Electrochemical device with improved cycle characteristics

摘要

Disclosed is an electrochemical device. The electrochemical device includes: (a) a composite separator including a porous substrate, a first porous coating layer coated on one surface of the porous substrate, and a second porous coating layer coated on the other surface of the porous substrate; (b) an anode disposed to face the first porous coating layer; and (c) a cathode disposed to face the second porous coating layer. The first and second porous coating layers are each independently composed of a mixture including inorganic particles and a binder polymer. The first porous coating layer is thicker than the second porous coating layer. The electrochemical device has good thermal stability and improved cycle characteristics.

主权项

1. An electrochemical device comprising:
(a) a composite separator comprising a porous substrate, a first porous coating layer coated on one surface of the porous substrate and composed of a mixture comprising inorganic particles and a binder polymer, and a second porous coating layer coated on the other surface of the porous substrate and composed of a mixture comprising inorganic particles and a binder polymer, wherein the first porous coating layer is thicker than the second porous coating layer, wherein interstitial volumes present between the inorganic particles of the first coating layer form a pore structure, and wherein interstitial volumes present between the inorganic particles of the second coating layer form a pore structure; (b) an anode disposed to face the first porous coating layer; and (c) a cathode disposed to face the second porous coating layer, wherein the thicknesses of the first and second porous coating layers satisfy the following relationship 1:
0.11≦(T1−T2)/Ttot≦0.56 wherein T1 and T2 represent the thicknesses of the first and second porous coating layers, respectively, and Ttot represents the total thickness of the first and second porous coating layers, and wherein the total thickness of the first and second porous coating layers is from 1.0 to 20.0 μm.