Lithium secondary cell

Abstract

The invention provides a lithium secondary cell including an inner electrode body impregnated with a non-aqueous electrolyte, made up of a positive electrode and a negative electrode each made of at least one metallic foil wound or laminated together and collectors to lead out a current from this inner electrode body. The edges of the metallic foil of the positive electrode and/or the negative electrode and predetermined parts of the positive electrode collector and/or negative electrode collector are joined together to lead out a current from the inner electrode body. The edges of the metallic foil, the edges (joint edges) arranged to be joined to the predetermined parts of the positive electrode collector and/or the negative electrode collector and the predetermined parts of the positive electrode collector and/or the negative electrode collector are joined together. The lithium secondary cell has excellent productivity and space-saving capability.

What is claimed is:  
     
         1 . A lithium secondary cell comprising: 
 an inner electrode body impregnated with a non-aqueous electrolyte, made up of a positive electrode and a negative electrode each made of at least one metallic foil wound or laminated together; and    a positive electrode collector and a negative electrode collector to lead out a current from the inner electrode body,    wherein the edges of said metallic foils of said positive electrode and/or said negative electrode and predetermined parts of said positive electrode collector and/or said negative electrode collector are joined together to lead out a current from said inner electrode body, and    of the edges of said metallic foils, the arranged edges (joint edges) to be joined to said predetermined parts of said positive electrode collector and/or said negative electrode collector and said predetermined parts of said positive electrode collector and/or said negative electrode collector are joined together.    
     
     
         2 . The lithium secondary cell according to  claim 1 , further comprising an electrode cover including internal terminals, external terminals and a cell cover, wherein said positive electrode collector and/or said negative electrode collector are connected to said internal terminals using electrode leads.  
     
     
         3 . The lithium secondary cell according to  claim 1 , wherein said positive electrode collector and/or said negative electrode collector also serve as an electrode cover.  
     
     
         4 . The lithium secondary cell according to  claim 1 , wherein said joint edges of said metallic foil constituting said positive electrode (positive electrode metallic foil) and a joint having a joint surface at the edge that extends from said predetermined part of said positive electrode collector to said joint edges are joined with the narrow end face of said joint edges facing said joint surface.  
     
     
         5 . The lithium secondary cell according to  claim 4 , wherein said positive electrode metallic foil and said positive electrode collector are made of aluminum or an aluminum alloy.  
     
     
         6 . The lithium secondary cell according to  claim 1 , wherein said predetermined part of said positive electrode collector is the edge of said positive electrode collector.  
     
     
         7 . The lithium secondary cell according to  claim 1 , wherein said joint edges of said metallic foil constituting said negative electrode (negative electrode metallic foil) and a joint having a joint surface at the edge that extends from said predetermined part of said negative electrode collector to said joint edges are joined with the side near said joint edges adhered to said joint surface.  
     
     
         8 . The lithium secondary cell according to  claim 7 , wherein said negative electrode metallic foil and said negative electrode collector are made of copper or a copper alloy.  
     
     
         9 . The lithium secondary cell according to  claim 7 , wherein said side is adhered to said joint surface by bending the part near said joint edges.  
     
     
         10 . The lithium secondary cell according to  claim 7 , wherein columnar crystals are formed from said metallic foil toward said negative electrode collector at the joint between said negative electrode metallic foil and said negative electrode collector.  
     
     
         11 . The lithium secondary cell according to  claim 1 , wherein said predetermined part of said negative electrode collector is the edge of said negative electrode collector.  
     
     
         12 . The lithium secondary cell according to  claim 4 , wherein the joint between said joint edges of said positive electrode metallic foil and said predetermined part of said positive electrode collector (positive electrode joint) is formed by irradiating a convex part protruding toward said joint edges formed on said predetermined part of said positive electrode collector with energy beams, melting said convex part of said positive electrode collector and welding said convex part of said positive electrode collector with said joint edges of said positive electrode metallic foil.  
     
     
         13 . The lithium secondary cell according to  claim 7 , wherein the joint between said joint edges of said negative electrode metallic foil and said predetermined part of said negative electrode collector (negative electrode joint) is formed by irradiating a convex part protruding toward said joint edges formed on said predetermined part of said negative electrode collector with energy beams, melting said convex part of said negative electrode collector and welding said convex part of said negative electrode collector with said joint edges of said negative electrode metallic foil.  
     
     
         14 . The lithium secondary cell according to  claim 1 , wherein said positive electrode collector and/or said negative electrode collector is a cross-, Y- or I-figured tabular collector or a circular collector with partial notching.  
     
     
         15 . The lithium secondary cell according to  claim 1 , wherein said positive electrode collector and/or said negative electrode collector is formed of said convex part and other flat part and the difference between the thickness (L 2 ) of said convex part and the thickness (L 1 ) of said flat part is 0.1 mm or more.  
     
     
         16 . The lithium secondary cell according to  claim 15 , wherein the thickness (L 1 ) of said flat part of said positive electrode collector is 0.4 mm or more.  
     
     
         17 . The lithium secondary cell according to  claim 12 , wherein the thickness (L 2 ) of said convex part of said positive electrode collector is 0.6 mm or more.  
     
     
         18 . The lithium secondary cell according to  claim 12 , wherein when said positive electrode joint is formed, said energy beam is irradiated onto said predetermined part at an angle θ (0°<θ<90°) with respect to the normal to the plane including said narrow end face of said positive electrode metallic foil.  
     
     
         19 . The lithium secondary cell according to  claim 12 , wherein when said positive electrode joint is formed, the power density of said energy beam at the irradiation point is 3 kW/mm 2  or more.  
     
     
         20 . The lithium secondary cell according to  claim 15 , wherein the thickness (L 1 ) of said flat part of said negative electrode collector is 0.2 mm or more.  
     
     
         21 . The lithium secondary cell according to  claim 13 , wherein the thickness (L 2 ) of said convex part of said negative electrode collector is 0.4 mm or more.  
     
     
         22 . The lithium secondary cell according to  claim 13 , wherein when said negative electrode joint is formed, said energy beam is irradiated onto said predetermined part at an angle θ (0°≦θ<30°) with respect to the normal to the plane including said side of said negative electrode metallic foil.  
     
     
         23 . The lithium secondary cell according to  claim 13 , wherein when said negative electrode joint is formed, the power density of said energy beam at the irradiation point is 6 kW/mm 2  or more.  
     
     
         24 . The lithium secondary cell according to  claim 15 , wherein when said negative electrode joint is formed, if the thickness of said convex part is L 2  (mm) and said power density is E (kW/mm 2 ), the following Expression (1) is satisfied.  
       [Mathematical Expression 1] 
       L 2 ≦E/7  (1)  
     
     
         25 . The lithium secondary cell according to  claim 13 , wherein irradiation point of said energy beam of said negative electrode collector has a flat shape.  
     
     
         26 . The lithium secondary cell according to  claim 25 , wherein the spot diameter of said irradiation point is 1 mm or less.  
     
     
         27 . The lithium secondary cell according to  claim 12 , wherein said positive electrode collector is placed in such a way that said convex part crosses said narrow end face of said positive electrode metallic foil at quasi-right angles.  
     
     
         28 . The lithium secondary cell according to  claim 12 , wherein said energy beam is irradiated onto said convex part of said positive electrode collector at quasi-right angles with respect to the line crossing said narrow end face of said positive electrode metallic foil at quasi-right angles.  
     
     
         29 . The lithium secondary cell according to  claim 13 , wherein said negative electrode collector is placed in such a way that said convex part crosses said side of said negative electrode metallic foil at quasi-right angles.  
     
     
         30 . The lithium secondary cell according to  claim 13 , wherein said energy beam is irradiated onto said convex part of said negative electrode collector at quasi-right angles with respect to the line crossing said side of said negative electrode metallic foil at quasi-right angles.  
     
     
         31 . The lithium secondary cell according to  claim 12 , wherein said energy beam is not directly irradiated onto said metallic foil.  
     
     
         32 . The lithium secondary cell according to  claim 1 , wherein neighboring metallic foils are placed with a certain gap kept in between.  
     
     
         33 . The lithium secondary cell according to  claim 12 , wherein said energy beam is a laser or electron beam.  
     
     
         34 . The lithium secondary cell according to  claim 33 , wherein said energy beam is a continuous wave.  
     
     
         35 . The lithium secondary cell according to  claim 33 , wherein said laser is a YAG laser.  
     
     
         36 . The lithium secondary cell according to  claim 12 , wherein a joint material for supporting the joint between said positive electrode collector and said positive electrode metallic foil is applied to said positive electrode metallic foil and/or said predetermined part of said positive electrode collector or inserted between said positive electrode metallic foil and said predetermined part of said positive electrode collector and formed by irradiating said predetermined part of said positive electrode collector and said joint material with an energy beam and thereby melting the two and welding said melted predetermined part of said positive electrode collector and said joint material to said joint edges of said positive electrode metallic foil.  
     
     
         37 . The lithium secondary cell according to  claim 13 , wherein a joint material for supporting the joint between said negative electrode collector and said negative electrode metallic foil is applied to said negative electrode metallic foil and/or said predetermined part of said negative electrode collector or inserted between said negative electrode metallic foil and said predetermined part of said negative electrode collector and formed by irradiating said predetermined part of said negative electrode collector and said joint material with an energy beam and thereby melting the two and welding said melted predetermined part of said negative electrode collector and said joint material to said joint edges of said negative electrode metallic foil.  
     
     
         38 . The lithium secondary cell according to  claim 1 , which has a capacity of 2 Ah or more.  
     
     
         39 . The lithium secondary cell according to  claim 1 , which is to be mounted on a vehicle.  
     
     
         40 . The lithium secondary cell according to  claim 39 , which is used for an electric car or hybrid electric car.  
     
     
         41 . The lithium secondary cell according to  claim 39 , which is to be used to start an engine.