Abstract: Embodiments described herein are directed to a non-aqueous electrolyte solution that may include a lithium salt, an organic solvent, and additives. The additives may include an additive A and an additive B. Additive A may be one or more of the substances represented by the structural general formula where 0?n?3, R1 may be selected from alkylene, alkyleneoxy, fluoroalkylene, fluoroalkyleneoxy, alkenylene or fluoroalkenylene, and R2 and R3 may be independently selected from hydrogen, phenyl, alkynyl, alkynyloxy, alkyl, alkoxy, fluoroalkyl, fluoroalkoxy, alkenyl or fluoroalkenyl. Additive B may be a boron-containing lithium salt.

Abstract: Disclosed is a secondary battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte comprises a lithium salt, an organic solvent, and an additive, wherein the additive comprises a fluorinated compound that accounts for 5-20% of the total mass of the electrolyte, and a polynitrile compound that accounts for 0.2-4% of the total mass of the electrolyte and a sulfate compound that accounts for 0.3-5% of the total mass of the electrolyte; and the negative electrode has a compacted density of not less than 1.55 g/cm3. When the secondary battery is used, the battery can still have both a high temperature characteristic and a low temperature charging ability under the conditions of a higher negative electrode density, thereby having market application prospects, and overcoming the problem of the performance of existing secondary batteries deteriorating when the compacted density of a negative electrode is improved.