Oxidation resistant separator for a battery

Abstract

A lithium ion rechargeable battery comprises: a negative electrode adapted to give up electrons during discharge, a positive electrode adapted to gain electrons during discharge, a microporous separator sandwiched between said positive electrode and said negative electrode, an organic electrolyte being contained within said separator and being in electrochemical communication with said positive electrode and said negative electrode, and an oxidative barrier interposed between said separator and said positive electrode, and thereby preventing oxidation of said separator.

That which is claimed:  
     
         1 . A lithium ion rechargeable battery comprises: 
 a negative electrode adapted to give up electrons during discharge,    a positive electrode adapted to gain electrons during discharge,    a microporous separator sandwiched between said positive electrode and said negative electrode,    an organic electrolyte being contained within said separator and being in electrochemical communication with said positive electrode and said negative electrode, and    an oxidative barrier interposed between said separator and said positive electrode, and thereby preventing oxidation of said separator.    
     
     
         2 . The battery of  claim 1  wherein said separator comprises a polypropylene membrane.  
     
     
         3 . The battery of  claim 1  wherein said separator comprises a polyvinylidene fluoride membrane.  
     
     
         4 . The battery of  claim 1  wherein said separator comprises a multi-layered separator wherein the layer facing the positive electrode being selected from the group consisting of polypropylene, halocarbons, copolymers thereof, and mixtures thereof.  
     
     
         5 . The battery of  claim 1  wherein said oxidative barrier comprises a coating formed on said separator and in contact with said positive electrode.  
     
     
         6 . The battery of  claim 5  wherein said coating comprises a polymer selected from the group consisting of polypropylene, halocarbons, co-polymers thereof, metal oxides, and mixtures thereof.  
     
     
         7 . The battery of  claim 5  wherein said coating comprises an antioxidant.  
     
     
         8 . The battery of  claim 7  wherein said antioxidant being selected from the group consisting of phenols, phosphorus containing compounds, sulfur containing compounds, and mixtures thereof.  
     
     
         9 . The battery of  claim 1  wherein said oxidative barrier comprises a coating formed on said positive electrode and in contact with said separator.  
     
     
         10 . The battery of  claim 9  wherein said coating comprises a polymer selected from the group consisting of polypropylene, halocarbons, co-polymers thereof, metal oxides, and mixtures thereof.  
     
     
         11 . The battery of  claim 9  wherein said coating comprises an antioxidant.  
     
     
         12 . The battery of  claim 11  wherein said antioxidant being selected from the group consisting of phenols, phosphorus containing compounds, sulfur containing compounds, and mixtures thereof.  
     
     
         13 . The battery of  claim 1  wherein said oxidative barrier comprises antioxidants dispersed into the separator.  
     
     
         14 . The battery of  claim 13  wherein said antioxidant being selected from the group consisting of phenols, phosphorus containing compounds, sulfur containing compounds, and mixtures thereof.  
     
     
         15 . The battery of  claim 13  wherein said antioxidant further comprising about 1-10% by weight of said separator.  
     
     
         16 . The battery of  claim 13  wherein said antioxidant being concentrated at the face of said separator adjacent said positive electrode.