SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRIC APPARATUS

A secondary battery includes a positive electrode plate and a non-aqueous electrolyte. The positive electrode plate includes a positive electrode active material including a core and a shell enveloping the core. A chemical formula of the core is LiMnAPRO, where the first coating layer includes a crystalline pyrophosphate LiMPOand/or Mb(PO), the second coating layer includes a crystalline phosphate XPO, and the third coating layer is carbon. The non-aqueous electrolyte includes a first additive including one or more selected from a group consisting of compounds represented by formula 1 and compounds represented by formula 2.