Enhanced Cycle Stability of Rechargeable Li-O2 Batteries by the Synergy Effect of a LiF Protective Layer on the Li and DMTFA Additive.

Abstract

Li metal is an ideal anode for rechargeable Li-O2 batteries because of its large theoretical capacity (3860 mAh g-1). However, problems with the growth of dendrites and reaction with electrolytes and moisture during cycling have prevented its practical application. Herein, we report that the use of a 2 wt % N,N-dimethyltrifluoroacetamide (DMTFA) additive in a dimethyl sulfoxide (DMSO) electrolyte with a LiF layer on the Li anode allows for good cycling performance in Li-O2 batteries. Indeed, a Li-O2 cell with a multiwalled carbon nanotube (MWCNT) cathode, 1.0 M LiNO3/DMTFA + DMSO (2:98 v/v) electrolyte, and a LiF layer on the Li anode could be cycled 92 times at a current density of 1000 mA g-1 with a 1000 mAh g-1.