▎ 摘　　要

NOVELTY - Electrochemical device has a positive pole piece having a positive current collector and a positive active material layer containing a positive active material, a negative pole piece having a negative current collector and a negative active material layer containing a negative active material, and an isolation film fixed between the positive pole piece and negative pole piece. The positive active material comprises lithium cobaltate. The electrochemical device satisfies relations involving weight of the positive active material based on total weight of the positive active material layer, gram volume of the positive active material, mass per unit area of the positive active material layer, weight of the negative active material based one total weight of the negative active material layer, gram volume of the negative active material, mass per unit area of the negative active material layer, and charge cut-off voltage of electrochemical device. USE - Electrochemical device used for electronic device (claimed). ADVANTAGE - The electrochemical device reduces charging cut-off voltage and volume expansion of the negative active material layer in charging and discharging process and prevents positive potential of the positive active material caused by adverse effect so as to improve circulation performance of the device.