Negative electrode, negative active material, method of preparing the negative electrode, and lithium battery including the negative electrode

Abstract

A negative electrode including: a current collector; a negative active material layer formed on the current collector; and a polymer coating layer that is formed on the negative active material layer and comprises a fluorinated acrylate type polymer.

What is claimed is: 
     
         1 . A method of preparing a negative electrode, the method comprising:
 preparing a negative active material composition by mixing a negative active material,a conductive agent, a binder, and a solvent;   forming a negative active material layer by coating a current collector with the negative active material composition; and   forming a polymer coating layer comprising a fluorinated acrylate type polymer on the negative active material layer by coating the negative active material layer with a solution comprising the fluorinated acrylate type monomer and having a viscosity of about 0.5 cP to about 1000 cP and polymerizing the fluorinated acrylate type monomer.   
     
     
         2 . The method of  claim 1 , wherein the fluorinated acrylate type monomer is a monomer represented by Formula 3 below: 
       
         
           
           
               
               
           
         
         wherein: 
         R 3  is a hydrogen atom, a fluorine atom, a C 1  to C 20  alkyl group, a fluorine atom-substituted C 1  to C 20  alkyl group, a C 2  to C 20  alkenyl group, a fluorine atom-substituted C 2 to C 20  alkenyl group, a C 6  to C 20  aryl group, or a fluorine atom-substituted C 6  to C 20  aryl group, R 4  to R 6  are each independently a hydrogen atom, a fluorine atom, CH 3 , CHF 2 , CH 2 F, or CF 3 , 
         X is CH 2 , CHF, or CF 2 , 
         a is an integer of 0 to 10, and b is an integer of 0 to 10, 
         the weight average molecular weight of the fluorinated acrylate type monomer is about 200 to about 500,000, and 
         any one of R 3  to R 6  comprises at least one fluorine atom. 
       
     
     
         3 . The method of  claim 1 , wherein the fluorinated acrylate type monomer further is afluorinated acrylate type monomer represented by Formula 4 below, and the mixed ratio of the monomer represented by Formula 3 to the monomer represented by Formula 4 ranges from about 0.6:0.4 to about 1:0: 
       
         
           
           
               
               
           
         
         wherein: 
         R 7  is H or CH 3 , and R 8  is a linear or branched C 1  to C 9  alkyl group, and the weight average molecular weight of the copolymer obtained by polymerizing the fluorinated acrylate type monomers represented by Formulae 3 and 4 is about 200 to about 500,000. 
       
     
     
         4 . The method of  claim 1 , wherein the fluorinated acrylate type polymer comprises a repeating unit represented by Formula 1: 
       
         
           
           
               
               
           
         
         wherein: 
         R 1  to R 3  are each independently a hydrogen atom, a fluorine atom, a C 1  to C 20  alkyl group, a fluorine atom-substituted C 1  to C 20  alkyl group, a C 2  to C 20  alkenyl group, a fluorine atom-substituted C 2  to C 20  alkenyl group, a C 6  to C 20  aryl group, or a fluorineatom-substituted C 6  to C 20  aryl group, 
         R 4  to R 6  are each independently a hydrogen atom, a fluorine atom, CH 3 , CHF 2 , CH 2 F, or CF 3 , 
         X is CH 2 , CHF, or CF 2 , 
         a is an integer of 0 to 10, and b is an integer of 0 to 10, 
         the weight average molecular weight of the fluorinated acrylate type polymer is in therange of about 200 to about 500,000, and 
         any one of R 1  to R 6  comprises at least one fluorine atom.