Lithium Ion Secondary Battery

Abstract

A lithium ion secondary battery includes a negative electrode portion, a porous layer formed on at least one surface of the negative electrode portion, and a positive electrode portion. The porous layer includes a polymer binder and inorganic fine particles dispersed on the polymer binder. The positive electrode portion is bonded onto the porous layer through an adhesive portion arranged continuously or discontinuously. The adhesive portion includes a thermoplastic polymer having a viscosity ranging from 2000 cPs to 95000 cPs at 25° C., and a ratio of an area occupied by the adhesive portion ranges from 0.02% to 10% based on an area of one surface of the positive electrode portion. A lithium ion secondary battery including an electrode assembly which has excellent adhesion durability without impairing ionic conductivity between electrodes is also provided.

Dependencies are inferred from the claim text.