LITHIUM-ION SECONDARY BATTERY AND RELATED PREPARATION METHOD THEREFOR, BATTERY MODULE, BATTERY PACK, AND DEVICE

A lithium-ion secondary battery (5) and related preparation method thereof, battery module (4), battery pack (1) and apparatus. Specifically, a lithium-ion secondary battery (5) includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator, wherein the positive electrode plate includes a positive electrode current collector and a first positive electrode active material layer and a second positive electrode active material layer sequentially disposed on at least one side of the positive electrode current collector; the lithium-ion secondary battery (5) satisfies: -1 ≤ log(u/v)×w ≤ 15.5, wherein, u is a thickness of the first positive electrode active material layer in microns, v is a thickness of the second positive electrode active material layer in microns, w is a conductivity of the electrolyte at a temperature of 25°C in mS·cm. The lithium-ion secondary battery (5) has excellent performance such as low discharge resistance at low SOC and low gas production at high temperature.