LITHIUM-ION SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND POWERED DEVICE

The disclosure relates to the field of electrochemistry, and in particular to a lithium-ion secondary battery, a battery module, a battery pack, and a powered device. A lithium-ion secondary battery, includes a bare cell accommodating cavity in which a bare cell group including one or more bare cells A and one or more bare cells B is arranged, wherein the bare cell A includes a first positive electrode sheet including a first positive-electrode active material selected from a single crystal or single crystal-like low-nickel ternary positive electrode material A1, the bare cell B includes a second positive electrode sheet including a second positive-electrode active material and/or a third positive-electrode active material, the second positive-electrode active material is selected from a polycrystalline high-nickel ternary positive electrode material B1, and the third positive-electrode active material is selected from a polycrystalline low-nickel ternary positive electrode material B2.