Non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector, a positive electrode active material layer on a part of a surface of the positive electrode current collector containing a positive electrode active material, and an insulating layer on other parts of the surface of the positive electrode current collector containing an inorganic filler. The negative electrode includes a negative electrode current collector, and a negative electrode active material layer on a part of a surface of the negative electrode current collector containing a negative electrode active material. The insulating layer includes a first insulating layer disposed along an end portion of the positive electrode active material layer, and a second insulating layer formed at a position separated from the first insulating layer and facing an end portion of the negative electrode active material layer.

What is claimed is: 
     
         1 . A non-aqueous electrolyte secondary battery comprising:
 a positive electrode;   a negative electrode facing the positive electrode; and   a non-aqueous electrolyte, wherein:   the positive electrode includes
 a positive electrode current collector, 
 a positive electrode active material layer which is provided on a part of a surface of the positive electrode current collector and contains a positive electrode active material, and 
 an insulating layer which is provided on other parts of the surface of the positive electrode current collector; 
   the negative electrode includes
 a negative electrode current collector, and 
 a negative electrode active material layer which is provided on a part of a surface of the negative electrode current collector and contains a negative electrode active material; and 
   the insulating layer includes
 a first insulating layer disposed along an end portion of the positive electrode active material layer, and 
 a second insulating layer formed at a position which is separated from the first insulating layer and faces an end portion of the negative electrode active material layer; 
   wherein the first insulating layer and the second insulating layer are separated from each other in a width direction of the positive electrode;   wherein the positive electrode active material layer has, in a sectional view, a flat region where the surface of the positive electrode active material layer is flat and has a substantially uniform thickness, and an end portion region where the surface of the positive electrode active material layer is curved toward the positive electrode current collector at an end portion of the positive electrode active material layer; and   wherein a part of the end portion region is stacked on the first insulating layer.   
     
     
         2 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein an average thickness of the second insulating layer is equal to or greater than a thickness of the negative electrode current collector. 
     
     
         3 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the first insulating layer is formed to be interposed between the positive electrode current collector and the end portion of the positive electrode active material layer and to cover the end portion of the positive electrode active material layer. 
     
     
         4 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein an end portion of the negative electrode on a side facing the second insulating layer is formed by a cut surface. 
     
     
         5 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the positive electrode current collector comprises a non-coated portion between the first insulating layer and the second insulating layer. 
     
     
         6 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the positive electrode layer active material has an end portion the comprises a first inclined surface partly covered by the first insulating layer, and a second inclined surface closer to the positive electrode current collector than the first inclined surface, the second inclined surface being entirely covered with the first insulating layer. 
     
     
         7 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the surface of the positive electrode active material layer is curved such that the thickness of the positive electrode active material layer decreases toward the end portion of the positive electrode active material layer. 
     
     
         8 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the positive electrode active material layer has, in a sectional view, a flat region where the surface of the positive electrode active material layer is flat and has a substantially uniform thickness, and an end portion region where the surface of the positive electrode active material layer is curved such that the thickness of the positive electrode active material layer decreases toward the end portion of the positive electrode active material layer. 
     
     
         9 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the insulating layer comprises an inorganic filler. 
     
     
         10 . A non-aqueous electrolyte secondary battery comprising:
 a positive electrode;   a negative electrode facing the positive electrode; and   a non-aqueous electrolyte, wherein:   the positive electrode includes
 a positive electrode current collector, 
 a positive electrode active material layer which is provided on a part of a surface of the positive electrode current collector and contains a positive electrode active material, and 
 an insulating layer which is provided on other parts of the surface of the positive electrode current collector; 
   and   the insulating layer includes
 a first insulating layer disposed along an end portion of the positive electrode active material layer, and 
 a second insulating layer formed at a position which is separated from the first insulating layer and faces an end portion of the negative electrode active material layer; 
   wherein the first insulating layer and the second insulating layer are separated from each other in a width direction of the positive electrode;   wherein the positive electrode active material layer has, in a sectional view, a flat region where the surface of the positive electrode active material layer is flat and has a substantially uniform thickness, and an end portion region where the surface of the positive electrode active material layer is curved toward the positive electrode current collector at an end portion of the positive electrode active material layer; and   wherein a part of the end portion region is stacked on the first insulating layer.   
     
     
         11 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein an average thickness of the second insulating layer is equal to or greater than a thickness of a current collector of the negative electrode. 
     
     
         12 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein the first insulating layer is formed to be interposed between the positive electrode current collector and the end portion of the positive electrode active material layer and to cover the end portion of the positive electrode active material layer. 
     
     
         13 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein an end portion of the negative electrode on a side facing the second insulating layer is formed by a cut surface. 
     
     
         14 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein the positive electrode current collector comprises a non-coated portion between the first insulating layer and the second insulating layer. 
     
     
         15 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein the positive electrode layer active material has an end portion the comprises a first inclined surface partly covered by the first insulating layer, and a second inclined surface closer to the positive electrode current collector than the first inclined surface, the second inclined surface being entirely covered with the first insulating layer. 
     
     
         16 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein the surface of the positive electrode active material layer is curved such that the thickness of the positive electrode active material layer decreases toward the end portion of the positive electrode active material layer. 
     
     
         17 . The non-aqueous electrolyte secondary battery according to  claim 10 , wherein the positive electrode active material layer has, in a sectional view, a flat region where the surface of the positive electrode active material layer is flat and has a substantially uniform thickness, and an end portion region where the surface of the positive electrode active material layer is curved such that the thickness of the positive electrode active material layer decreases toward the end portion of the positive electrode active material layer. 
     
     
         18 . A method of forming a non-aqueous electrolyte secondary battery comprising the steps of:
 forming a positive electrode;   forming a negative electrode facing the positive electrode; and   forming a non-aqueous electrolyte, wherein:   the positive electrode includes
 a positive electrode current collector, 
 a positive electrode active material layer which is provided on a part of a surface of the positive electrode current collector and contains a positive electrode active material, and 
 an insulating layer which is provided on other parts of the surface of the positive electrode current collector; 
   the negative electrode includes
 a negative electrode current collector, and 
 a negative electrode active material layer which is provided on a part of a surface of the negative electrode current collector and contains a negative electrode active material; and 
   the insulating layer includes
 a first insulating layer disposed along an end portion of the positive electrode active material layer, and 
 a second insulating layer formed at a position which is separated from the first insulating layer and faces an end portion of the negative electrode active material layer; 
   wherein the first insulating layer and the second insulating layer are formed separated from each other in a width direction of the positive electrode;   wherein forming the positive electrode comprises forming the positive electrode active material layer to have, in a sectional view, a flat region where the surface of the positive electrode active material layer is flat and has a substantially uniform thickness, and an end portion region where the surface of the positive electrode active material layer is curved toward the positive electrode current collector at an end portion of the positive electrode active material layer; and   forming a part of the end portion region such that it is stacked on the first insulating layer.   
     
     
         19 . The method of forming a non-aqueous electrolyte secondary battery of  claim 18 , further comprising forming the second insulating layer with an average thickness equal to or greater than a thickness of the negative electrode current collector. 
     
     
         20 . The method of forming a non-aqueous electrolyte secondary battery of  claim 18 , further comprising forming the first insulating layer to be interposed between the positive electrode current collector and the end portion of the positive electrode active material layer and to cover the end portion of the positive electrode active material layer.