SECONDARY BATTERY ELECTROLYTE SOLUTION, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRICAL DEVICE

An electrolyte solution includes an electrolyte salt, a solvent, and a polyether. A secondary battery includes the electrolyte solution. A method for preparing a secondary battery electrolyte solution includes adding an additive and a cyclic ether compound into a composition containing an electrolyte salt and a solvent, and performing in-situ polymerization for at least 24 hours to obtain the secondary battery electrolyte solution. The additive is a Lewis acid or a Lewis acid precursor.