JP2013251048A - Nonaqueous electrolyte secondary battery, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery having weld strength with less variation and no voltage drop failure after a negative electrode collector is welded to a negative electrode terminal.SOLUTION: In this nonaqueous electrolyte secondary battery, an electrode body including a positive electrode and a negative electrode and a nonaqueous electrolyte are housed in a battery case, and the negative electrode includes the negative electrode terminal and the negative electrode collector 22. The negative electrode collector 22 is composed of a negative electrode active material layer forming part 24 and a negative electrode active material layer non-forming part 23, and a chromate film forming copper foil the surface of which is chromated is used as the negative electrode collector 22. The negative electrode terminal is joined to a part of the negative electrode active material layer non-forming part 23. Also, a copper oxide coating layer 28 made of a copper oxide is formed on at least the joined portion to the negative electrode terminal on the surface of the negative electrode active material non-forming part 23 and a part of the periphery thereof.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

  Lithium ion secondary batteries and other non-aqueous electrolyte secondary batteries are smaller, lighter, and have higher energy density and superior output density than existing batteries. For this reason, in recent years, it is also preferably used as a so-called portable power source for personal computers and portable terminals, and a vehicle driving power source for hybrid vehicles (HV).

  This type of non-aqueous electrolyte secondary battery is constructed by housing an electrode body including a positive electrode and a negative electrode and a non-aqueous electrolyte (typically a non-aqueous electrolyte) in a battery case. The positive electrode and the negative electrode are electrode mixture layers (specifically, active materials that can reversibly occlude and release charge carriers (typically lithium ions) on the corresponding positive and negative current collectors (specifically, Are each provided with a positive electrode mixture layer and a negative electrode mixture layer.

  For example, in a lithium ion secondary battery which is a typical example of a non-aqueous electrolyte secondary battery, the positive electrode is a positive electrode current collector made of an aluminum foil, and a lithium composite such as lithium cobaltate provided on the surface of the positive electrode current collector. The negative electrode is composed of a negative electrode current collector made of copper foil and a negative electrode active material composed of carbon or the like provided on the surface of the negative electrode current collector. Is done.

  By the way, the said copper foil used as a negative electrode electrical power collector of a lithium ion secondary battery or a nickel hydride battery may be utilized in the state by which the surface was rust-proofed. As an example of this rust prevention treatment, a chromate treatment using a chromium compound-based solution typified by chromic anhydride may be mentioned. For example, in Patent Document 1, in a negative electrode current collector for a lithium ion secondary battery using a rolled copper foil as a constituent material, the rolled copper foil is characterized in that a chromium-based film is formed on the surface thereof. . And it is disclosed that the elution of copper at the time of overcharge is effectively prevented and a negative electrode current collector for a lithium ion secondary battery free from problems such as an increase in cost is provided. Patent Document 2 discloses a copper foil for a lithium ion secondary battery current collector that has a good balance between adhesion with a negative electrode active material, ultrasonic weldability with a copper foil or a tab terminal, and rust prevention. In order to provide, it is disclosed that at least a part of the surface of the copper foil is treated with a silane coupling agent (hereinafter also referred to as “silane coupling treatment”). Patent Document 3 discloses that an electrolytic copper foil is subjected to chromate treatment, and an organic film is further formed on the chromate layer by silane coupling treatment.

JP 2004-63344 A JP 2011-23303 A JP 2008-184657 A

  However, the surface of the copper foil constituting the negative electrode current collector subjected to the above-described chromate treatment is mixed with copper oxide and chromium oxide, and resistance to heat generation cannot be expected due to the high conductivity of chromium oxide. . Therefore, the problem that the weldability at the time of resistance welding a negative electrode collector and a negative electrode terminal falls generate | occur | produces.

  Moreover, since the silane coupling agent mentioned above reacts with the OH group present on the surface of the copper foil of the negative electrode current collector to form a film, the film tends to be uneven depending on the state of the copper foil, and is unreacted. This causes a problem that the silane coupling agent tends to remain on the surface of the copper foil. Furthermore, the lithium ion secondary battery using the negative electrode plate subjected to the silane coupling treatment is deteriorated in the welding strength and the adhesion between the negative electrode active material and the negative electrode current collector in an environment where it is used for a long time. There is also a problem that reliability and battery characteristics are deteriorated due to the above. This problem is that the Si element present in the silane coupling agent is alloyed with copper, so that the copper foil of the negative electrode current collector becomes brittle. As a result, in addition to the decrease in welding strength, the negative electrode active material and the negative electrode current collector It is thought that the adhesiveness with is lowered.

  Therefore, the present invention has been created to solve the above-described problems, and has an object to obtain a non-aqueous electrolyte secondary battery having strong welding strength with little variation and no poor voltage drop. A nonaqueous electrolyte secondary battery capable of realizing the object is provided.

  In order to achieve the above object, the present invention provides a non-aqueous electrolyte secondary battery having the following configuration. That is, the nonaqueous electrolyte secondary battery according to the present invention is a nonaqueous electrolyte secondary battery in which an electrode body including a positive electrode and a negative electrode and a nonaqueous electrolyte are accommodated in a battery case. The negative electrode includes a negative electrode terminal and a negative electrode current collector electrically connected to the negative electrode terminal. The negative electrode current collector is composed of a negative electrode active material layer forming part in which a negative electrode active material layer containing a negative electrode active material is formed and a negative electrode active material layer non-forming part in which the negative electrode active material layer is not formed, In addition, a chromate film layer-formed copper foil whose surface is chromated is used as the negative electrode current collector. The negative electrode terminal is bonded to a part of the negative electrode active material layer non-forming portion. A copper oxide coating layer made of copper oxide is formed on the surface of the negative electrode active material layer non-formation portion, at least at the junction with the negative electrode terminal and a part of the periphery thereof. .

  According to the non-aqueous electrolyte secondary battery having such a configuration, the rust prevention property of the negative electrode current collector can be improved by using the chromate film layer-formed copper foil whose surface is chromated in the negative electrode current collector. it can. In addition, since the chromate film layer-formed copper foil is subjected to chromate treatment, the surface of the negative electrode current collector is mixed with chromium oxide as described above, and the conductivity of the chromium oxide is good. Current is easy to flow. Further, since the negative electrode terminal is usually subjected to barrel polishing or degreasing treatment to remove foreign substances, the surface thereof is typically smooth. Therefore, the contact area between the negative electrode current collector and the negative electrode terminal is large, and the negative electrode current collector has good conductivity, so that the contact resistance is low. As a result, there is a possibility that the welding strength during welding is reduced. Therefore, as in a non-aqueous electrolyte secondary battery having such a configuration, at least on the surface of the negative electrode active material layer non-formation portion, at least a junction portion with the negative electrode terminal and a part of the periphery thereof are oxidized with copper oxide. By forming the copper coating layer, it is possible to increase the contact resistance, and as a result, welding with high strength between the negative electrode terminal and the negative electrode current collector is realized.

  Moreover, in one preferable aspect of the nonaqueous electrolyte secondary battery disclosed herein, the static friction coefficient of the negative electrode active material layer non-forming portion is 0.6 or more (typically 1.0 or less). It is characterized by. According to such a configuration, the static friction coefficient of the negative electrode active material layer non-forming portion is set to the above level, so that the contact resistance between the negative electrode terminal and the negative electrode current collector and the peripheral contact resistance thereof are more preferable. As a result, it becomes easier to weld the welded portion and a part of the periphery thereof more suitably.

  In another preferred embodiment of the nonaqueous electrolyte secondary battery disclosed herein, the copper oxide coating layer has an average thickness of 3 nm or more (typically 150 nm or less). According to such a configuration, by forming the copper oxide film layer with the average thickness, it is possible to more suitably increase the contact resistance between the negative electrode terminal and the negative electrode current collector and a part of the periphery thereof, As a result, it becomes easier to weld the welded portion and a part of the periphery thereof more suitably.

  In another preferred embodiment of the nonaqueous electrolyte secondary battery disclosed herein, an organic rust preventive coating layer derived from at least one compound belonging to triazoles is formed on the upper layer of the copper oxide coating layer. It may be. Thus, by forming the organic rust preventive coating layer further on the copper oxide coating layer, the organic rust preventive coating layer is a metal (typically copper) constituting the negative electrode current collector. Therefore, the rust prevention property of the negative electrode current collector can be improved.

In another preferred embodiment of the nonaqueous electrolyte secondary battery disclosed herein, resistance welding is used for joining the negative electrode terminal and a part of the negative electrode active material layer non-forming portion. In resistance welding, welding is performed using resistance heat generated by passing an electric current through the material to be welded. Therefore, the higher the resistance of the material to be welded, the better the weldability. When only the chromate film layer is formed, the surface of the negative electrode active material non-formation portion of the negative electrode current collector is mixed with chromium oxide, and since the chromium oxide is conductive, the chromate film layer is not formed. Current flows more easily than negative electrode current collector. Further, the negative electrode terminal is usually subjected to barrel polishing or degreasing treatment to remove foreign matters, and the surface thereof is smooth. Therefore, when resistance welding is performed between the negative electrode terminal and the negative electrode current collector, the contact area between the negative electrode terminal and the negative electrode current collector is increased, so that the contact resistance is reduced and resistance heating cannot be expected.
However, in the non-aqueous electrolyte secondary battery having such a configuration, at least a portion of the surface of the negative electrode active material layer non-molded portion of the negative electrode current collector on which the chromate film layer is formed and the junction with the negative electrode terminal By forming the copper oxide coating layer on a part of the periphery, the contact resistance between the negative electrode terminal and the negative electrode current collector can be increased. As a result, when welding by resistance welding (typically, the chromate film layer of the welded part may be lost during the welding), the negative electrode terminal and the negative electrode current collector are sufficient even when the input voltage is small. Therefore, it can be suitably welded.

  In another preferred embodiment of the nonaqueous electrolyte secondary battery disclosed herein, the chromate film layer is present in at least a part of the negative electrode active material layer forming portion. By forming the chromate film layer on at least a part of the surface of the negative electrode active material forming portion, it is possible to improve rust prevention.

  Moreover, this invention provides the manufacturing method of the following nonaqueous electrolyte secondary batteries as another side surface for implement | achieving the objective mentioned above. That is, this is a method for manufacturing a nonaqueous electrolyte secondary battery in which an electrode body including a positive electrode and a negative electrode and an electrolyte are accommodated in a battery case. The method includes preparing a negative electrode current collector having a negative electrode active material layer forming portion including a negative electrode active material layer, a negative electrode active material layer non-forming portion not including the negative electrode active material layer, and a negative electrode terminal. And bonding the negative electrode terminal to a part of the negative electrode active material layer non-forming portion. In the bonding step, as the negative electrode current collector, a chromate film layer-formed copper foil that has been subjected to a chromate treatment in advance is used, and at least the portion where the negative electrode active material layer is not formed is preliminarily made of copper oxide. A copper oxide coating layer is formed. And the said negative electrode terminal is welded to the part in which this copper oxide film layer was formed, It is characterized by the above-mentioned.

  According to the method for producing a non-aqueous electrolyte secondary battery having such a configuration, by using the chromate film layer-formed copper foil whose surface is chromated to the negative electrode current collector, the rust prevention property of the negative electrode current collector is improved. An improved nonaqueous electrolyte secondary battery can be manufactured. Further, in the bonding step, contact resistance can be increased by forming the copper oxide film layer made of copper oxide at least in the negative electrode active material layer non-formed portion as the negative electrode current collector, and as a result It becomes easy to weld the negative electrode terminal and the negative electrode current collector.

  In a preferred embodiment of the method for producing a non-aqueous electrolyte secondary battery disclosed herein, the static friction coefficient of the portion where the negative electrode active material layer is not formed is 0.6 or more (typically 1.0 or less). A copper oxide coating layer is formed so as to be. According to this manufacturing method, by setting the coefficient of static friction of the negative electrode active material layer non-forming portion as described above, the contact resistance of the joint portion between the negative electrode terminal and the negative electrode current collector and a part of the periphery thereof is reduced. As a result, the welding portion and a part of the periphery thereof can be more easily welded.

  In a preferred embodiment of the method for producing a nonaqueous electrolyte secondary battery disclosed herein, the copper oxide coating layer is formed so that the average thickness is 3 nm or more (typically 150 nm or less). It is characterized by that. By forming the copper oxide coating layer having the average thickness, the contact resistance of the junction between the negative electrode terminal and the negative electrode current collector and a part of the periphery thereof can be more suitably increased, and as a result, more suitable. Further, it becomes easy to weld the welded portion and a part of the periphery thereof.

  In a preferred embodiment of the method for producing a nonaqueous electrolyte secondary battery disclosed herein, an organic rust preventive coating layer derived from at least one compound belonging to triazoles is further formed on the copper oxide coating layer. . Thus, by manufacturing the non-aqueous electrolyte secondary battery so as to form the organic anticorrosion coating layer on the copper oxide coating layer, the organic anticorrosion coating layer can be used as the negative electrode current collector. Since it binds to the metal (typically copper) that constitutes it, the rust prevention property of the negative electrode current collector can be improved.

  Further, in a preferred embodiment of the method for producing a nonaqueous electrolyte secondary battery disclosed herein, resistance welding is used as welding between the negative electrode terminal and a part of the negative electrode active material layer non-forming portion. To do. According to this manufacturing method, the oxidation is performed on at least a part of the surface of the negative electrode active material layer non-molded part of the negative electrode current collector on which the chromate film layer is formed and a part of the periphery of the bonded part with the negative electrode terminal. By forming the copper coating layer, the contact resistance between the negative electrode terminal and the negative electrode current collector can be increased. As a result, particularly when resistance welding is performed, the negative electrode terminal and the negative electrode current collector generate sufficient heat even if the input voltage is small, and therefore can be suitably welded.

In addition, according to the present invention, there is provided a vehicle including any one of the nonaqueous electrolyte secondary batteries disclosed herein or the nonaqueous electrolyte secondary battery manufactured by any method as a driving power source.
The above battery maintains high battery performance and is more reliable than conventional batteries (typically when the battery is deformed by impact such as dropping or when the battery is destroyed by piercing a metal object, etc. Resistance) is improved. For this reason, a high-capacity, high-power application (for example, a power source for driving a motor mounted in a vehicle (typically, a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), or an electric vehicle (EV)). (Power supply for driving)).

It is a perspective view which shows typically the external shape of the nonaqueous electrolyte secondary battery which concerns on one Embodiment of this invention. It is a figure which shows typically the cross-sectional structure in the II-II line | wire of the nonaqueous electrolyte secondary battery of FIG. It is a figure which shows the winding electrode body which concerns on one Embodiment of this invention. It is a side view which shows the welding location of the negative electrode active material layer non-formation part of the winding electrode body which concerns on one Embodiment of this invention, and a negative electrode terminal. It is a figure which shows typically the negative electrode active material layer formation part and negative electrode active material layer non-formation part of the negative electrode collector which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the negative electrode active material layer formation part and negative electrode active material layer non-formation part of the negative electrode collector which concerns on one Embodiment of this invention. It is a figure which shows typically resistance welding of the negative electrode collector which concerns on one Embodiment of this invention, and a negative electrode terminal. It is a side view which shows the vehicle (automobile) provided with the nonaqueous electrolyte secondary battery which concerns on one Embodiment of this invention.

In this specification, “non-aqueous electrolyte secondary battery” refers to a battery that can be repeatedly charged, and includes so-called storage batteries such as lithium secondary batteries (typically lithium ion secondary batteries) and nickel metal hydride batteries. . Further, in this specification, the “active material” refers to reversibly occlusion and release (typically insertion) of a chemical species (for example, lithium ion in a lithium ion secondary battery) that serves as a charge carrier in a nonaqueous electrolyte secondary battery. And detachable).

  Hereinafter, preferred embodiments of the nonaqueous electrolyte secondary battery disclosed in the present invention will be described. Matters necessary for implementation other than items specifically mentioned in the present specification can be grasped as design matters of those skilled in the art based on the prior art in this field. The non-aqueous electrolyte secondary battery having such a structure can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field.

  First, a schematic configuration of a nonaqueous electrolyte secondary battery (lithium ion secondary battery) according to an embodiment of the present invention will be described. Although not intended to be particularly limited, as such a lithium ion secondary battery, a flatly wound electrode body (winding electrode body), a nonaqueous electrolyte (electrolyte), and a flat rectangular parallelepiped shape ( A non-aqueous electrolyte secondary battery in a form housed in a (box-type) container is taken as an example, and FIGS. In the following drawings, members / parts having the same action are denoted by the same reference numerals, and redundant description may be omitted or simplified. The dimensional relationship (length, width, thickness, etc.) in each figure does not reflect the actual dimensional relationship.

  FIG. 1 is a perspective view schematically showing an outer shape of a lithium ion secondary battery 100 according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing a cross-sectional structure taken along line II-II of the lithium ion secondary battery shown in FIG.

  As shown in FIGS. 1 and 2, the lithium ion secondary battery 100 according to this embodiment includes a wound electrode body 80 and a hard case (case body) 50. FIG. 3 is a view showing the wound electrode body 80.

  As shown in FIG. 3, the wound electrode body 80 includes a positive electrode sheet 10, a negative electrode sheet 20, and separators 40A and 40B. The positive electrode sheet 10, the negative electrode sheet 20, and the separators 40A and 40B are respectively strip-shaped sheet materials.

  The positive electrode sheet 10 includes a strip-shaped positive electrode current collector 12 and a positive electrode active material layer 14. As the positive electrode current collector 12, a metal foil suitable for the positive electrode is preferably used. For example, a strip-shaped aluminum foil having a predetermined width and a thickness of approximately 15 μm can be used. Moreover, it has the uncoated part 13 along the edge part of the width direction one side of the positive electrode collector 12. FIG. The positive electrode active material layer 14 is held on both surfaces of the positive electrode seed electrode 12 except for the uncoated portion 13. The positive electrode active material layer 14 contains a positive electrode active material, and is formed by applying a positive electrode mixture containing the positive electrode active material to the positive electrode current collector 12.

The positive electrode active material layer 14 includes positive electrode active material particles, a conductive material, and a binder. As the positive electrode active material particles, a material that can be used as a positive electrode active material of a lithium ion secondary battery can be used. For example, a lithium nickel cobalt manganese composite oxide having a layered crystal structure having Li, Ni, Co, and Mn as constituent metal elements can be given. Further, (lithium nickel oxide) LiNiO _2, LiCoO ₂ (lithium cobaltate), LiMn ₂ O ₄ (lithium manganate), include lithium transition metal oxides such as LiFePO ₄ (lithium iron phosphate). Here, LiMn ₂ O ₄ has, for example, a spinel crystal structure. LiNiO ₂ or LiCoO ₂ has a layered rock salt structure. LiFePO ₄ has, for example, an olivine structure. LiFePO ₄ having an olivine structure includes, for example, nanometer order particles. Moreover, LiFePO _{4 having} an olivine structure can be further covered with a carbon film.

  Examples of the conductive material include carbon materials such as carbon powder and carbon fiber. And the said electrically conductive material may be used individually by 1 type selected from such an electrically conductive material, and may use 2 or more types together. As the carbon powder, various carbon blacks (for example, acetylene black, oil furnace black, graphitized carbon black, carbon black, graphite, ketjen black), graphite powder, and the like can be used.

  Further, the binder serves to bind the positive electrode active material particles contained in the positive electrode active material layer 14 and the particles of the conductive material, or bind these particles and the positive electrode current collector 12. Bear. As such a binder, a polymer that can be dissolved or dispersed in a solvent to be used can be used. For example, in a positive electrode mixture composition using an aqueous solvent, a cellulose polymer (carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), etc.), a fluorine resin (for example, 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 can be preferably used. Moreover, in the positive electrode mixture composition using a non-aqueous solvent, polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), etc. can be preferably employed.

  The positive electrode active material layer 14 is prepared, for example, by preparing a positive electrode mixture in which the above-described positive electrode active material particles and a conductive material are mixed in a paste (slurry) with a solvent, and the positive electrode mixture is applied to the positive electrode current collector 12. , Dried and rolled. At this time, any of an aqueous solvent and a non-aqueous solvent can be used as the solvent for the positive electrode mixture. A suitable example of the non-aqueous solvent is 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 about 50 wt% or more (typically 50 to 95 wt%), and usually about 70 to 95 wt% (for example, 75 to 90 wt%). It is more preferable. Moreover, the ratio of the electrically conductive material to the whole positive electrode mixture can be, for example, about 2 to 20 wt%, and is usually preferably about 2 to 15 wt%. In the composition using the binder, the ratio of the binder to the whole positive electrode mixture can be, for example, approximately 1 to 10 wt%, and is preferably approximately 2 to 5 wt%.

  As shown in FIG. 3, the negative electrode sheet 20 includes a strip-shaped negative electrode current collector 22 and a negative electrode active material layer (negative electrode active material layer forming portion) 24. For the negative electrode current collector 22, a metal foil suitable for the negative electrode is preferably used. For example, a strip-shaped copper foil having a predetermined width and a thickness of about 10 μm can be used. In addition, on one side in the width direction of the negative electrode current collector 22, an uncoated portion (negative electrode active material layer non-forming portion) 23 is provided along the edge portion. The negative electrode active material layer 24 is held on both surfaces of the negative electrode current collector 22 except for the uncoated portion 23. The negative electrode active material layer 24 contains a negative electrode active material, and is formed by applying a negative electrode mixture containing the negative electrode active material to the negative electrode current collector 22.

  The negative electrode active material layer 24 includes negative electrode active material particles, a thickener, a binder, and the like. As said negative electrode active material particle, the material of 1 type, or 2 or more types conventionally used for a lithium ion secondary battery as a negative electrode active material can be used without limitation. For example, a particulate carbon material (carbon particles) including a graphite structure (layered structure) at least in part. More specifically, the negative electrode active material is, for example, natural graphite, natural graphite coated with an amorphous carbon material, graphite (graphite), non-graphitizable carbon (hard carbon), graphitizable carbon ( Soft carbon) or a carbon material combining these may be used.

  Moreover, the polymer material illustrated as a binder of the positive electrode active material layer 14 can be used for the said binder. For example, the binder is composed of at least one of an aqueous polymer containing rubbers and a non-aqueous polymer. Examples of the water-based polymer containing rubbers include styrene butadiene rubber (SBR). Here, the styrene-butadiene rubber is a copolymer containing styrene and 1,3-butadiene, and the copolymerization mode is not particularly limited. Further, it may be a modified SBR obtained by copolymerizing an unsaturated carboxylic acid or an unsaturated nitrile compound. Other examples of the polymer that is dispersed or dissolved in water include polyacrylate (acrylic acid ester homopolymer or copolymer), polyurethane, and the like. One of these polymers may be used alone, or two or more thereof may be used in combination.

  The negative electrode active material layer 24 is prepared, for example, by preparing a negative electrode mixture in which the above-described negative electrode active material particles and a binder are mixed in a paste (slurry) with a solvent, applied to the negative electrode current collector 22, and dried. It is formed by rolling. At this time, any of an aqueous solvent and a non-aqueous solvent can be used as the solvent for the negative electrode mixture. A suitable example of the non-aqueous solvent is N-methyl-2-pyrrolidone (NMP). The polymer material described above 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.

  Separator 40A, 40B is a member which separates the positive electrode sheet 10 and the negative electrode sheet 20, as shown in FIG. 2 or FIG. Separator 40A, 40B is comprised with the strip | belt-shaped sheet | seat material of the predetermined width which has several fine holes. As the separators 40A and 40B, for example, a single layer structure separator or a multilayer structure separator made of a porous polyolefin resin can be used. As shown in FIG. 3, the width b1 of the negative electrode active material layer 24 is slightly wider than the width a1 of the positive electrode active material layer 14. Further, the widths c1 and c2 of the separators 40A and 40B are slightly wider than the width b1 of the negative electrode active material layer 24, that is, c1, c2> b1> a1.

Separator 40A, 40B is constituted by a sheet-like member. The separators 40A and 40B may be members that insulate the positive electrode active material layer 14 and the negative electrode active material layer 24 and allow the electrolyte to move. Therefore, the separator 40A, 40B is not limited to a sheet-like member, for example, the separators 40A and 40B are layers of insulating particles formed on the surface of the positive electrode active material layer 14 or the negative electrode active material layer 24 instead of the sheet-like member. You may comprise. Here, as the particles having insulating properties, inorganic fillers having insulating properties (for example, fillers such as metal oxides and metal hydroxides) or resin particles having insulating properties (for example, particles such as polyethylene and polypropylene) ).

  In the wound electrode body 80 having such a configuration, the positive electrode sheet 10 and the negative electrode sheet 20 are stacked so that the positive electrode active material layer 14 and the negative electrode active material layer 24 face each other with the separators 40A and 40B interposed therebetween. ing. More specifically, in the wound electrode body 80, the positive electrode sheet 10, the negative electrode sheet 20, and the separators 40A, 40B are stacked in the order of the positive electrode sheet 10, the separator 40B, the negative electrode sheet 20, and the separator 40A.

  Further, the positive electrode active material layer 14 and the negative electrode active material layer 24 face each other with the separators 40A and 40B interposed therebetween. Then, on one side of the portion where the positive electrode active material layer 14 and the negative electrode active material layer 24 face each other, a portion of the positive electrode current collector 12 where the positive electrode active material layer 14 is not formed (uncoated portion 13) protrudes. Yes. On the side opposite to the side where the uncoated portion 13 protrudes, a negative electrode active material layer non-forming portion 23 in which the negative electrode active material layer 24 is not formed of the negative electrode current collector 22 protrudes. Moreover, the positive electrode sheet 10, the negative electrode sheet 20, and the separators 40A and 40B are wound along the winding axis WL set in the width direction of the positive electrode sheet 10 in a state where they are overlapped in this way.

  As shown in FIG. 1, the battery case 50 is a so-called rectangular battery case, and includes a container body 52 and a lid body 54. The container body 52 is a flat box-shaped container having a bottomed rectangular tube shape and having one side surface (upper surface) opened. The lid 54 is a member that is attached to the opening (opening on the upper surface) of the container body 52 and closes the opening.

  In a non-aqueous electrolyte secondary battery for in-vehicle use, it is desired to improve weight energy efficiency (battery capacity per unit weight) in order to improve vehicle fuel efficiency. In this embodiment, the container main body 52 and the lid 54 constituting the battery case 50 are made of a light metal such as aluminum or aluminum alloy. Thereby, the weight energy efficiency can be improved.

  The battery case 50 has a flat rectangular internal space as a space for accommodating the wound electrode body 80. Further, as shown in FIG. 1, the flat internal space of the battery case 50 is slightly wider than the wound electrode body 80. A positive terminal 70 and a negative terminal 72 are attached to the lid 54 of the battery case 50. The positive electrode terminal 70 and the negative electrode terminal 72 pass through the battery case 50 (the lid body 54) and come out of the battery case 50. The lid 54 is provided with a safety valve 55 and a liquid injection hole 56.

  As shown in FIG. 3, the wound electrode body 80 is flatly pushed and bent in one direction orthogonal to the winding axis WL. The uncoated portion 13 of the positive electrode current collector 12 and the uncoated portion 23 of the negative electrode current collector 22 are spirally exposed on both sides of the separators 40A and 40B, respectively. As shown in FIG. 4, in this embodiment, the intermediate portions 15 and 25 of the uncoated portions 13 and 23 are gathered together and welded to the welded portion 71 of the positive electrode terminal 70 and the welded portion 73 of the negative electrode terminal 72. Yes. During the welding, due to the difference in the materials, for example, ultrasonic welding is used for welding the positive electrode terminal 70 (welded portion 71) and the positive electrode current collector 12. Further, for example, resistance welding is used for welding the negative electrode terminal 72 (welded portion 73) and the negative electrode current collector 22. Here, FIG. 4 is a side view showing a welding location between the intermediate portion 25 (15) of the uncoated portion 23 (13) and the electrode terminal 72 (70) in the wound electrode body 80, and is IV in FIG. It is -IV sectional drawing.

  The wound electrode body 80 is attached to the positive terminal 70 and the negative terminal 72 fixed to the lid 54 in a state where the wound electrode body 80 is flatly bent. The wound electrode body 80 is accommodated in a flat internal space of the container body 52 as shown in FIG. The container body 52 is closed by the lid body 54 after the wound electrode body 80 is accommodated. The joint between the lid 54 and the container body 52 is welded and sealed, for example, by laser welding. Thus, the wound electrode body 80 is positioned in the battery case 50 by the electrode terminals 70 and 72 fixed to the lid body 54 (battery case 50).

Thereafter, an electrolytic solution is injected into the battery case 50 from a liquid injection hole 56 provided in the lid 54. As the electrolytic solution, a so-called non-aqueous electrolytic solution that does not use water as a solvent is used. In this example, an electrolytic solution in which LiPF ₆ is contained at a concentration of about 1 mol / liter in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a mixed solvent having a volume ratio of about 1: 1) is used. Yes. Thereafter, a metal sealing cap is attached to the liquid injection hole 56 (for example, by welding) to seal the battery case 50. The electrolytic solution is not limited to the electrolytic solution exemplified here. For example, non-aqueous electrolytes conventionally used for lithium ion secondary batteries can be used as appropriate.

  Next, the negative electrode current collector 22 according to the present invention will be described in detail together with the manufacturing method. A method for producing a non-aqueous electrolyte secondary battery (here, a lithium ion secondary battery) according to the present invention includes a non-aqueous electrolyte secondary battery in which an electrode body including a positive electrode and a negative electrode and an electrolyte are accommodated in a battery case. This is a method for manufacturing a secondary battery. And a preparation step of preparing a negative electrode current collector having a negative electrode active material layer forming portion including a negative electrode active material layer, a negative electrode active material layer non-forming portion not including the negative electrode active material layer, and a negative electrode terminal; A bonding step of bonding the negative electrode terminal to a part of the negative electrode active material layer non-forming portion. 5A and 5B are schematic views showing the negative electrode current collector 22 of the lithium ion secondary battery 100 according to the present invention. As shown in FIG. 5A, the negative electrode current collector 22 includes a negative electrode active material layer forming part 24 in which a negative electrode active material layer containing a negative electrode active material is formed, and a negative electrode active material layer in which a negative electrode active material layer is not formed. And a forming part (uncoated part) 23. The negative electrode current collector 22 is electrically connected to the negative electrode terminal 72, and the negative electrode terminal 72 is joined to a part of the negative electrode active material layer non-forming portion 23 of the negative electrode current collector 22.

  As described above, a strip-shaped copper foil is used for the negative electrode current collector 22 prepared in the preparation step, and the chromate-treated chromate film layer 27 is formed on the surface of the copper foil. In other words, the negative electrode current collector 22 uses a chromate film layer-formed copper foil whose surface is chromated. Thus, by forming the chromate film layer 27 on the surface of the negative electrode current collector 22, the antirust property of the negative electrode current collector 22 can be improved. Moreover, the negative electrode terminal prepared by the said preparation process is good in it being a negative electrode terminal which consists of copper.

The chromate film layer 27 may be a known one, and for example, chromic acid, sodium dichromate, potassium dichromate, etc. can be used as a material. Typically, the chromium precipitation after the formation of the chromate film layer is a state in which Cr (OH) ₃ and Cr ₂ O ₃ are mixed, and hexavalent chromium that adversely affects the human body is not contained. It is deposited in the form of chromium. The chromic acid solution may be either alkaline or acidic. Although the present invention is not particularly limited, the average thickness of the chromate film layer 27 may be 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. In addition, the formation method of the chromate film layer 27 does not particularly characterize the present invention, and a conventional method can be used.

  However, the chromate film layer-formed copper foil is subjected to a chromate treatment, so that the surface of the negative electrode current collector 22 is mixed with chromium oxide, and current flows easily because the conductivity of chromium oxide is good. . Therefore, the negative electrode current collector 22 has good conductivity and low contact resistance. Therefore, as shown in FIG. 5B, the nonaqueous electrolyte secondary battery according to the present invention has a further surface of the chromate film layer 27 applied to the surface of the negative electrode active material layer non-formation portion 23 in the negative electrode current collector 22, that is, Then, a copper oxide coating layer 28 made of copper oxide is formed by a surface treatment method to be described later at a part where the negative electrode terminal 72 is joined and a part of its periphery. However, the copper oxide coating layer 28 may be formed at least on the surface of the chromate coating layer 27 on the negative electrode active material layer non-formation portion 23 of the negative electrode current collector 22, and the negative electrode active material layer of the negative electrode current collector 22 may be used. A copper oxide coating layer 28 may be formed on the surface of the chromate coating layer 27 on the forming portion 24, or the copper oxide coating layer 28 may not be formed. Note that the chromate film layer 27 is typically lost during resistance welding between a negative electrode terminal 72 and a negative electrode active material layer non-forming portion 23 described later. Therefore, in FIG. 5B, the chromate film layer 27, which is the upper layer of the negative electrode active material layer non-forming portion 23, is omitted.

  Moreover, the static friction coefficient of the negative electrode active material layer non-formation part 23 is 0.6 or more (typically 1.0 or less), preferably 0.7 or more, more preferably 0.8 or more. If the static friction coefficient of the negative electrode active material layer non-formation part 23 is too smaller than 0.6, the surface of the negative electrode active material layer non-formation part 23 may be smooth, and welding with the negative electrode terminal 72 may be difficult. is there. Therefore, by making the static friction coefficient of the negative electrode active material layer non-forming portion 23 within the above range, the contact resistance of the junction between the negative electrode terminal 72 and the negative electrode current collector 22 and a part of the periphery thereof can be more suitably increased. As a result, it becomes easier to weld the welded portion and a part of the periphery thereof more suitably.

  The average thickness of the copper oxide coating layer 28 is 3 nm or more (typically 150 nm or less), preferably 5 nm or more, and more preferably 10 nm or more. When the average thickness of the copper oxide coating layer 28 is formed to be thinner than the above range, the conductivity becomes high, so that resistance heating during welding cannot be expected, and there is a possibility that welding cannot be suitably performed. Therefore, by forming the copper oxide film layer 28 having an average thickness within the above range, the contact resistance between the negative electrode terminal 72 and the negative electrode current collector 22 and part of the periphery thereof can be increased more suitably. As a result, it becomes easier to weld the welded portion and a part of the periphery thereof more suitably. In addition, the measuring method of the average thickness of the copper oxide film layer 28 is X-ray photoelectron spectroscopy (XPS).

  The method of forming the copper oxide film layer 28 on the surface of the negative electrode active material layer non-forming part 23 is not particularly limited to the present invention, and a generally used surface treatment method can be used. As an example, there is a treatment method in which physical energy such as plasma irradiation or ultraviolet (UV) irradiation by corona discharge is applied to the surface. For example, using a commercially available general corona surface treatment apparatus (high-frequency power supply apparatus), a low-temperature plasma irradiation is performed on a joint portion of the negative electrode active material layer non-forming portion 23 with the negative electrode terminal 72 and a part of the periphery thereof ( For example, foil conveyance speed: 10 to 20 m / min, applied voltage: 5 to 20 kV) can be performed. Specifically, a dielectric (insulator) is disposed between a pair of metal electrodes provided in a corona surface treatment apparatus (high-frequency power supply apparatus), and a high-frequency high voltage is applied to the electrodes to thereby reduce the temperature between the electrodes. Plasma (non-equilibrium plasma) is generated, and the surface of the current collector (metal stay) transported between the electrodes can be treated. By performing such surface treatment, it is possible to form the copper oxide film layer 28 at a part where the negative electrode active material layer non-forming part 23 is bonded to the negative electrode terminal 72 and a part of the periphery thereof. As a result, the contact resistance of the negative electrode active material layer non-forming portion 23 with the negative electrode terminal 72 and a part of the periphery thereof can be increased, and the negative electrode terminal 72 and the negative electrode current collector 22 can be easily welded. .

  Further, as shown in FIG. 5B, an organic rust preventive coating layer 29 may be formed on the copper oxide coating layer 28 of the negative electrode active material layer non-forming portion 23. The organic antirust coating layer 29 is made of at least one compound belonging to triazoles. Since the compounds belonging to the triazoles can form a film by bonding with copper, the organic rust preventive film layer 29 is uniformly formed on the joint portion 26 with the negative electrode terminal 72 and a part of the periphery thereof. Can do. Further, since compounds belonging to triazoles do not contain Si element, the negative electrode 20 becomes brittle when alloyed with the metal constituting the negative electrode current collector 22 such as the above-mentioned silane coupling agent containing Si element. Further, it is possible to prevent a decrease in welding strength and a decrease in adhesion between the negative electrode active material and the negative electrode current collector 22. Moreover, the organic rust preventive coating layer 29 is also excellent in rust prevention.

  The following compounds can be used as triazoles that form the organic rust preventive coating layer 29. For example, benzotriazoles such as benzotriazole (BTA) and tolyltriazole (TTA), imidazoles such as 2-undecylimidazole and 2-heptadecylimidazole, mercaptobenzothiazole and salts thereof, and mercaptans such as ethyl mercaptan are used. be able to. Among these, in particular, benzotriazole or tolyltriazole belonging to benzotriazoles can prevent the above-described improvement in rust prevention, decrease in welding strength, and decrease in adhesion between the negative electrode active material and the negative electrode current collector 22. Therefore, it can be particularly preferably used.

Although the present invention is not particularly limited, the average thickness of the organic anticorrosive coating layer 29 is 0.5 nm or more and 3.0 nm or less, preferably 0.5 nm or more and 2.0 nm or less. The measuring method of the average thickness of the organic rust preventive coating layer 29 is X-ray photoelectron spectroscopy (XPS). Necessary when the average thickness of the organic anticorrosive coating layer 29 is too thin than the above range, because the contact resistance value between the negative electrode current collector 22 and the negative electrode terminal 72 is low and heat generation due to sufficient resistance cannot be expected. The above input voltage is required. As a result, the melted portion (joint portion 73 and a part of the periphery thereof) is likely to be scattered, which may cause a voltage drop failure. On the other hand, when the average thickness of the organic rust preventive coating layer 29 is too thick than the above range, the function of the negative electrode current collector 22 may not be sufficiently exhibited. Therefore, by setting the average thickness of the organic rust preventive coating layer 29 within the above-described range, a melted portion (one part of the joint portion and its periphery) between the negative electrode active material layer non-formed portion 23 and the negative electrode terminal 72 due to excessive resistance heat generation. Part) does not scatter, and thus the lithium ion secondary battery 100 can be manufactured in which the rust prevention property is improved more suitably and the welding strength is prevented from being lowered. In addition, when the average thickness of the organic rust preventive coating layer 29 is within the above range, it is preferable to form the organic rust preventive coating layer 29 on both the negative electrode current collector 22 and the negative electrode terminal 72. The coating layer 29 may be formed on either the negative electrode current collector 22 or the negative electrode terminal 72. In the preparation step in the method for manufacturing a secondary battery according to the present invention, the negative electrode current collector 22 and the negative electrode terminal 72 having the above-described configuration are prepared.

  And in the welding process in the manufacturing method of the nonaqueous electrolyte secondary battery which concerns on this invention, the negative electrode terminal 72 is welded to the part in which the copper oxide film layer 28 of the surface of the negative electrode active material layer non-formation part 23 was formed. In this welding, resistance welding may be used as described above. As shown in FIG. 4, in the manufacturing method according to the present invention, the intermediate portion 25 of the uncoated portion (negative electrode active material layer non-forming portion) 23 is gathered and welded to the welded portion 73 of the negative electrode terminal 72. FIG. 6 is a view schematically showing the state of resistance welding of the negative electrode current collector 22 and the negative electrode terminal 72. As shown in FIG. 6, the welded portion 26 of the negative electrode active material layer non-forming portion 23 is shown. That is, the lower electrode 120 is attached to the welded portion with the negative electrode terminal 72 where the copper oxide coating layer 28 is formed, and the upper electrode 110 is attached to the welded portion of the negative electrode terminal 72. The upper electrode 110 is pressed against the lower electrode 120 side, and the lower electrode 120 is pressed against the upper electrode 110 side, whereby the welded portion 26 and the negative electrode of the negative electrode active material layer non-formation portion 23 in the negative electrode current collector 22 Resistance welding is performed so that the welded portion of the terminal 72 is in contact.

In resistance welding, welding is performed using resistance heat generated by passing an electric current through the material to be welded. When only the chromate film layer 27 is formed, the surface of the negative electrode active material non-formation portion 23 of the negative electrode current collector 22 is mixed with chromium oxide, and the chromium oxide is conductive. Current flows more easily than the negative electrode current collector 22 in which no is formed. The negative electrode terminal 72 is usually subjected to barrel polishing or degreasing treatment to remove foreign matter, and the surface thereof is smooth. Therefore, when the negative electrode terminal 72 and the negative electrode current collector 22 are resistance-welded, the contact area between the negative electrode terminal 72 and the negative electrode current collector 22 is increased, so that the contact resistance is lowered and resistance heating cannot be expected.

  However, in the nonaqueous electrolyte secondary battery 100 having the configuration shown in FIGS. 5A and 5B, at least the negative electrode of the surface of the negative electrode active material layer non-molded portion 23 of the negative electrode current collector 22 on which the chromate film layer 27 is formed. The contact resistance between the negative electrode terminal 72 and the negative electrode current collector 22 can be increased by forming the copper oxide coating layer 28 at the junction with the terminal 72 and a part of the periphery thereof. As a result, at the time of welding by resistance welding (typically, the chromate film layer 27 is lost at the time of resistance welding), the negative electrode terminal 72 and the negative electrode current collector 22 generate sufficient heat even when the input voltage is small. Therefore, it can weld suitably. As described above, the nonaqueous electrolyte secondary battery 100 having the configuration according to the present invention can be manufactured.

  The non-aqueous electrolyte secondary battery disclosed herein can be used for various applications, but maintains high battery performance and is more reliable than the conventional one (typically, the battery is deformed by impact such as dropping). And the resistance when the battery is destroyed by piercing a metal object or the like is improved. Therefore, for example, the non-aqueous electrolyte secondary battery 100 disclosed herein can be suitably used as a power source (drive power source) for a motor mounted on a vehicle 1 such as an automobile as shown in FIG. Although the kind of vehicle 1 is not specifically limited, Typically, a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), and an electric vehicle (EV) are mentioned. Moreover, the nonaqueous electrolyte secondary battery 100 may be used alone, or may be used in the form of an assembled battery formed by connecting a plurality of the batteries in series and / or in parallel.

  Hereinafter, some specific examples will be described, but the present invention is not intended to be limited to the specific examples.

A nonaqueous electrolyte secondary battery provided with a wound electrode body was produced by the following procedure.
<Example 1>
[Positive electrode sheet]
First, a positive electrode current collector using a strip-shaped aluminum foil having a thickness of 15 μm and a positive electrode active material layer coated on a portion excluding one end (uncoated portion) of the positive electrode current collector A prepared positive electrode sheet was prepared.

[Negative electrode sheet]
A negative electrode current collector in which a chromate coating layer having an average thickness of 2 nm using a chromium-based trivalent chromium complex is applied to the surface of a strip-shaped electrolytic copper foil having a thickness of 10 μm, and one of the negative electrode current collector A negative electrode sheet provided with a negative electrode active material layer coated on a portion excluding an end portion (uncoated portion) was prepared. Next, a copper oxide coating layer is formed by performing plasma irradiation by a corona discharge method using a high frequency power source on an uncoated portion of the negative electrode current collector of the negative electrode sheet, that is, a negative electrode active material layer non-forming portion. A negative electrode sheet for a non-aqueous electrolyte secondary battery according to Example 1 was prepared. For the plasma irradiation by the corona discharge method, a special high frequency power source CT series: CT-0212 manufactured by Kasuga Electric Co., Ltd. is used, and the electrolytic copper foil transported between the electrodes connected to the high frequency power source is transported. The speed is 15 m / min, the applied voltage is 14 kV, and the power at this time is 0.5 kW.

[Winded electrode body]
The positive electrode sheet and the negative electrode sheet are stacked via the separator sheet so that the battery capacity is 3.6 Ah, the uncoated portion of the positive electrode sheet protrudes from one end of the separator sheet, and the other of the separator sheet The wound electrode body according to Example 1 is manufactured by winding so that the uncoated part (negative electrode active material layer non-formed part) of the negative electrode sheet protrudes from the end (opposite side of the uncoated part of the positive electrode sheet). did.

[Positive and negative terminals]
Next, a positive electrode terminal made of aluminum having a thickness of 1.5 mm and a negative electrode terminal made of a cylinder having a thickness of 1 mm were prepared. And the welding part with the winding electrode body was bend | folded so that the positive electrode terminal and the negative electrode terminal might be along the uncoated part collected near the center part of the winding electrode body. Thereafter, the welded portion of the positive electrode terminal was pressed so as to have a thickness of 1 mm, and the welded portion of the negative electrode terminal was pressed so as to have a thickness of 0.6 mm. Then, the positive electrode terminal and the negative electrode terminal were subjected to barrel polishing and degreasing treatment to remove foreign matters, and the positive electrode terminal and the negative electrode terminal according to Example 1 were produced.

[Nonaqueous electrolyte secondary battery]
Using the wound electrode body (positive electrode sheet, negative electrode sheet), positive electrode terminal, and negative electrode terminal prepared by the above-described procedure, a nonaqueous electrolyte secondary battery was prepared by the following procedure.
(1) The negative electrode active material layer non-formed part (uncoated part) of the negative electrode sheet (negative electrode current collector) is gathered together and the welded part of the negative electrode terminal is brought into contact with each other to be resistance welded under the following welding power source and welding conditions. Did.
Welding power source: Resistance Welder Nag System Co., Ltd., DDC Welder DNWS-5500-4M
Welding conditions: input voltage 8V, time 6ms, pressurization 1.5kN
(2) The uncoated portions of the positive electrode sheet (positive electrode current collector) were gathered together and ultrasonically welded under the following welding power source and welding conditions so as to contact the welded portion of the positive electrode terminal.
Welding power source: Nippon Emerson Co., Ltd., 2000Xdt20: 2.5 power supply (2500W)
Welding conditions: Energy 500J, trigger pressure 800N, amplitude 50%
(3) The positive electrode terminal and negative electrode terminal welded to the wound electrode body were inserted into the container body (metal case), and the lid body and the container body were laser-welded and sealed.
(4) The nonaqueous electrolyte was injected from the injection hole of the lid, and then sealed.
As described above, the nonaqueous electrolyte secondary battery according to Example 1 was produced.

<Example 2>
Except that the power when the copper oxide film layer was formed by performing plasma irradiation by a corona discharge method using a high frequency power source in the negative electrode active material layer non-forming portion was 0.3 kW, the same as in Example 1 A nonaqueous electrolyte secondary battery according to Example 2 was produced.

<Comparative Example 1>
Do not form a copper oxide coating layer on the surface of the negative electrode current collector non-formation portion of the negative electrode current collector of the negative electrode sheet, and the input voltage at the time of resistance welding between the negative electrode current collector and the negative electrode terminal is 15 V A nonaqueous electrolyte secondary battery according to Comparative Example 1 was produced in the same manner as in Example 1 except that.

[Contact resistance between negative electrode current collector and negative electrode terminal]
In the nonaqueous electrolyte secondary batteries according to Examples 1 and 2 and Comparative Example 1, the contact resistance value between each negative electrode current collector and the negative electrode terminal was measured. First, a wound electrode body wound in 60 layers with a width of 30 mm and a negative electrode terminal are sandwiched between two resistance welding electrodes having a tip area of 4 mm. And the contact resistance value when it pressurized with 1000N with respect to the winding electrode body and the negative electrode terminal was measured. The results are shown in Table 1.

[Static friction coefficient]
In the nonaqueous electrolyte secondary batteries according to Examples 1 and 2 and Comparative Example 1, the static friction coefficient between the respective negative electrode current collectors was measured. As the measurement method, first, a square weight of SUS306 having a weight of 259 g and an area of a surface in contact with the negative electrode current collector of 11.1 cm ² was prepared, and the upper surface where two negative electrode current collectors were stacked. The weight was placed on Then, the weight is slid in the horizontal direction at a sliding speed of 20 mm / min, and the frictional force moving between the negative electrode current collectors at that time is measured, and the static friction coefficient (static friction coefficient = maximum load / weight weight) is measured from the measurement result. ) The results are shown in Table 1.

[Average thickness of copper oxide coating layer]
Using X-ray photoelectron spectroscopy (XPS), a copper foil in which a copper oxide film layer and a negative electrode current collector (negative electrode active material layer non-forming portion) are formed at a depth at which the maximum value of oxygen atoms is halved; As the boundary, the average thickness of the copper oxide coating layers according to Examples 1 and 2 and Comparative Example 1 was measured. The results are shown in Table 1.

[Welding current value]
In the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Example 1, the welding current value that flowed during resistance welding between each negative electrode current collector and the negative electrode terminal was measured. The results are shown in Table 2.

[Number of spatters]
In the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Example 1, a particle counter was used to count sputters of 50 μm or more scattered outside from the welded portion of each negative electrode current collector and negative electrode terminal. . The results are shown in Table 2.

[Welding strength]
Using a tensile tester, a wound electrode body resistance-welded to the negative electrode terminal was fixed to the tensile tester, and the breaking peak strength when the tip of the negative electrode terminal was grasped and pulled up was measured. This weld strength measurement was performed on Examples 1 and 2 and Comparative Example 1, and the results are shown in Table 2.

[Voltage failure after initial charge / discharge]
In the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Example 1, initial charge / discharge was performed according to the following procedure.
(1) Charging (CC charging) at a constant current of 1/5 C charging rate for 2 hours and resting for 10 minutes.
(2) Discharge at a constant current of up to 3.0 V at a discharge rate of 1/5 C (CC discharge) and pause for 10 minutes.
(3) After charging with a constant current up to 4.1 V (CC charge) at a charge rate of 1/3 C, discharge with a constant voltage (CV discharge) up to 2/100 C and rest for 10 minutes.
(4) After discharging at a constant current of up to 3.0 V (CC discharge) at a discharge rate of 1/3 C, discharging at a constant voltage up to 2/100 C (CV discharging) and resting for 10 minutes.
(5) Charge at a constant current up to 4.1 V at a charge rate of 1/5 (CC charge).
After the initial charging in the above procedure, the battery is left in an environment of 45 ° C. for 24 hours, and the voltage value at that time is set to V1. Then, it was further left for 4 days in an environment of 25 ° C., and the voltage value at that time was set to V2. At this time, a non-aqueous electrolyte secondary battery deviating from (V1−V2) × 3σ was regarded as a voltage failure. The results are shown in Table 2.

  As shown in Table 1 and Table 2, in the nonaqueous electrolyte secondary battery according to Comparative Example 1 in which the copper oxide coating layer is not formed on the negative electrode current collector (negative electrode active material layer non-formation part), the negative electrode current collector and the negative electrode Since the contact resistance between the terminals is as low as 0.47 mΩ, and heat generation due to contact resistance cannot be expected, a large input voltage of about 15 V is required during resistance welding, and rapid heat generation due to overcurrent (30 kA) causes sputtering. The number of occurrences was large and the welded part was likely to be scattered. As a result, it is considered that a voltage drop failure after the initial charge / discharge occurred.

  On the other hand, as shown in Table 1, in the non-aqueous electrolyte secondary battery in which the copper oxide coating layer is formed on the surface of the negative electrode current collector (negative electrode active material layer non-forming part) according to Examples 1 and 2, the above negative electrode current collector is used. The surface of the electric body was covered with OH groups and covered with copper oxide, and the average thickness of the copper oxide coating layer was 3 nm or more. Further, the contact resistance value between the negative electrode current collector and the negative electrode terminal is as high as 1 mΩ or more, and heat generation due to the contact resistance can be expected. As a result, when resistance welding was performed, the negative electrode current collector and the negative electrode terminal sufficiently generated heat even at a small input voltage of about 8 V, and the above-described resistance welding could be easily performed. In addition, since the non-aqueous electrolyte secondary batteries according to Examples 1 and 2 have a static friction coefficient of 0.6 or more on the surface of the negative electrode current collector, a stable contact surface of the negative electrode current collector is obtained. Moreover, the problem that an overcurrent flows and a part of the welded portion melts can be prevented. As a result, in the non-aqueous electrolyte secondary batteries according to Examples 1 and 2, the average thickness of the copper oxide coating layer was set to 3 nm or more (preferably 5 nm or more, more preferably 10 nm or more), and the static friction on the surface of the negative electrode current collector By setting the coefficient to 0.6 or more (preferably 0.7 or more, more preferably 0.8 or more), it has a strong welding strength (average 350 N) with little variation (about 36 N) as shown in Table 2, In addition, it is possible to obtain a non-aqueous electrolyte secondary battery that does not have a poor voltage drop.

1 Automobile (vehicle)
10 Positive electrode sheet (positive electrode)
12 Positive electrode current collector 13 Uncoated part 14 Positive electrode active material layer 15 Intermediate part 20 Negative electrode sheet (negative electrode)
22 Negative electrode current collector 23 Uncoated part (negative electrode active material layer non-formed part)
24 Negative electrode active material layer (negative electrode active material layer forming part)
25 Intermediate part 26 Welded part 27 Chromate film layer 28 Copper oxide film layer 29 Organic anticorrosive film layer 40A, 40B Separator sheet 50 Battery case 52 Container body 54 Lid 55 Safety valve 56 Injection hole 70 Positive electrode terminal 71 Welded part 72 Negative electrode terminal 73 Welded part 80 Winding electrode body 100 Non-aqueous electrolyte secondary battery (lithium ion secondary battery)
110 Upper electrode 120 Lower electrode WL Winding shaft

Claims (12)

An electrode body including a positive electrode and a negative electrode, and a nonaqueous electrolyte are nonaqueous electrolyte secondary batteries housed in a battery case,
The negative electrode includes a negative electrode terminal and a negative electrode current collector electrically connected to the negative electrode terminal,
The negative electrode current collector is composed of a negative electrode active material layer forming part in which a negative electrode active material layer containing a negative electrode active material is formed and a negative electrode active material layer non-forming part in which the negative electrode active material layer is not formed, And, as the negative electrode current collector, a chromate film layer-formed copper foil whose surface is chromated is used,
The negative electrode terminal is joined to a part of the negative electrode active material layer non-forming portion,
A surface of the negative electrode active material layer non-formation portion, and at least a part of the junction with the negative electrode terminal and a part of the periphery thereof is formed with a copper oxide film layer made of copper oxide. Water electrolyte secondary battery.   The nonaqueous electrolyte secondary battery according to claim 1, wherein a static friction coefficient of the negative electrode active material layer non-forming portion is 0.6 or more.   The non-aqueous electrolyte secondary battery according to claim 1, wherein an average thickness of the copper oxide coating layer is 3 nm or more.   The organic rust preventive coating layer derived from at least one kind of compound belonging to triazoles is formed on a further upper layer of the copper oxide coating layer, according to any one of claims 1 to 3. Non-aqueous electrolyte secondary battery.   The non-aqueous electrolyte 2 according to any one of claims 1 to 4, wherein the negative electrode terminal and a part of the negative electrode active material layer non-forming portion are joined by resistance welding. Next battery.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the chromate film layer is present in at least a part of the negative electrode active material layer forming portion. An electrode body provided with a positive electrode and a negative electrode, and an electrolyte, a method for producing a nonaqueous electrolyte secondary battery housed in a battery case,
Preparing a negative electrode current collector having a negative electrode active material layer forming portion including a negative electrode active material layer, a negative electrode active material layer non-forming portion not including the negative electrode active material layer, and a negative electrode terminal;
Bonding the negative electrode terminal to a part of the negative electrode active material layer non-forming portion,
Here, in the bonding step, as the negative electrode current collector, a chromate film layer-formed copper foil that has been subjected to a chromate treatment in advance is used, and at least the portion where the negative electrode active material layer is not formed is preliminarily made of copper oxide. Forming a copper oxide coating layer,
A method for producing a non-aqueous electrolyte secondary battery, comprising welding the negative electrode terminal to a portion where the copper oxide coating layer is formed.   The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 7, wherein the copper oxide coating layer is formed so that a static friction coefficient of a portion where the negative electrode active material layer is not formed is 0.6 or more.   The method for manufacturing a nonaqueous electrolyte secondary battery according to claim 7 or 8, wherein the copper oxide coating layer is formed so that an average thickness thereof is 3 nm or more.   The non-aqueous electrolyte according to any one of claims 7 to 9, wherein an organic rust preventive coating layer derived from at least one compound belonging to triazoles is formed on an upper layer of the copper oxide coating layer. A method for manufacturing a secondary battery.   11. The nonaqueous electrolyte secondary battery according to claim 7, wherein resistance welding is used as welding between the negative electrode terminal and a part of the negative electrode active material layer non-forming portion. Production method.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 6 or the nonaqueous electrolyte secondary battery produced by the production method according to any one of claims 7 to 11 is used for driving. A vehicle equipped as a power source.

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