COMPOSITE diaphragm FOR SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY CONTAINING SAME

Abstract

The invention provides a composite diaphragm for a secondary battery and a lithium secondary battery containing the same. The composite diaphragm including: a porous substrate; and a coating layer, formed on the porous substrate, by thermally curing aqueous slurry including inorganic particles, first binder particles, a second binder, and a thermal curing agent, wherein the first binder particlescontain a copolymer of a monomer mixture including an acrylamide-based monomer, a vinyl cyanide-based monomer, an acrylic monomer having a carboxyl group, and an acrylic monomer having a hydroxyl group, and a lithium secondary battery including the same.

Description

technical field [0001] The following disclosure relates to a composite separator for a secondary battery, and a lithium secondary battery including the same. Background technique [0002] In recent years, in view of the high-capacity and high-output trends of secondary batteries, the demand for high strength, high permeability, and thermal stability of separators, and improved characteristics of separators in terms of electrical safety during charge and discharge of secondary batteries has grown . Lithium secondary batteries are required to have high mechanical strength to improve safety during battery manufacturing and during battery use, and high permeability and high thermal stability to improve capacity and output. [0003] In order to ensure the safety and improve the lithium secondary battery, the physical and electrochemical safety of the separator is particularly important among various members included in the lithium secondary battery. For example, when the therma...

AI Technical Summary

Problems solved by technology

However, heat setting is performed during the formation of polyolefin-based microporous membranes, and during this process, the membranes are partially melted so that the surface pores of the porous membranes are closed and damaged, thereby greatly increasing the air-permeable time

[0006] In addition, since conventional separators including inorganic layers use organic solvents in the manufacturing process, coating methods based on adhesive compositions dissolved in organic solvents There are some problems in

First, when the organic solvent is volatilized during the drying process, the binder dissolved in the organic solvent forms a gel, thereby creating a solvent-impermeable space, resulting in an imbalance of the organic / inorganic coating, and this phenomenon may degrade battery characteristics.

In addition, explosion-proof equipment is required, and by-products that are harmful to the environment or humans will occur during the work process

Also, there is a problem in that the pores of the porous polymer substrate are closed in the state where the adhesive is dissolved in the organic solvent

As separators thereof, separators for electrochemical devices having improved adhesive strength with porous substrates to have excellent heat resistance and strength have been proposed, however, the degree of thermal and electrochemical safety of the separators is still insufficient for use in To ensure the safety of the battery, there is still a need to improve battery capacity

Images