SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL APPARATUS

Provided are a secondary battery, a battery module, a battery pack, and an electrical apparatus. The secondary battery comprises a positive electrode plate and a non-aqueous electrolyte solution, where the positive electrode plate comprises a positive electrode active material having a core-shell structure and comprising an inner core and a shell cladding the inner core, where the inner core has a chemical formula of LiMnAPRO, a first cladding layer comprises crystalline pyrophosphates LiMPOand/or M(PO), a second cladding layer comprises a crystalline phosphate XPO, and a third cladding layer is carbon; and the non-aqueous electrolyte solution comprises a first additive comprising one or more compounds in the group consisting of a compound represented by formula 1, a compound represented by formula 2, and a compound represented by formula 3, thereby improving rate performance, cycling performance, and high-temperature stability of a lithium manganese phosphate secondary battery.