Lithium secondary battery and method of controlling short resistance thereof

Abstract

Provided is a lithium secondary battery including a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a polymer electrolyte composition having a polymer electrolyte, a non-aqueous organic solvent, and a lithium salt. The content of the polymer electrolyte is 9 to 20 wt %, based on the total weight of the polymer electrolyte composition.

What is claimed is: 
     
         1 . A lithium secondary battery, comprising:
 a positive electrode including a positive electrode active material;   a negative electrode including a negative electrode active material; and   a polymer electrolyte composition including a polymer electrolyte, a non-aqueous organic solvent, and a lithium salt;   wherein the content of the polymer electrolyte is from 9 to 20 wt %, based on the total weight of the polymer electrolyte composition; and   wherein the polymer electrolyte comprises a first monomer of Chemical Formula 1:
   A-polyesterpolyol-B,  [Chemical Formula 1]
 
   wherein,   the polyesterpolyol has a molecular weight of 100 to 10,000,000 and is prepared by a condensation reaction between an alcohol derivative having 2 to 6 terminal OH groups and a dicarboxylic acid derivative,   A and B are connected to the terminal OH groups of the polyesterpolyol, and   A and B are independently selected from CH 2 ═CR—C(═O)—, CH 2 ═CR—C—CH 2 —, CH 2 ═CR—, CH 2 ═CR—O—C(═O)—, CH 2 ═CH—CH 2 —O—, CH 2 ═CH—S(═O) 2 — or CH 2 ═CR—C(═O)—O—CH 2 CH 2 —NH—C(═O)—, wherein R is a C 1 -C 10  hydrocarbon or a C 6 -C 10  aromatic hydrocarbon.   
     
     
         2 . The battery according to  claim 1 , wherein the polymer electrolyte further comprises a second monomer selected from Chemical Formulae 2 to 7:
   CH 2 ═CR1-C(═O)—O—X;  [Chemical Formula 2]
     CH 2 ═CR1-O—X;  [Chemical Formula 3]
     CH 2 ═CR1-O—C(═O)—X;  [Chemical Formula 4]
     CH 2 ═CH—CH 2 —O—X;  [Chemical Formula 5]
     CH 2 ═CH—S(═O) 2 —X;  [Chemical Formula 6]
     CH 2 ═CR1-C(═O)—O—CH 2 CH 2 —NH—C(═O)—O—X,  [Chemical Formula 7]
   wherein,
 R1 is H, a C 1 -C 10  hydrocarbon, or an aromatic hydrocarbon, and 
 X is a C 1 -C 20  hydrocarbon, a halogenated hydrocarbon, an aromatic hydrocarbon or a halogenated aromatic hydrocarbon. 
   
     
     
         3 . The battery according to  claim 1 , wherein the alcohol derivative is selected from the group consisting of polyethyleneglycol, polypropyleneglycol, alkanediol, ethoxylated alkanediol, propoxylated alkanediol, trimethylolpropane, ethoxylated trimethylolpropane, propoxylated trimethylolpropane, ditrimethylolpropane, ethoxylated ditrimethylolpropane, propoxylated ditrimethylolpropane, pentaerythritol, ethoxylated pentaerythritol, propoxylated pentaerythritol, dipentaerythritol, ethoxylated dipentaerythritol, propoxylated dipentaerythritol, bisphenol A, ethoxylated bisphenol A, and propoxylated bisphenol A. 
     
     
         4 . The battery according to  claim 1 , wherein A and B are independently selected from the group consisting of a (meth)acryl group, a vinyl group, a allyl group, a vinylsulfonyl group, and a urethane(meth)acryl group. 
     
     
         5 . The battery according to  claim 1 , wherein the lithium salt is selected from the group consisting of LiPF 6 , LiBF 4 , LiBOB (lithium bisoxalato barate), LiSbF 6 , LiAsF 6 , LiClO 4 , LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiN(C x F 2x+1 SO 2 )(C y F 2x+1 SO 2 ) (where, x and y are natural numbers), LiSO 3 CF 3 , and a combination thereof. 
     
     
         6 . The battery according to  claim 1 , wherein the non-aqueous organic solvent is from the group consisting of a carbonate, an ester, an ether, a ketone, a nitrile, and a combination thereof. 
     
     
         7 . The battery according to  claim 1 , wherein the negative electrode further includes a binder comprising a styrene-butadiene rubber. 
     
     
         8 . The battery according to  claim 1 , wherein the content of the polymer electrolyte is from 7 wt % to 20 wt %, based on the total weight of the polymer electrolyte composition. 
     
     
         9 . The battery according to  claim 8 , wherein the negative electrode further includes a binder comprising polyvinylidenefluoride. 
     
     
         10 . A polymer electrolyte composition for use in a lithium secondary battery, comprising:
 a polymer electrolyte;   a non-aqueous organic solvent; and   a lithium salt, wherein, the content of the polymer electrolyte is from 9 to 20 wt %, based on the total weight of the polymer electrolyte composition,   the polymer electrolyte comprises a first monomer of Chemical Formula 1:
   A-polyesterpolyol-B,  [Chemical Formula 1]
 
   wherein,   the polyesterpolyol has a molecular weight of 100 to 10,000,000 and is prepared by a condensation reaction between an alcohol derivative having 2 to 6 terminal OH groups and a dicarboxylic acid derivative,   A and B are connected to the terminal OH groups of the polyesterpolyol, and   A and B are independently selected from CH 2 ═CR—C(═O)—, CH 2 ═CR—C—CH 2 —, CH 2 ═CR—, CH 2 ═CR—O—C(═O)—, CH 2 ═CH—CH 2 —O—, CH 2 ═CH—S(═O) 2 — or CH 2 ═CR—C(═O)—O—CH 2 CH 2 —NH—C(═O)—, wherein R is a C 1 -C 10  hydrocarbon or a C 6 -C 10  aromatic hydrocarbon.   
     
     
         11 . The polymer electrolyte composition according to  claim 10 , wherein the polymer electrolyte further comprises a second monomer selected from Chemical Formulae 2 to 7:
   CH 2 ═CR1-C(═O)—O—X;  [Chemical Formula 2]
     CH 2 ═CR1-O—X;  [Chemical Formula 3]
     CH 2 ═CR1-O—C(═O)—X;  [Chemical Formula 4]
     CH 2 ═CH—CH 2 —O—X;  [Chemical Formula 5]
     CH 2 ═CH—S(═O) 2 —X;  [Chemical Formula 6]
     CH 2 ═CR1-C(═O)—O—CH 2 CH 2 —NH—C(═O)—O—X,  [Chemical Formula 7]
   wherein,
 R1 is H, a C 1 -C 10  hydrocarbon, or an aromatic hydrocarbon, and 
 X is a C 1 -C 20  hydrocarbon, a halogenated hydrocarbon, an aromatic hydrocarbon or a halogenated aromatic hydrocarbon. 
   
     
     
         12 . The polymer electrolyte composition according to  claim 10 , wherein the polyesterpolyol is represented by Chemical Formula 20: 
       
         
           
           
               
               
           
         
         wherein,
 X, Y, and Z are independently selected from the group consisting of a multi-valent alkylene oxide, an alkylene imide, and an alkylene, 
 x, y and z are independently selected from integers ranging from 1 to 20, and 
 l, m, and n are independently selected from integers ranging from 0, 1, or more, such that the polyesterpolyol has a weight average molecular weight of about 25000.