SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRIC DEVICE

Provided are a secondary battery, a battery module, a battery pack, and an electric device. The secondary battery includes: a positive electrode sheet and a non-aqueous electrolyte, where the positive electrode sheet includes a cathode active material with a core-shell structure, and the cathode active material includes a core and a shell covering the core; the core has a chemical formula of LiMnAPRO; where the first coating layer includes a crystalline pyrophosphate LiMPOand/or a crystalline pyrophosphate M(PO), the second coating layer includes a crystalline phosphate XPO, and the third coating layer is carbon; and the non-aqueous electrolyte includes a first lithium salt and a first additive, where the first lithium salt includes one or more selected from the group consisting of LiN(CFSO)(CFSO) and Li(FSO)N, where m and n each are a positive integer.