Active material for negative electrodes of nonaqueous secondary batteries, and nonaqueous secondary battery

Abstract

An active material having a high capacity for negative electrodes of nonaqueous secondary batteries is provided by pyrolysis of a composite resin (A) which has a silanol group and/or a hydrolysable silyl group and which contains a polysiloxane segment (a1) and a polymer segment (a2) other than the polysiloxane segment (a1), and furthermore, a negative electrode using the above active material and a nonaqueous secondary battery including the above negative electrode are also provided. In addition, by pyrolysis of a dispersion liquid obtained from the composite resin (A), silicon particles, and an organic solvent, an active material having a high capacity for negative electrodes of nonaqueous secondary batteries is provided, and furthermore, a negative electrode using the above active material and a nonaqueous secondary battery including the above negative electrode are also provided.

1 . An active material for negative electrodes of nonaqueous secondary batteries obtained by pyrolysis of a composite resin (A) which has a silanol group and/or a hydrolysable silyl group and which contains a polysiloxane segment (a1) and a polymer segment (a2) other than the polysiloxane segment (a1). 
     
     
         2 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 , wherein the polysiloxane segment (a1) is a polysiloxane segment having a structural unit represented by the following general formula (S-2) and/or the following general formula (S-3) 
       
         
           
           
               
               
           
         
         (in the general formulas (S-2) and (S-3), R 3 , R 4 , and R 5  each independently represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an aryl group, or an aralkyl group having 7 to 12 carbon atoms). 
       
     
     
         3 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 , wherein the content of the polysiloxane segment (a1) is 10 to 95 percent by mass with respect to the composite resin (A). 
     
     
         4 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 , wherein the polymer segment (a2) is a vinyl polymer segment. 
     
     
         5 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 , wherein the composite resin (A) is a composite resin in which the polysiloxane segment (a1) and the polymer segment (a2) are linked to each other by a structure represented by the following structural formula (S-5) 
       
         
           
           
               
               
           
         
         (in the formula, the carbon atom is a carbon atom forming the polymer segment (a2), and the two silicon atoms are silicon atoms forming the polysiloxane segment (a1)). 
       
     
     
         6 . An active material for negative electrodes of nonaqueous secondary batteries which is obtained by pyrolysis of a dispersion liquid obtained from silicon particles; an organic solvent; and a composite resin (A) which has a silanol group and/or a hydrolysable silyl group and which contains a polysiloxane segment (a1) and a polymer segment (a2) other than the polysiloxane segment (a1). 
     
     
         7 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the pyrolysis is performed so that after the dispersion liquid is sprayed and dried, a dried product obtained thereby is pyrolyzed. 
     
     
         8 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the pyrolysis is performed under spray pyrolysis condition for the dispersion liquid. 
     
     
         9 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the polysiloxane segment (a1) is a polysiloxane segment having a structural unit represented by the following general formula (S-2) and/or the following general formula (S-3), and the content of the polysiloxane segment (a1) is 10 to 95 percent by mass with respect to the composite resin (A) 
       
         
           
           
               
               
           
         
         (in the general formulas (S-2) and (S-3), R 3 , R 4 , and R 5  each independently represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an aryl group, or an aralkyl group having 7 to 12 carbon atoms). 
       
     
     
         10 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the polymer segment (a2) is a vinyl polymer segment. 
     
     
         11 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the composite resin (A) is a composite resin in which the polysiloxane segment (a1) and the polymer segment (a2) are bonded to each other by a structure represented by the following structural formula (S-5) 
       
         
           
           
               
               
           
         
         (in the formula, the carbon atom is a carbon atom forming the polymer segment (a2), and the two silicon atoms are silicon atoms forming the polysiloxane segment (a1)). 
       
     
     
         12 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 , wherein the active material is non-porous. 
     
     
         13 . The active material for negative electrodes of nonaqueous secondary batteries according to  claim 6 , wherein the active material is non-porous. 
     
     
         14 . A negative electrode for nonaqueous secondary batteries which uses the active material for negative electrodes of nonaqueous secondary batteries according to  claim 1 . 
     
     
         15 . A nonaqueous secondary battery which uses the negative electrode for nonaqueous secondary batteries according to  claim 14 .