The present application provides a lithium-ion battery and an apparatus, the lithium-ion battery includes an electrode assembly and an electrolyte, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. A positive active material of the positive electrode sheet includes both Lix1Coy1M11-y1O2-aQ1a and LilNim1Con1M2pM3qO2-bQ2b, a mass ratio of Lix1Coy1M11-y1O2-aQ1a and LilNim1Con1M2pM3qO2-bQ2b is 1:1-9:1. The electrolyte contains an additive A, the additive A is a six-membered nitrogen heterocyclic compound with multiple nitrile groups and with low oxidation potential. The lithium-ion battery according to the present application has excellent cycle performance and storage performance, especially under high temperature and high voltage conditions.