Organic/Inorganic Composite Electrolyte and Electrochemical Device Prepared Thereby

Abstract

Disclosed is an electrode whose surface includes an organic/inorganic composite porous coating layer comprising porous inorganic particles and a binder polymer, wherein the porous inorganic particles have pores having such a size that lithium ions (Li+) solvated in an electrolyte solvent can pass therethrough. A method for manufacturing the electrode and an electrochemical device using the electrode are also disclosed. The organic/inorganic composite porous coating layer formed on the electrode according to the present invention provides an additional pathway for lithium ion conduction due to a plurality of pore structures present in the porous inorganic particles. Thus, when the organic/inorganic composite porous coating layer is used instead of a conventional polymer-based separator in a battery, the battery can provide improved quality and an increased energy density per unit weight due to a reduced weight of the organic/inorganic composite porous coating layer.

1 . An electrode whose surface comprises an organic/inorganic composite porous coating layer comprising porous inorganic particles and a binder polymer, wherein the porous inorganic particles have pores having such a size that lithium ions (Li + ) solvated in an electrolyte solvent can pass therethrough. 
   
   
       2 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have pores with an average diameter of 2 nm or more. 
   
   
       3 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have pores with an average diameter of 50 nm˜1 μm. 
   
   
       4 . The electrode as claimed in  claim 1 , wherein the pores in the porous inorganic particles are interconnected among themselves. 
   
   
       5 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have a porosity of 30˜95%. 
   
   
       6 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have a density of 1˜4 g/cc and a surface area of 10˜50 m 2 /g. 
   
   
       7 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have the pore structure by dispersing inorganic precursors and heat-decomposable compounds that are pyrolyzed at a temperature lower than a melting temperature of the inorganic particles in a dispersion medium, misting the inorganic precursor solution, and performing thermal decomposition and crystallization processes. 
   
   
       8 . The electrode as claimed in  claim 1 , which comprises an organic/inorganic composite porous coating layer formed by coating a mixture of the porous inorganic particles and the binder polymer onto a surface of an electrode comprising electrode active material particles bound to a collector while forming a pore structure, wherein the porous inorganic particles are interconnected and fixed among themselves by the binder polymer, and interstitial volumes among the porous inorganic particles form a pore structure. 
   
   
       9 . The electrode as claimed in  claim 1 , wherein the organic/inorganic composite porous coating layer serves as a separator preventing a cathode and an anode from being in direct contact with each other and permitting lithium ions (Li + ) to pass therethrough. 
   
   
       10 . The electrode as claimed in  claim 1 , wherein the porous inorganic particle is at least one particle selected from the group consisting of: (a) inorganic particles having a dielectric constant of 5 or more; and (b) inorganic particles having lithium ion conductivity. 
   
   
       11 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles have a size of 0.01˜10 μm. 
   
   
       12 . The electrode as claimed in  claim 1 , wherein the binder polymer has a solubility parameter of 15˜45 MPa 1/2 . 
   
   
       13 . The electrode as claimed in  claim 1 , wherein the porous inorganic particles and the binder polymer are used in a weight ratio of 10:90˜99:1. 
   
   
       14 . The electrode as claimed in  claim 1 , wherein the organic/inorganic composite porous coating layer has a thickness of 1˜100 μm. 
   
   
       15 . An electrochemical device comprising a cathode, an anode and an electrolyte, wherein either or both of the cathode and the anode are the electrode as defined in  claim 1 . 
   
   
       16 . The electrochemical device as claimed in  claim 15 , which further comprises a microporous separator. 
   
   
       17 . The electrochemical device as claimed in  claim 15 , which is a lithium secondary battery. 
   
   
       18 . A method for manufacturing the electrode having an organic/inorganic composite porous coating layer as defined in  claim 1 , the method comprising the steps of:
 (a) dispersing inorganic precursors and heat-decomposable compounds in a dispersion medium, misting the inorganic precursor solution, and performing a thermal decomposition and a crystallization processes, to thereby prepare porous inorganic particles;   (b) adding and mixing the porous inorganic particles to a polymer solution in which a binder polymer is dissolved; and   (c) coating the mixture of step (b) onto a preliminarily formed electrode and drying the coating layer.   
   
   
       19 . The method as claimed in  claim 18 , wherein heat-decomposable compounds are polymer or foaming agent decomposed or pyrolyzed at a temperature lower than a melting point of the inorganic compound. 
   
   
       20 . The method as claimed in  claim 18 , wherein the thermal decomposition of step (a) is performed at a temperature lower than the melting point of the inorganic compound and higher than a decomposition temperature of the heat-decomposable compounds.