| abstract |
The present application provides an electrochemical energy storage device. The electrochemical energy storage device includes a positive electrode sheet comprising a positive electrode active material layer, a negative electrode sheet comprising a negative electrode active material layer, a separator placed between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The anode active material layer includes a silicon-based material. The electrolyte solution includes electrolyte salt, organic solvent and additives. The additives include sulfonate cyclic quaternary ammonium salts, polynitrile compounds, and fluoroethylene carbonate and/or vinylene carbonate. Under the combined action of electrolyte additives, a dense and uniform passivation film with high ionic conductivity can be formed on the surface of the positive and negative electrodes of the electrochemical energy storage device, which can avoid the continuous occurrence between the electrolyte and the positive and negative electrodes. The oxidation and reduction reactions of silicon-based materials are suppressed, and the electrochemical energy storage device has good high-temperature cycle performance and high-temperature storage performance. |