▎ 摘　　要

NOVELTY - Electrochemical device comprises a cathode and an electrolyte. The cathode includes a cathode current collector. An undercoat layer includes a volume expansion resin and formed on at least one surface of cathode current collector. A cathode active material layer includes a cathode active material and formed on undercoat layer. The electrolyte includes propyl propionate. The volume expansion resin includes polyethylene, polypropylene, polyethylene vinyl acetate and/or polypropylene. The volume expansion resin includes thermally expandable microspheres. The primer layer includes conductive agent and binder. and the conductive agent includes carbon nanotubes, graphene and/or carbon black. The binder includes polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, styrene-butadiene rubber and/or fluorine-containing rubber. USE - The electrochemical device is useful in electronic device (claimed), and for lithium ion battery. ADVANTAGE - The device has improved safety performance under thermal runaway, which actively reduces voltage drop under low-temperature storage. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for electronic device.