LITHIUM-ION SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL DEVICE

The present application relates to a lithium-ion secondary battery, where an electrolyte solution of the lithium-ion secondary battery comprises a highly heat-stable salt (M)R(SON)SOR, where the M is a metal ion, R and R are each independently a fluorine atom, an alkyl with 1-20 carbon atoms, a fluoroalkyl with 1-20 carbon atoms, or a fluoroalkoxy with 1-20 carton atoms, the x is 1, 2, or 3, the y is 1, 2, or 3; and a mass percent of the salt in the electrolyte solution is set as k2%; a temperature rise coefficient k1 of the positive electrode sheet satisfies 2.5≤k1≤32, where k1=Cw/Mc, Cw is a positive electrode material load per unit area (mg/cm) on the surface of any side of the positive electrode current collector on which a positive electrode material layer is loaded, and Mc is a carbon content (%) of the positive electrode material layer; and the lithium-ion secondary battery satisfies 0.34≤k2/k1≤8. [0002] The lithium-ion secondary battery of the present application not only has a high energy density, but also has a long life. The present application further relates to a battery module, a battery pack, and a powered device including the lithium-ion secondary battery.