SECONDARY BATTERY AND ELECTRIC DEVICE

A secondary battery and an electric device are disclosed. The secondary battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet has a film layer comprising a positive electrode active material that contains transition metal elements, where nickel accounts for at least 85% of the total molar content of the transition metals. The energy per unit area of the positive electrode film layer on one side of the sheet ranges from 15 to 35 mWh/cm. The negative electrode sheet includes a film layer with a carbon-silicon composite active material, in which silicon nanoparticles are attached to a carbon matrix having a carbon skeleton. The combination of a high-nickel positive electrode and a carbon-silicon composite negative electrode enhances the energy density of the secondary battery.