Lithium secondary battery and battery module, battery pack, and electric apparatus containing same

A lithium secondary battery, comprising:

• a positive electrode, a negative electrode, and an electrolyte;
• wherein
• the positive electrode comprises a positive-electrode active substance layer, the positive-electrode active substance layer contains a pre-lithiation agent, and a molecular formula of the pre-lithiation agent is LixNiaCu1−a−bMbO2, wherein 1≤x≤2, 0<a<1, and 0≤b<0.1, and M is selected from one or more of Zn, Sn, Mg, Fe, and Mn;
• the negative electrode comprises a negative-electrode active substance layer, the negative-electrode active substance layer contains a first negative-electrode active substance and a second negative-electrode active substance, wherein the first negative-electrode active substance is graphite, and the second negative-electrode active substance is selected from one or more of Si, SiOn (0<n<2), and SiC;
• the electrolyte contains fluoroethylene carbonate (FEC);
• and
• the lithium secondary battery satisfies 0.2×WSi≤WFEC≤7.5%−0.6×WL, wherein WFEC is a weight percentage of the FEC in the electrolyte, WSi is a weight percentage of element silicon contained in the second negative-electrode active substance in the negative-electrode active substance layer, and WL is a weight percentage of the pre-lithiation agent in the positive-electrode active substance layer.