Active electrode composition with graphite additive

Abstract

An active composition for an electrode of an electrochemical device. The active composition comprises a nickel hydroxide material, a graphite material, and a polymeric binder.

1 . An active electrode composition, comprising: 
 a nickel hydroxide material;    a graphite having a crystallite height Lc of at least 125 nm; and    a polymeric binder.    
   
   
       2 . The active composition of  claim 1 , wherein said active composition is a paste.  
   
   
       3 . The active composition of  claim 1 , wherein said polymeric binder is an elastomeric polymer.  
   
   
       4 . The active composition of  claim 3 , wherein said elastomeric polymer is a material selected from the group consisting of styrene-butadiene, styrene-butadiene block copolymer, styrene-isoprene-styrene block copolymer and styrene-ethylene-butadiene-styrene block copolymer.  
   
   
       5 . The active composition of  claim 1 , wherein said graphite has a crystallite height Lc of at least 175 nm.  
   
   
       6 . The active composition of  claim 1 , wherein said graphite has an interlayer distance c/2 between 0.335 nm and 0.345 nm.  
   
   
       7 . The active composition of  claim 1 , wherein said graphite material has a BET surface area less than 15 square meters per gram.  
   
   
       8 . The active composition of  claim 1 , wherein said active composition comprises at least 10 weight percent of said graphite material.  
   
   
       9 . An electrode for a battery cell, comprising: 
 a nickel hydroxide material;    a graphite having a crystallite size Lc of at least 125 nm; and and    a polymeric binder.    
   
   
       10 . The electrode of  claim 9 , wherein said polymeric binder is an elastomeric polymer.  
   
   
       11 . The electrode of  claim 9 , wherein said active composition is a paste.  
   
   
       12 . The electrode of  claim 10 , wherein said elastomeric polymer comprises a material selected from the group consisting of styrene-butadiene, styrene-butadiene block copolymer, styrene-isoprene-styrene block copolymer and styrene-ethylene-butadiene-styrene block copolymer.  
   
   
       13 . The electrode of  claim 9 , wherein said graphite has a crystallite height Lc is at least 175 nm.  
   
   
       14 . The electrode of  claim 9 , wherein said active composition is affixed to a conductive substrate, said substrate selected from the group consisting expanded metal, perforated metal, screen or foil.  
   
   
       15 . A nickel-metal hydride battery cell, comprising: 
 a positive electrode comprising an active composition comprising a nickel hydroxide material, a graphite material having a crystallite height of at least 125 nm, and a polymeric binder;    a negative electrode comprising a hydrogen storage alloy active material; and    an alkaline electrolyte.    
   
   
       16 . The battery cell of  claim 18 , wherein said polymeric binder is an elastomeric polymer.  
   
   
       17 . The electrochemical device of  claim 18 , wherein said active composition is a paste.  
   
   
       18 . The electrochemical device of  claim 19 , wherein said elastomeric polymer comprises a material selected from the group consisting of styrene-butadiene, styrene-butadiene block copolymer, styrene-isoprene-styrene block copolymer and styrene-ethylene-butadiene-styrene block copolymer. styrene-butadiene.  
   
   
       19 . The electrochemical device of  claim 18 , wherein said graphite has a crystallite height Lc of at least 175 nm.