) selected from the above can be used.

(Positive plate)
As shown in FIG. 2, the positive electrode plate 21 includes a positive electrode base material 211 as a strip-shaped electrode core, and positive electrode mixture layers 212 and 213 on an inner peripheral surface 211A and an outer peripheral surface 211B of the positive electrode base material 211. It has The positive electrode base material 211 uses a metal foil suitable for a positive electrode, such as a strip-shaped aluminum foil having a predetermined width and a thickness of 15 μm. In addition, the positive electrode substrate 211 has an uncoated portion 211M along one edge in the width direction. Positive electrode mixture layers 212 and 213 are held on both sides of positive electrode substrate 211 except for uncoated portion 211M, forming a mixture layer forming portion coated on positive electrode substrate 211 . Further, the positive electrode substrate 211 has the lead portion 21A of the positive electrode in the uncoated portion 211M. The positive electrode mixture layers 212 and 213 contain a positive electrode active material, and are formed by applying a positive electrode mixture containing the positive electrode active material to the positive electrode substrate 211 .

The positive electrode mixture layers 212 and 213 contain positive electrode active material particles, a conductive material, and a binder. A material that can be used as a positive electrode active material for a lithium ion secondary battery can be used for the positive electrode active material particles. Examples thereof include lithium-nickel-cobalt-manganese-based composite oxides having a layered crystal structure containing Li, Ni, Co, and Mn as constituent metal elements. Lithium transition metal oxides such as LiNiO ₂ (lithium nickelate), LiCoO ₂ (lithium cobaltate), LiMn ₂ O ₄ (lithium manganate), and LiFePO ₄ (lithium iron phosphate) are also included. Here, LiMn ₂ O ₄ has, for example, a spinel crystal structure. Also, LiNiO ₂ or LiCoO ₂ has a layered rock salt structure. Also, LiFePO ₄ has, for example, an olivine structure. LiFePO ₄ with an olivine structure, for example, has particles on the order of nanometers. Also, LiFePO ₄ with an olivine structure can be further coated with a carbon film.

Examples of conductive materials include carbon materials such as carbon powder and carbon fibers. As the conductive material, one selected from such conductive materials may be used alone, or two or more thereof may be used in combination. Carbon powders such as various carbon blacks (eg, acetylene black, oil furnace black, graphitized carbon black, carbon black, graphite, ketjen black) and graphite powders can be used as the carbon powder.

Further, the binder plays a role of binding the positive electrode active material particles and conductive material particles contained in the positive electrode mixture layers 212 and 213 and binding these particles and the positive electrode substrate 211 . A polymer that can be dissolved or dispersed in the solvent used can be used as such a binder. For example, in a positive electrode mixture composition using an aqueous solvent, cellulose-based polymers (carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), etc.), fluorine-based resins (e.g., polyvinyl alcohol (PVA), polytetrafluoroethylene) (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc.), rubbers (vinyl acetate copolymer, styrene-butadiene copolymer (SBR), acrylic acid-modified SBR resin (SBR latex), etc.) A water-soluble or water-dispersible polymer such as is preferably employed. Polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), and the like can be preferably used in the positive electrode mixture composition using a non-aqueous solvent.

For the positive electrode mixture layers 212 and 213, for example, a positive electrode mixture is prepared by mixing the above-described positive electrode active material particles and conductive material with a solvent in a paste (slurry) state, and the positive electrode mixture is applied to the positive electrode base material 211. It is formed by coating, drying and rolling. At this time, both an aqueous solvent and a non-aqueous solvent can be used as the solvent for the positive electrode mixture. Suitable examples of non-aqueous solvents include N-methyl-2-pyrrolidone (NMP). The polymer material exemplified as the binder may be used for the purpose of exhibiting a function as a thickener or other additive for the positive electrode mixture, in addition to the function as a binder.

The mass ratio of the positive electrode active material in the entire positive electrode mixture is preferably 50 wt% or more (typically 50 to 95 wt%), and usually 70 to 95 wt% (eg, 75 to 90 wt%). more preferred. Also, the proportion of the conductive material in the entire positive electrode mixture can be, for example, 2 to 20 wt %, and is usually preferably 2 to 15 wt %. In a composition using a binder, the ratio of the binder to the entire positive electrode mixture can be, for example, 1 to 10 wt%, and usually 2 to 5 wt% is preferable.

(negative plate)
As shown in FIG. 2, the negative electrode plate 22 includes a negative electrode substrate 221 as a strip-shaped electrode core, and negative electrode mixture layers 222 and 223 on an inner peripheral surface 221A and an outer peripheral surface 221B of the negative electrode substrate 221. there is A metal foil suitable for a negative electrode is preferably used for the negative electrode base material 221, and for example, a strip-shaped copper foil having a predetermined width and a thickness of 10 μm is used. In addition, on one side in the width direction of the negative electrode substrate 221, there is an uncoated portion 221M as a mixture layer non-formed portion along the edge. The negative electrode mixture layers 222 and 223 are held on both sides of the negative electrode substrate 221 except for the uncoated portion 221M. The negative electrode mixture layers 222 and 223 contain a negative electrode active material, and are formed by coating the negative electrode base material 221 with a negative electrode mixture containing the negative electrode active material.

The negative electrode mixture layers 222 and 223 contain negative electrode active material particles, a thickener, a binder, and the like. As the negative electrode active material particles, one or more materials conventionally used in lithium ion secondary batteries as negative electrode active materials can be used. For example, a particulate carbon material (carbon particles) at least partially including a graphite structure (layered structure) can be used. Specifically, the negative electrode active material includes, for example, natural graphite, natural graphite coated with an amorphous carbon material, graphite, non-graphitizable carbon (hard carbon), and graphitizable carbon (soft carbon). carbon), or a carbon material in which these are combined.

Moreover, the polymer material exemplified as the binder of the positive electrode mixture layers 212 and 213 can be used as the binder. For example, the binder is composed of at least one of an aqueous polymer including rubbers and a non-aqueous polymer. Examples of aqueous polymers containing rubbers include styrene-butadiene rubber (SBR). Here, the styrene-butadiene rubber is a copolymer containing styrene and 1,3-butadiene, and its copolymerization mode is not limited. Modified SBR obtained by copolymerizing an unsaturated carboxylic acid or an unsaturated nitrile compound may also be used. Other examples of polymers that are dispersed or dissolved in water include polyacrylates (acrylic acid ester homopolymers or copolymers), polyurethanes, and the like. Such polymers may be used singly or in combination of two or more.

For the negative electrode mixture layers 222 and 223, for example, a negative electrode mixture is prepared by mixing negative electrode active material particles and a binder in a solvent in a paste form (slurry form), applied to the negative electrode base material 221, dried, and rolled. It is formed by At this time, both an aqueous solvent and a non-aqueous solvent can be used as the solvent for the negative electrode mixture. Suitable examples of non-aqueous solvents include N-methyl-2-pyrrolidone (NMP). In addition to the function as a binder, the polymer material may also be used for the purpose of exhibiting a function as a thickener or other additives for the positive electrode mixture.

(Lead part)
As shown in FIG. 2, the negative electrode base material 221 has an uncoated portion 221M where the negative electrode mixture layers 222 and 223 are not formed. The negative electrode base material 221 is electrically connected to the negative current collector 14M as a negative current collector, and the current collector 14M is joined to the compressed portion 22C of the negative lead 22A. In this embodiment, the negative electrode is composed of the negative electrode plate 22 and the current collector plate 14M of the negative electrode.

The bonding between the negative electrode lead portion 22A and the negative electrode collector plate 14M will be described with reference to FIG. Hereinafter, the lead portion 22A of the negative electrode, the collector plate 14M of the negative electrode, and the like are simply referred to as the lead portion 22A, the collector plate 14M, and the like.

In the lead portion 22A, at least a chromate coating layer 224, a copper oxide coating layer 225, and an organic coating layer 226 are laminated in this order from the negative electrode base material 221. As shown in FIG. On the other hand, the collector plate 14M is provided with at least a copper oxide coating layer 142 and a copper sulfide coating layer 143 in this order from the copper substrate 141 . Then, the lead portion 22A and the current collector plate 14M are resistance-welded after the organic coating layer 226 of the lead portion 22A and the copper sulfide coating layer 143 of the current collector plate 14M face each other.

First, the negative electrode base material 221 is a so-called chromate film layer formed copper foil, in which a belt-shaped copper foil is used and a chromate film layer 224 is formed on the surface of the copper foil. The chromate coating layer 224 formed on the surface of the negative electrode base material 221 can improve the rust resistance of the negative electrode base material 221 .

The chromate coating layer 224 may be a known one, and can be formed using, for example, chromic acid, sodium dichromate, potassium dichromate, or the like. Typically, the form of precipitation of chromium after the formation of the chromate coating layer is a mixture of Cr(OH) ₃ and Cr ₂ O ₃ and is precipitated in the form of trivalent chromium. Also, the chromic acid solution may be either alkaline or acidic. For example, the average thickness of the chromate coating layer 224 is preferably 1 nm or more and less than 1000 nm, preferably 1.1 nm or more and 10 nm or less, and more preferably 2 nm or more and 5 nm or less.

Since the chromate film layer-formed copper foil is subjected to chromate treatment, the surface of the negative electrode substrate 221 is mixed with chromium oxide, and the chromium oxide has good conductivity, so that current flows easily. Therefore, the negative electrode base material 221 has good conductivity and low contact resistance. Therefore, in the secondary battery 10 of the present embodiment, the surface of the chromate coating layer 224 applied to the surface of the uncoated portion 221M of the negative electrode substrate 221, that is, the compressed portion 22C is formed between the current collector plate 14M and the A copper oxide coating layer 225 made of copper oxide is formed on the joint and part of its periphery. However, the copper oxide coating layer 225 may be formed at least on the surface of the chromate coating layer 224 on the uncoated portion 221M. The copper coating layer 225 may or may not be formed. When the current collecting plate 14M and the lead portion 22A are resistance-welded, the chromate coating layer 224 may be lost at the welded portion.

The average thickness of the copper oxide coating layer 225 is 3 nm or more (typically 150 nm or less), preferably 5 nm or more, and more preferably 10 nm or more. If the average thickness of the copper oxide coating layer 225 is thinner than the above range, the electrical conductivity will be high, so resistance heat generation during welding cannot be expected, and there is a possibility that suitable welding cannot be performed. Therefore, by forming the copper oxide coating layer 225 with an average thickness within the above range, the contact resistance of the joint portion between the current collector plate 14M and the negative electrode substrate 221 and a part of the periphery thereof can be more preferably increased. As a result, it becomes easier to weld the welded portion and a part of its periphery. The method for measuring the average thickness of the copper oxide coating layer 225 is X-ray photoelectron spectroscopy (XPS).

A generally used surface treatment method can be used to form the copper oxide film layer 225 on the surface of the uncoated portion 221M. One example is a treatment method in which the surface is irradiated with physical energy such as plasma irradiation by corona discharge or ultraviolet (UV) irradiation. By performing such a surface treatment, the copper oxide film layer 225 can be formed on the joint portion of the uncoated portion 221M with the current collector plate 14M and part of the periphery thereof. As a result, the contact resistance of the joint portion of the uncoated portion 221M with the collector plate 14M and a part of the periphery thereof can be increased, and the weld between the collector plate 14M and the negative electrode substrate 221 is facilitated.

Further, an organic coating layer 226 may be formed on the copper oxide coating layer 225 of the uncoated portion 221M. Examples of the organic coating layer 226 include those containing sulfide compounds and their decomposition products. Specifically, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₃ C, etc., and their decomposition products.

The average thickness of the organic coating layer 226 is preferably 0.5 nm or more and 3.0 nm or less, preferably 0.5 nm or more and 2.0 nm or less. A method for measuring the average thickness of the organic coating layer 226 is X-ray photoelectron spectroscopy (XPS). When the average thickness of the organic coating layer 226 is within the above range, the organic coating layer 226 is preferably formed on both the negative electrode substrate 221 and the current collector plate 14M. It may be formed on either the material 221 or the collector plate 14M.

(current collector)
As shown in FIG. 1, the collector plate 14 is made of the same metal material as the electrode core material of the positive electrode plate 21 or the negative electrode plate 22 to be connected. The collector plate 14 includes a long plate-like metal plate that electrically connects the external terminal 13 and the positive lead portion 21A, and a long plate-like plate that electrically connects the external terminal 13 and the negative lead portion 22A. It is a metal plate. One of the collector plates 14 is a positive collector plate 14P connected to the positive lead portion 21A, and the other is a negative collector plate 14M connected to the negative lead portion 22A. Therefore, the positive electrode collector plate 14P is made of the same aluminum alloy as the positive electrode substrate 211, and the negative electrode collector plate 14M is made of the same copper material as the negative electrode substrate 221. In this embodiment, the positive electrode is composed of the positive electrode plate 21 and the current collector plate 14P of the positive electrode.

As shown in FIG. 3, the current collector plate 14M has a copper oxide film layer 142 formed on the surface of the copper plate. However, the copper oxide coating layer 142 may be formed at least at the position corresponding to the compressed portion 22C on the uncoated portion 221M and its periphery. When the current collector plate 14M and the lead portion 22A are resistance-welded, the copper oxide coating layer 142 may be lost at the welded portion.

The average thickness of the copper oxide coating layer 142 is the same as the average thickness of the copper oxide coating layer 225, and is 3 nm or more (typically 150 nm or less), preferably 5 nm or more, more preferably 10 nm or more.

If the average thickness of the copper oxide coating layer 142 is thicker than the above range, the electrical conductivity will be low, and although resistance heat will be generated during welding, the battery resistance may increase. Therefore, by forming the copper oxide coating layer 142 with an average thickness within the above range, it is possible to prevent an increase in the battery resistance of the joint portion between the current collector plate 14M and the negative electrode substrate 221 and a portion of the periphery thereof. . As a result, it becomes easier to weld the welded portion and a part of its periphery. The method for measuring the average thickness of the copper oxide coating layer 142 is X-ray photoelectron spectroscopy (XPS).

A generally used surface treatment method can be used to form the copper oxide film layer 142 on the surface of the current collector plate 14M (copper oxide film forming step). That is, as an example, there is a processing method in which the current collecting plate 14M is heated under a predetermined atmosphere. The predetermined atmosphere may be the atmosphere or a gas that promotes oxidation. By performing such a surface treatment, the copper oxide coating layer 142 can be formed on the joint portion of the current collector plate 14M with the uncoated portion 221M and part of the periphery thereof. As a result, the contact resistance of the joint portion of the current collector plate 14M with the uncoated portion 221M and a portion of the periphery thereof can be increased, and the current collector plate 14M and the negative electrode substrate 221 can be easily welded.

During manufacturing, the copper oxide coating layer 142 grows and increases in thickness according to the length of time the current collector plate 14M is exposed to the atmosphere. As a result, the electrical conductivity of the current collector plate 14M is lowered, the contact resistance is increased, and the battery resistance is increased. Therefore, in the secondary battery 10 of the present embodiment, copper sulfide is added to the surface of the copper plate in the compressed portion 21C of the current collector plate 14M and further to the surface of the copper oxide coating layer 142, that is, the joint portion and part of the periphery thereof. A copper sulfide coating layer 143 consisting of is formed.

As a method of forming the copper sulfide coating layer 143 on the surface of the current collector plate 14M, a generally used surface treatment method by sulfurization can be used (copper sulfide coating forming step). As an example, in the sulfurization process, a metal material is immersed and held in molten salt or a sulfide solution in a treatment tank, and electrolysis is performed using the metal material as the anode and the treatment tank as the cathode. There is a treatment method that creates a sulfurized layer on the surface of the material. Further, as an example, the sulfurization treatment may be performed at 200 to 350° C. while flowing a sulfurization gas such as H ₂ S (hydrogen sulfide) gas. By performing such a surface treatment, the copper sulfide coating layer 143 can be formed on the joint portion of the current collector plate 14M with the uncoated portion 221M and part of the periphery thereof. As a result, the contact resistance of the joint portion of the current collector plate 14M with the uncoated portion 221M and a part of its periphery can be increased, and the welding between the negative electrode base material 221 and the current collector plate 14M becomes easier.

(welding)
Then, in the bonding step in the manufacturing method of the secondary battery 10 of the present embodiment, the collector plate 14M is bonded to the compressed portion 22C of the negative electrode plate 22 by welding. Resistance welding is preferably used for this welding. In the joining step, the compressed portion 22C obtained by collecting the uncoated portions 221M near the middle in the stacking direction is welded to the welded portion 14C of the current collector plate 14M. In welding, two electrodes of the welding device are arranged to sandwich the compressed portion 22C and the current collector plate 14M. Then, by pressing one electrode against the other electrode, the compressed portion 22C of the uncoated portion 221M of the negative electrode substrate 221 and the welded portion 14C of the current collector plate 14M of the negative electrode are brought into contact with each other to form resistance. do welding.

Resistance welding uses resistance heat generated by applying an electric current to the material to be welded, so the higher the resistance of the material to be welded, the better the weldability. In the case where only the chromate coating layer 224 is formed, the surface of the uncoated portion 221M is mixed with conductive chromium oxide, and current flows more than the negative electrode substrate 221 without the chromate coating layer 224 formed thereon. Cheap. In addition, the current collector plate 14M is generally subjected to barrel polishing or degreasing treatment to remove foreign matter, and has a smooth surface. Therefore, a large contact area is ensured between the current collector plate 14M and the negative electrode substrate 221, and the contact resistance becomes low, so that resistance heating cannot be expected.

Forming a copper oxide coating layer 225 on at least a portion of the surface of the compressed portion 22C of the uncoated portion 221M on which the chromate coating layer 224 is formed, which is joined to the current collector plate 14M and a portion of the periphery thereof. , the contact resistance between the current collector plate 14M and the negative electrode substrate 221 can be increased. In addition, the contact resistance between the current collector plate 14M and the negative electrode base material 221 is reduced by forming the copper oxide film layer 142 on the connection portion with the uncoated portion 221M and part of the periphery thereof on the current collector plate 14M as well. can be enhanced. As a result, when welding by resistance welding, the current collector plate 14M of the negative electrode and the negative electrode base material 221 generate sufficient heat even if the input voltage is small, so that the welding can be preferably performed. Note that the chromate coating layer 224 is typically lost during the resistance welding.

(Example and Comparative Example)
An example of a specific example and an example of a comparative example will be described below with reference to FIGS. 4 and 5. FIG. List 41 shows examples and comparative examples. In List 41, the second thickness “copper sulfide thickness (μm)” is the thickness of the copper sulfide coating layer 143, and the first thickness “copper oxide thickness (μm)” is the copper oxide coating. is the thickness of layer 142 , where “total thickness (μm)” is the thickness of copper oxide coating layer 142 plus the thickness of copper sulfide coating layer 143 . Further, when the copper sulfide thickness is "0 μm", there is no example, when the copper sulfide thickness is "0.01 μm (10 nm)", Examples 22 to 25 are used, and when the copper sulfide thickness is "0.03 μm (30 nm)". There are Examples 32-35 when In addition, when the copper sulfide thickness is "0 μm", there are Comparative Examples 11 to 17, when the copper sulfide thickness is "0.01 μm", there are Comparative Examples 21 and 26, and when the copper sulfide thickness is "0.03 μm", there are comparisons. There are examples 31 and 36.

The secondary battery 10 was produced by welding the lead portion 22A and the current collector plate 14M according to the following procedure.
<Example 22>
(Negative plate 22)
A negative electrode substrate 221 and one of the negative electrode substrates 221 having a chromate coating layer 224 having an average thickness of 2 nm using a chromium-based trivalent chromium complex on the surface of a band-shaped electrolytic copper foil having a thickness of 10 μm. A negative electrode plate 22 having negative electrode mixture layers 222 and 223 coated on portions other than the ends (uncoated portions 221M) was prepared. Next, the uncoated portion 221M of the negative electrode substrate 221 of the negative electrode plate 22 was irradiated with plasma to form the copper oxide coating layer 225, thereby preparing the negative electrode plate 22 of the secondary battery 10 according to Example 22. . For plasma irradiation, a special high-frequency power supply CT series: CT-0212 manufactured by Kasuga Denki Co., Ltd. is used, and the conveying speed of the electrolytic copper foil conveyed between electrodes connected to the high-frequency power supply is 15 m / min. The applied voltage is 14 kV and the power at this time is 0.5 kW.

(Negative collector plate 14M)
A current collecting plate 14M made of copper with a thickness of 1 mm was prepared. On the current collector plate 14M, a copper oxide film layer 142 of 0.005 μm was formed in a copper oxide film forming step, and then a copper sulfide film layer 143 of 0.01 μm was formed in a copper sulfide film forming step. Therefore, the total thickness is 0.015 μm. Then, the welded portion 14C with the electrode assembly 20 was bent along the compressed portion 22C, which is the uncoated portion 221M gathered at the central portion of the electrode assembly 20. FIG. After that, the welded portion 14C of the current collector plate 14M was pressed so as to have a thickness of 0.6 mm. Then, the current collector plate 14M was subjected to barrel polishing and degreasing treatment to remove foreign matter, and a current collector plate 14M according to Example 22 was manufactured.

(resistance welding)
The compressed portion 22C of the negative electrode plate 22 (negative electrode base material 221) was contacted with the welding portion 14C of the current collector plate 14M, and resistance welding was performed under the following welding power source and welding conditions.

Welding power supply: Resistance welder Nag System Co., Ltd., DDC welder DNWS-5500-4M
Welding conditions: Input voltage 8V, time 6ms, pressure 1.5kN
<Examples 23-25>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 22 except that the thickness of the copper oxide coating layer 142 was different from that in Example 22. Specifically, the thickness of the copper oxide film layer 142 formed in the copper oxide film forming step is 0.01 μm in Example 23, 0.03 μm in Example 24, and 0.04 μm in Example 25. Thus, Example 23 has a total thickness of 0.02 μm, Example 24 has a total thickness of 0.04 μm, and Example 25 has a total thickness of 0.05 μm. Thereafter, a copper sulfide coating layer 143 having a thickness of 0.01 μm was formed in a copper sulfide coating forming step, and resistance welding was performed.

<Comparative Examples 21 and 26>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 22 except that the thickness of the copper oxide coating layer 142 was different from that in Example 22. Specifically, in Comparative Example 21, the thickness of the copper oxide coating layer 142 was 0 μm, that is, it was not provided. be. Therefore, in Comparative Example 21, the total thickness is 0.01 μm, and in Comparative Example 26, the total thickness is 0.07 μm. Thereafter, a copper sulfide coating layer 143 having a thickness of 0.01 μm was formed in a copper sulfide coating forming step, and resistance welding was performed.

<Example 32>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 22 except that the thickness of the copper sulfide coating layer 143 was different from that in Example 22. Specifically, a 0.005 μm copper oxide film layer 142 was formed in the copper oxide film forming process, and then a 0.03 μm copper sulfide film layer 143 was formed in the sulfide film forming process, followed by resistance welding. Therefore, the total thickness is 0.035 μm.

<Examples 33-35>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 32 except that the thickness of the copper oxide coating layer 142 was different from that in Example 32. Specifically, the thickness of the copper oxide film layer 142 formed in the copper oxide film forming step is 0.01 μm in Example 33, 0.03 μm in Example 34, and 0.04 μm in Example 35. Thus, Example 33 has a total thickness of 0.04 μm, Example 34 has a total thickness of 0.06 μm, and Example 35 has a total thickness of 0.07 μm. Thereafter, a copper sulfide coating layer 143 having a thickness of 0.03 μm was formed in a copper sulfide coating forming step, and resistance welding was performed.

<Comparative Examples 31 and 36>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 32 except that the thickness of the copper oxide coating layer 142 was different from that in Example 32. Specifically, in Comparative Example 31, the thickness of the copper oxide coating layer 142 was 0 μm, that is, it was not provided. be. Therefore, in Comparative Example 31, the total thickness is 0.03 μm, and in Comparative Example 36, the total thickness is 0.09 μm. Thereafter, a copper sulfide coating layer 143 having a thickness of 0.03 μm was formed in a copper sulfide coating forming step, and resistance welding was performed.

<Comparative Examples 11 to 17>
The negative electrode collector plate 14M was fabricated in the same manner as in Example 22, except that the step of forming the copper sulfide coating was not performed and the thickness of the copper oxide coating layer 142 was the same as or different from that in Example 22. Specifically, in Comparative Example 11, the thickness of the copper oxide coating layer 142 is 0 μm, that is, it is not provided. The thickness of the copper oxide film layer 142 formed in the copper oxide film forming step was 0.005 μm in Comparative Example 12, 0.01 μm in Comparative Example 13, 0.03 μm in Comparative Example 14, and 0.04 μm in Comparative Example 15. , Comparative Example 16 is 0.05 μm, and Comparative Example 17 is 0.06 μm. Therefore, the total thickness is also 0.005 μm in Comparative Example 12, 0.01 μm in Comparative Example 13, 0.03 μm in Comparative Example 14, 0.04 μm in Comparative Example 15, 0.05 μm in Comparative Example 16, and 0.05 μm in Comparative Example 17. 0.06 μm. After that, resistance welding was performed.

[Resistance increase rate after use]
In Examples 22 to 25, 32 to 35 and Comparative Examples 11 to 17, 21, 26, 31, and 36, the rate of increase in resistance between the negative electrode substrate 221 and the current collecting plate 14M was measured. The rate of increase in resistance is obtained by measuring the ratio of the battery resistance after use to the battery resistance before use when the secondary battery 10 is charged and discharged for a predetermined period of time.

In the measurement, the electrode assembly 20 wound in 60 layers with a width of 30 mm and the current collector plate 14M of the negative electrode are sandwiched between two resistance welding electrodes having a tip area of φ4 mm. Then, the electrical resistance between the electrode assembly 20 and the negative electrode collector plate 14M was measured.

List 41 shows the rate of increase in resistance after use under predetermined conditions as the secondary battery 10 for three cases, ie, when the copper sulfide thickness is 0 μm, when it is 0.01 μm, and when it is 0.03 μm. It shows about In both cases, the thickness of copper oxide of 0.005 μm is defined as 100%.

[Weldability]
In Examples 22 to 25, 32 to 35 and Comparative Examples 11 to 17, 21, 26, 31, 36, the weldability was measured by measuring the welding strength between the negative electrode base material 221 and the current collector plate 14M. was judged. Using a tensile tester, the negative electrode collector plate 14M and the electrode body 20 resistance-welded are fixed to the tensile tester, and the breaking peak strength is measured when the tip of the negative electrode collector plate 14M is grasped and pulled up. did.

In the list 41, the weldability between the lead portion 22A and the current collector plate 14M is appropriate with "○" (circle), with good weldability with "◎" (double circle), and with unsuitable weldability. is indicated by "x" (cross mark).

(Action)
The action of the copper sulfide coating layer 143 of this embodiment will be described.
A copper oxide coating layer 142 is required for resistance welding. This is evident from the list 41 in FIG. 4, in which the comparative examples 11, 21, and 31 with a copper oxide thickness of 0 μm are marked with "x" and have poor weldability. That is, the welding strength is lowered.

As for resistance welding, it is preferable that welding can be performed under welding conditions set to a small current and a short time. In this regard, the thicker the copper oxide coating layer 142, the higher the resistance, so that the welding conditions set as described above do not allow sufficient heat generation and melting, resulting in poor weldability. This reduces the weld strength.

For example, Comparative Examples 15 to 17, 26, and 36 have the copper oxide coating layer 142, but the weldability is not appropriate as indicated by "X" in List 41. At this time, in Comparative Examples 15 to 17 in which the copper sulfide thickness is 0 μm, the weldability is not appropriate if the copper oxide thickness is 0.04 μm or more. On the other hand, when the copper sulfide thickness is 0.01 μm, as shown in Comparative Example 26, when the copper oxide thickness is 0.07 μm or more, the weldability is not suitable. Moreover, when the copper sulfide thickness is 0.03 μm, as shown in Comparative Example 36, when the copper oxide thickness is 0.09 μm or more, the weldability is not suitable.

In other words, compared to Comparative Examples 15 and 16 with a copper sulfide thickness of 0 μm, when the copper sulfide thickness is 0.01 μm, as shown in Examples 22 to 25, the copper oxide thickness is 0.005 μm or more and 0.05 μm or less. Weldability is appropriate even if there is In particular, it is preferable that the copper oxide thickness is 0.005 μm or more and 0.04 μm or less. Furthermore, unlike Comparative Examples 15 to 17, as shown in Examples 24 and 25, weldability is appropriate even when the copper oxide thickness is 0.04 μm or more and 0.05 μm or less.

Moreover, compared with Comparative Examples 15 to 17 in which the copper sulfide thickness was 0 μm, when the copper sulfide thickness was 0.03 μm, the copper oxide thickness was 0.005 μm or more and 0.07 μm or less as shown in Examples 32 to 35. Weldability is appropriate even if In particular, it is preferable that the copper oxide thickness is 0.005 μm or more and 0.06 μm or less. Furthermore, unlike Comparative Examples 15-17, as shown in Examples 33-35, weldability is appropriate even when the copper oxide thickness is 0.04 μm or more and 0.07 μm or less.

That is, by providing the current collector plate 14M with the copper sulfide coating layer 143, the weldability is appropriately maintained even if the thickness of the copper oxide increases. The copper oxide film layer 142 is formed in the copper oxide film forming process, but it also grows depending on the time it is exposed to the atmosphere. Therefore, the range of thickness of copper oxide in which weldability is appropriately maintained is widened, so that the degree of freedom of work in manufacturing the current collector plate 14M can be improved.

Also, corresponding to the appropriate weldability, the rate of increase in resistance after use can be suppressed. For example, in Comparative Examples 15 to 17 in which the weldability is not appropriate, the resistance increase rate after use in List 41 is 120%, 150%, and 160%, exceeding the appropriate resistance increase rate of 110%. not. Comparative Examples 26 and 36, in which the weldability is not appropriate, have resistance increase rates of 120% and 120% after use in List 41, which also exceed 110%, which is not appropriate.

In other words, compared to Comparative Examples 15 and 16 with a copper sulfide thickness of 0 μm, when the copper sulfide thickness was 0.01 μm, the resistance increase rate after use was 105% and 108% as shown in Examples 24 and 25. is appropriate. In addition, compared to Comparative Examples 15 to 17 without the copper sulfide coating layer 143, when the copper sulfide thickness was 0.03 μm, the resistance increase rate after use was 108% as shown in Example 35, which is appropriate. be.

As shown in FIG. 5, the collector plate 14M has a higher resistance increase rate as the copper oxide coating layer 142 becomes thicker. At this time, as indicated by "mark 1" with a total thickness of 0.04 μm, "mark 2" with a total thickness of 0.05 μm, and "mark 3" with a total thickness of 0.07 μm, the current collector plate 14M is formed of the copper oxide coating layer 142. are of the same thickness, the copper sulfide coating layer 143 does not increase its resistance as it becomes thicker. In the example shown in FIG. 5, as the copper sulfide coating layer 143 becomes thicker, the copper oxide coating layer 142 decreases the rate of increase in resistance.

Since the copper sulfide coating layer 143 is formed on the surface of the copper oxide coating layer 142, the growth of the copper oxide coating layer 142 is suppressed. As a result, the thickness of the copper oxide coating layer 142 can ensure appropriate weldability, and the time in which the thickness can be maintained within a range in which the resistance increase rate after use is appropriate is ensured for a long time. As a result, labor and costs in manufacturing can be reduced, and the degree of freedom can be improved.

Also, the copper sulfide coating layer 143 is provided by sulfurization treatment, and is relatively easy to form.
Moreover, the copper sulfide coating layer 143 has a high affinity with the organic coating layer 226 of the lead portion 22A. Due to the high affinity, the weldability between the lead portion 22A and the current collector plate 14M in resistance welding is enhanced, and the weld strength measured by the peel strength is maintained high.

As described above, according to this embodiment, the following effects can be obtained.
(1) The copper sulfide coating layer 143 suppresses the growth of the copper oxide coating layer 142 of the current collector plate 14M. As a result, an increase in battery resistance due to an increase in the thickness of the copper oxide coating layer 142 can be suppressed.

In addition, since the copper sulfide coating layer 143 suppresses an increase in the thickness of the copper oxide coating layer 142 of the current collecting plate 14M, the time during which the current collecting plate 14M can be exposed to the atmosphere during manufacturing is Since the secondary battery 10 is lengthened, the labor and cost required for manufacturing the secondary battery 10 can be reduced.

Moreover, the copper sulfide coating layer 143 has a higher affinity for welding with the organic coating layer 226 of the negative electrode plate 22 than the copper oxide coating layer 142 . Therefore, by providing the current collector plate 14M with the copper sulfide coating layer 143, it is possible to maintain high peel strength (weld strength) in welding between the negative electrode plate 22 and the current collector plate 14M.

(2) It becomes possible to form a copper oxide coating layer 142 having an appropriate thickness by corona discharge and to form a copper sulfide coating layer 143 having an appropriate thickness by immersion treatment in an aqueous sulfide solution or the like.
(3) The thickness of the copper oxide coating layer 142 can be set to allow resistance welding, and appropriate weldability can be maintained while suppressing an increase in battery resistance.

(4) Usually, when the thickness of the copper oxide coating layer exceeds 0.03 μm, the weldability deteriorates and the battery resistance increases. In this regard, due to the presence of the copper sulfide coating layer 143, appropriate weldability is maintained even if the thickness of the copper oxide coating layer 142 exceeds 0.03 μm, and an increase in battery resistance is suppressed.

(Other embodiments)
In addition, the said embodiment can also be implemented in the following aspects.
- In the above-described embodiment, the case where the copper oxide coating layer 142 is formed by heat-treating the current collector plate 14M in a predetermined atmosphere has been exemplified. However, the method is not limited to this, and the method for forming the copper oxide coating layer on the surface of the negative electrode current collector plate may be the same as the method for forming the copper oxide coating layer on the negative electrode substrate. That is, one example is a treatment method in which the surface is irradiated with physical energy such as plasma irradiation by corona discharge or ultraviolet (UV) irradiation.

- In the above-described embodiment, the lead portion 22A has at least the chromate coating layer 224, the copper oxide coating layer 225, and the organic coating layer 226 laminated in this order from the negative electrode base material 221 as an example. However, it is not limited to this, and a layer having a small effect on weldability and resistance increase rate after use may be provided between each layer of the chromate coating layer, the copper oxide coating layer, and the organic coating layer or above and below each layer. .

- In the above-described embodiment, the current collector plate 14M has illustrated the case where at least the copper oxide film layer 142 and the copper sulfide film layer 143 are laminated in order from the copper base material 141 . However, the present invention is not limited to this, and a layer or the like that has little effect on the weldability and the resistance increase rate after use may be provided between each layer of the copper oxide coating layer and the copper sulfide coating layer or above and below each layer.

- The secondary battery 10 may not be mounted on an electric vehicle or a hybrid vehicle. For example, the secondary battery 10 may be mounted in a vehicle such as a gasoline vehicle or a diesel vehicle. The secondary battery 10 may also be used as a power source for mobile objects such as railways, ships, and aircraft, robots, and electrical products such as information processing devices.

DESCRIPTION OF SYMBOLS 10... Secondary battery, 11... Battery case, 12... Lid body, 13... External terminal, 14... Current collector, 14C... Welding part, 14M, 14P... Current collector, 20... Electrode body, 21... Positive electrode plate, 21A... Lead part, 21C... Part, 22... Negative plate, 22A... Lead part, 22C... Part, 23... Separator, 26... End, 27... Non-aqueous electrolyte, 41... List, 141... Copper base material, 142... Oxidation Copper coating layer 143 Copper sulfide coating layer 211 Positive electrode substrate 211A Inner peripheral surface 211B Outer peripheral surface 211M Uncoated portion 212, 213 Positive electrode mixture layer 221 Negative electrode substrate 221A... inner peripheral surface, 221B... outer peripheral surface, 221M... uncoated portion, 222, 223... negative electrode mixture layer, 224... chromate coating layer, 225... copper oxide coating layer, 226... organic coating layer.

Claims (5)

A method for manufacturing a non-aqueous electrolyte secondary battery in which an electrode body having a positive electrode and a negative electrode and a non-aqueous electrolyte are housed in a battery case,
The negative electrode includes a negative electrode current collector plate made of a copper material and a negative electrode plate electrically connected to the negative electrode current collector plate,
The negative electrode plate has a chromate film layer formed copper foil having a chromate-treated surface as an electrode core, and a mixture layer forming part in which a negative electrode mixture layer containing a negative electrode active material is formed on the electrode core; The electrode core has a lead portion on which the negative electrode mixture layer is not formed,
The lead portion is provided with a copper oxide coating layer and an organic coating layer containing a sulfide-based compound and its decomposition products in this order on the chromate coating layer,
a copper oxide film forming step of forming a copper oxide film layer having a first thickness of 0.005 μm or more and 0.04 μm or less on the surface of the copper material of the negative electrode current collector;
a second thickness of 0.01 μm or more on the surface of the copper oxide film layer formed in the copper oxide film forming step, and the thickness of the copper oxide film layer of the negative electrode current collector plate and the thickness of the negative electrode current collector plate; A copper sulfide coating forming step of forming a copper sulfide coating layer having a thickness of 0.07 μm or less by adding the thickness of the copper sulfide coating layer of
and a joining step of joining the negative electrode current collector plate to a part of the lead portion of the negative electrode plate through the copper sulfide coating layer by resistance welding. The step of forming the copper oxide film is heat treatment of the negative electrode current collector plate under a predetermined atmosphere,
2. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein said copper sulfide film forming step is a treatment of immersing said negative electrode current collector plate in a sulfide aqueous solution. 3 . The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1 , wherein the thickness of the copper oxide coating layer of the negative electrode current collector plate is thicker than 0.03 μm. A non-aqueous electrolyte secondary battery in which an electrode body having a positive electrode and a negative electrode and a non-aqueous electrolyte are housed in a battery case,
The negative electrode includes a negative electrode current collector plate made of a copper material and a negative electrode plate electrically connected to the negative electrode current collector plate,
The negative electrode plate has a chromate film layer formed copper foil having a chromate-treated surface as an electrode core, and a mixture layer forming part in which a negative electrode mixture layer containing a negative electrode active material is formed on the electrode core; The electrode core has a lead portion on which the negative electrode mixture layer is not formed,
The lead portion is provided with at least a copper oxide coating layer and an organic coating layer containing a sulfide-based compound and its decomposition products in this order on the chromate coating layer,
The negative electrode current collector plate has, in order from the surface of the copper material, at least a copper oxide coating layer having a first thickness of 0.005 μm or more and 0.04 μm or less and a second thickness of 0.01 μm or more, and and a copper sulfide coating layer having a thickness obtained by adding the thickness of the copper oxide coating layer of the negative electrode current collector plate and the thickness of the copper sulfide coating layer of the negative electrode current collector plate to 0.07 μm or less. and a non-aqueous electrolyte secondary battery joined to a part of the lead portion of the negative electrode plate by resistance welding. The non-aqueous electrolyte secondary battery according to claim 4 , wherein the thickness of the copper oxide coating layer of the negative electrode current collector plate is thicker than 0.03 µm.

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