Secondary battery and device comprising the same

A secondary battery comprising a positive electrode plate, a negative electrode plate and an electrolyte, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material, and the electrolyte comprises an electrolyte salt, an organic solvent, and an additive, wherein

• the negative electrode active material comprises a silicon-based material;
• the organic solvent comprises ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC),
• a mass ratio of EC in the organic solvent is 5% to 20%, a mass ratio of DEC in the organic solvent is 5% to 20%, and a mass ratio of EMC in the organic solvent is 55%-65%;
• the additive comprises an additive A and an additive B;
• and
• the additive A is selected from one or more of compounds represented by Formula 2:
• wherein
• R21, R22, R23, and R24 are each independently selected from the group consisting of H, F, Cl, Br, I, substituted or unsubstituted C1-C10 chain alkyls, substituted or unsubstituted C1-C10 chain alkenyls, substituted or unsubstituted C1-C10 chain alkynyls, C1-C10 aliphatic groups, substituted or unsubstituted C3-C9 cyclic alkyls, substituted or unsubstituted C1-C10 alkoxys, substituted or unsubstituted C6-C20 aryls, and substituted or unsubstituted C3-C20 heteroaryls;
• and the substituent is selected from one or more of the group consisting of F, Cl, and Br;
• and
• the additive B is selected from one or more of compounds-represented by Formula 3:
• wherein R31, R32, R33, R34, R35, R36, R37, R38 and R39 are independently selected from one or more the group consisting of substituted or unsubstituted C1-C20 alkyls, substituted or unsubstituted C2-C20 alkenyls, substituted or unsubstituted C2-C20 alkynyls, and] substituted or unsubstituted C6-C20 aryls, and a substituent selected from one or more of the group consisting of F, Cl, and Br;
• wherein a mass ratio of the additive A in the electrolyte is equal to or greater than 0.05% to less than or equal to 1%;
• wherein a mass ratio of the additive B in the electrolyte is equal to or greater than 0.1% to less than or equal to 2%;
• wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector, and
• wherein the positive electrode film comprises a positive electrode active material, and the positive electrode active material comprises a lithium nickel cobalt manganese oxide.