Nonaqueous electrolyte secondary battery and manufacturing method therefor

Abstract

A nonaqueous electrolyte secondary battery includes: an electrode assembly; a nonaqueous electrolyte; and a battery case. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode active material layer. The negative electrode includes a negative electrode active material layer. The separator is interposed between the positive electrode and the negative electrode. The battery case accommodates the electrode assembly and the nonaqueous electrolyte. Ends of contact faces of the negative electrode active material layer and the separator are at least partially bonded to each other.

What is claimed is: 
     
         1 . A nonaqueous electrolyte secondary battery comprising:
 an electrode assembly including a positive electrode, a negative electrode and a separator, the positive electrode including a positive electrode active material layer, the negative electrode including a negative electrode active material layer, the separator being interposed between the positive electrode and the negative electrode;   a nonaqueous electrolyte; and   a battery case accommodating the electrode assembly and the nonaqueous electrolyte, wherein   ends of contact faces of the negative electrode active material layer and the separator are at least partially bonded to each other.   
     
     
         2 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein
 the electrode assembly is a flat rolled electrode assembly that is formed by stacking the long positive electrode, the long negative electrode and the long separator and then rolling the stacked positive electrode, negative electrode and separator into an oval shape in cross section with a rolling axis set to a width direction perpendicular to a longitudinal direction of the long positive electrode, the long negative electrode and the long separator, and   the negative electrode active material layer and the separator are bonded to each other at a flat portion of an electrode face of the flat rolled electrode assembly in a band-shaped region along each of ends in the width direction.   
     
     
         3 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein
 the entire contact faces of the negative electrode active material layer and the separator are bonded to each other.   
     
     
         4 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein
 the positive electrode active material layer and the separator are not bonded to each other.   
     
     
         5 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein
 a heat-resistant layer including an electrically insulated inorganic filler is provided on a surface of the positive electrode active material layer.   
     
     
         6 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein
 the negative electrode active material layer and the separator are bonded to each other such that a peeling strength becomes larger than or equal to 0.2 N/m and smaller than or equal to 1.2 N/m.   
     
     
         7 . A manufacturing method for a nonaqueous electrolyte secondary battery, comprising:
 constructing a cell by accommodating an electrode assembly in a battery case, the electrode assembly including a positive electrode, a negative electrode and a separator, the positive electrode including a positive electrode active material layer, the negative electrode including a negative electrode active material layer, the separator being interposed between the positive electrode and the negative electrode;   supplying a nonaqueous electrolyte into the battery case; and   at least partially bonding ends of contact faces of the negative electrode active material layer and the separator to each other in advance of supplying the nonaqueous electrolyte.   
     
     
         8 . The manufacturing method according to  claim 7 , wherein
 the negative electrode active material layer includes a negative electrode active material and a binder, and   the negative electrode and the separator are bonded to each other by, at the time of constructing the cell, bringing the negative electrode active material layer of the negative electrode and the separator into contact with each other and then heating while at least partially pressing the ends of the contact faces.   
     
     
         9 . The manufacturing method according to  claim 7 , further comprising:
 drying the cell after constructing the cell, wherein   the negative electrode active material layer includes a negative electrode active material and a binder, and   the negative electrode and the separator are bonded to each other by, in drying the cell, heating while applying a pressure such that the ends of the contact faces of the negative electrode active material layer and the separator in the electrode assembly are at least partially pressed from an outside of the battery case.   
     
     
         10 . The manufacturing method according to  claim 8 , wherein
 the negative electrode and the separator are bonded to each other by applying a pressure higher than or equal to 0.01 MPa and lower than or equal to 1 MPa between the negative electrode active material layer and the separator in a temperature range higher than or equal to a softening point of the binder and lower than or equal to 125° C.   
     
     
         11 . The manufacturing method according to  claim 7 , wherein
 the negative electrode and the separator are bonded to each other such that a peeling strength becomes larger than or equal to 0.2 N/m and smaller than or equal to 1.2 N/m.   
     
     
         12 . The manufacturing method according to  claim 7 , further comprising: applying aging. 
     
     
         13 . The manufacturing method according to  claim 9 , wherein
 the negative electrode and the separator are bonded to each other by applying a pressure higher than or equal to 0.01 MPa and lower than or equal to 1 MPa between the negative electrode active material layer and the separator in a temperature range higher than or equal to a softening point of the binder and lower than or equal to 125° C.