The present application relates to a secondary battery, which includes: a cathode sheet, an anode sheet, and an electrolyte; the cathode sheet includes a cathode film layer containing a cathode active material, and the anode sheet includes an anode film layer containing an anode active material; and the secondary battery meets a following function relationship: 0.22≤3×(A1/A2)×(B2−B1)/(B1+B2)≤1.55, the parameters are referred to the description; and an electrical device including the secondary battery. The secondary battery in the present application has both good cycle life and excellent fast charging capacity.