Separator and lithium-ion battery

Abstract

The present invention provides a separator and a lithium-ion battery. The separator comprises a porous substrate, and a first coating layer arranged on at least one surface of the porous substrate, wherein the first coating layer comprises an aromatic polyamide. An aramid coating layer is used in the present invention, the aromatic polyamide in the aramid coating layer swells or plasticizes under the action of a solvent and a lithium salt in the electrolyte at high temperature or normal temperature, to increase the elongation of the separator, while improving the safety performance of the lithium-ion battery by interaction between the aramid coating layer and the electrode active material or the binder.

What is claimed is: 
     
         1 . A lithium-ion battery, comprising:
 a separator; and   an electrolyte; wherein the separator comprises a porous substrate and a first coating layer, the first coating comprises an aromatic polyamide, and the electrolyte comprises a linear ester compound.   
     
     
         2 . The lithium-ion battery according to  claim 1 , wherein the first coating layer is arranged on at least one surface of the porous substrate. 
     
     
         3 . The lithium-ion battery according to  claim 1 , wherein the separator further comprises a second coating layer, and the second coating layer comprises inorganic particles, a polymer or a combination thereof. 
     
     
         4 . The lithium-ion battery according to  claim 1 , wherein the first coating layer further comprises inorganic particles, a polymer or a combination thereof. 
     
     
         5 . The lithium-ion battery according to  claim 3 , wherein the inorganic particles comprise one or more selected from a group consisting of silicon oxide, alumina, titanium oxide, zinc oxide, magnesium oxide, boehmite, magnesium hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, lithium lanthanum titanate. 
     
     
         6 . The lithium-ion battery according to  claim 4 , wherein the inorganic particles comprise one or more selected from a group consisting of silicon oxide, alumina, titanium oxide, zinc oxide, magnesium oxide, boehmite, magnesium hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, lithium lanthanum titanate. 
     
     
         7 . The lithium-ion battery according to  claim 3 , wherein the polymer comprises one or more selected from a group consisting of polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, polyhexafluoropropylene, polyacrylonitrile. 
     
     
         8 . The lithium-ion battery according to  claim 4 , wherein the polymer comprises one or more selected from a group consisting of polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, polyhexafluoropropylene, polyacrylonitrile. 
     
     
         9 . The lithium-ion battery according to  claim 1 , wherein the aromatic polyamide comprises one or more selected from a group consisting of para-aramid, meta-aramid, semi-aromatic polyamide, copolyaromatic polyamide. 
     
     
         10 . The lithium-ion battery according to  claim 9 , wherein the copolyaromatic polyamide is prepared by polymerizing a diamine aromatic compound with a dibasic acid chloride aromatic compound. 
     
     
         11 . The lithium-ion battery according to  claim 10 , wherein the diamine aromatic compound comprises one or more selected from a group consisting of the compounds represented by the following chemical formulas: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         12 . The lithium-ion battery according to  claim 10 , wherein the dibasic acid chloride aromatic compound comprises one or more selected from a group consisting of the compounds represented by the following chemical formulas: 
       
         
           
           
               
               
           
         
       
     
     
         13 . The lithium-ion battery according to  claim 1 , wherein the polydispersity index Mw/Mn of the aromatic polyamide is between 5 and 100, and the molecular weight thereof is between 1000 and 1000000. 
     
     
         14 . The lithium-ion battery according to  claim 1 , wherein the first coating layer has a thickness of 0.5 to 20 μm. 
     
     
         15 . The lithium-ion battery according to  claim 1 , wherein the linear ester compound comprises one or more selected from a group consisting of methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl propionate, methyl acetate. 
     
     
         16 . The lithium-ion battery according to  claim 1 , wherein the electrolyte further comprises a cyclic ester compound, and the cyclic ester compound comprises one or more selected from a group consisting of vinyl carbonate, propylene carbonate, butylene carbonate, 1,4-butyrolactone, ethylene carbonate, propylene carbonate, butylene carbonate, vinyl ethylene carbonate. 
     
     
         17 . The lithium-ion battery according to  claim 1 , wherein the electrolyte comprises a lithium salt, and the lithium salt comprises one or more selected from a group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(oxalate)borate, lithium oxalyldifluroborate, lithium bis(fluorosulfonyl)imide, bistrifluoromethanesulfonimide lithium.