Efficient Mineralization of Lithium Bis(pentafluoroethanesulfonyl)imide and Related Electrolyte Fluorochemicals Using Superheated Water

Abstract

Lithium bis(pentafluoroethanesulfonyl)imide, Li-[N(SO 2 C 2 F 5 ) 2 ], a typical fluorochemical aimed at better electrochemical performance of battery electrolytes, in superheated water was studied for its waste treatment. When Li[N(SO 2 C 2 F 5 ) 2 ] was reacted in pure superheated water at 300 °C, little F − ions were produced. In contrast, complete mineralization of the fluorine, sulfur, and nitrogen atoms in Li[N(SO 2 C 2 F 5 ) 2 ] was achieved when the reaction was performed in the presence of KMnO 4 . Specifically, when Li[N(SO 2 C 2 F 5 ) 2 ] was treated for 18 h with 158 mM of KMnO 4 , the F − and SO 4 2− yields were 101 and 99%, respectively, and the sum of the NO 3 − and NO 2 − yields was 101%. In the gas phase, trace CO 2 was detected and no CHF 3 , which has high global warming potential, was formed. Furthermore, the fluorine, sulfur, and nitrogen atoms in the analogues K[N(SO 2 C 4 F 9 ) 2 ] and K[N(SO 2 CF 2 ) 2 CF 2 ] also underwent complete mineralization using the same approach.