Abstract: An isocyanate electrolyte solution additive containing a sulfamide structural group has a structure of formula I: where R1 and R2 are identical or different, R1 and R2 are each independently selected from methyl, ethyl, butyl, methoxy, methanesulfonyl, ethanesulfonyl, fluorosulfonyl, trifluoromethanesulfonyl, perfluoroethylsulfonyl, benzenesulfonyl, alkyl-containing benzenesulfonyl, cyano/fluorobenzenesulfonyl and alkoxy-containing benzenesulfonyl, and R1 and R2 can be linked to form one of five-membered ring or six-membered ring. In the electrolyte solution additive, sulfonyl and the isocyanate structural group are organically linked, so the electrolyte solution additive has good thermostability, can function as an electrolyte solution stabilizing agent and avoids high temperature discoloration and acid value increase of the electrolyte solution.