▎ 摘　　要

NOVELTY - The device has an electrode assembly that is provided with a positive electrode sheet. The positive electrode sheet comprises a positive current collector. A positive electrode active material layer is arranged on the positive current collector, and comprises a positive electrode active material and graphene. A portion of the graphene is arranged on a surface of particles of the positive active material. The positive electrode active material includes primary particles with preset value. The positive electrode active material includes secondary particles with preset value. A mass percentage of the graphene is more than or equal to 0.05% and less than 0.5% based on a mass of the positive electrode active material layer. USE - Electrochemical device e.g. lithium ion battery for electronic device (claimed). Uses include but are not limited to notebook computer, electronic book player, portable phone, portable facsimile machine, portable copier, portable printer, headphone, video recorder, liquid crystal TV, handheld cleaner, portable CD player, mini-disc, transceiver, electronic organizer, calculator, motorcycle, power-assisted bicycle, and lighting fixture. ADVANTAGE - The compaction density of the positive electrode active material layer is improved, the energy density of the electrochemical device is improved, the polarization is reduced and the charging speed of the electrochemical device is improved.