A lithium-ion battery, comprising an electrode assembly and an electrolyte, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator; wherein a positive active material of the positive electrode sheet comprises both Li x1 Co y1 M1 1-y1 O 2-a Q1 a and Li 1 Ni m1 Co n1 M2 p M3 q O 2-b Q2 b, a mass ratio of Li x1 Co y1 M1 1-y1 O 2-a Q1 a and Li 1 Ni m1 Co n1 M2 p M3 q O 2-b Q2 b is 1:1-9:1; wherein 0.5≤x1≤1.2, 0.8≤y1<1.0, 0≤a≤0.1, M1 is selected from one or more of Al, Ti, Zr, Y, and Mg, and Q1 is selected from one or more of F, Cl, and S; 0.5≤l≤1.2, 0.33≤m1≤0.85, 0.1≤n1≤0.33, 0.1≤p≤0.33, 0≤q≤0.1, and m1+n1+p+q=1, 0≤b≤0.1, M2 is selected from one or two of Mn and Al, M3 is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Y, and Nb, and Q2 is selected from one or more of F, Cl, and S; the electrolyte comprises an additive A, the additive A is selected from one or more of compounds represented by Formula I-1, Formula I-2, and Formula I-3; in the Formula I-1, Formula I-2 and Formula I-3: R 1, R 2, R 3 and R 4 each are independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1 -C 12 alkyl group, a substituted or unsubstituted C 1 -C 12 alkoxyl group, a substituted or unsubstituted C 1 -C 12 amido group, a substituted or unsubstituted C 2 -C 12 alkenyl group, a substituted or unsubstituted C 2 -C 12 alkynyl group, a substituted or unsubstituted C 6 -C 26 aryl group, and a substituted or unsubstituted C 2 -C 12 heterocyclyl group, wherein a substituent is selected from one or more of a halogen atom, a nitrile group, a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, and C 1 -C 6 alkoxyl group; x, y and z each are independently selected from an integer of 0-8; m, n and k each are independently selected from an integer of 0-2. a positive active material of the positive electrode sheet comprises both Li x1 Co y1 M1 1-y1 O 2-a Q1 a and Li 1 Ni m1 Co n1 M2 p M3 q O 2-b Q2 b, a mass ratio of Li x1 Co y1 M1 1-y1 O 2-a Q1 a and Li 1 Ni m1 Co n1 M2 p M3 q O 2-b Q2 b is 1:1-9:1; wherein 0.5≤x1≤1.2, 0.8≤y1<1.0, 0≤a≤0.1, M1 is selected from one or more of Al, Ti, Zr, Y, and Mg, and Q1 is selected from one or more of F, Cl, and S; 0.5≤l≤1.2, 0.33≤m1≤0.85, 0.1≤n1≤0.33, 0.1≤p≤0.33, 0≤q≤0.1, and m1+n1+p+q=1, 0≤b≤0.1, M2 is selected from one or two of Mn and Al, M3 is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Y, and Nb, and Q2 is selected from one or more of F, Cl, and S; the electrolyte comprises an additive A, the additive A is selected from one or more of compounds represented by Formula I-1, Formula I-2, and Formula I-3; in the Formula I-1, Formula I-2 and Formula I-3: R 1, R 2, R 3 and R 4 each are independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1 -C 12 alkyl group, a substituted or unsubstituted C 1 -C 12 alkoxyl group, a substituted or unsubstituted C 1 -C 12 amido group, a substituted or unsubstituted C 2 -C 12 alkenyl group, a substituted or unsubstituted C 2 -C 12 alkynyl group, a substituted or unsubstituted C 6 -C 26 aryl group, and a substituted or unsubstituted C 2 -C 12 heterocyclyl group, wherein a substituent is selected from one or more of a halogen atom, a nitrile group, a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, and C 1 -C 6 alkoxyl group; x, y and z each are independently selected from an integer of 0-8; m, n and k each are independently selected from an integer of 0-2.