A compatible carbonate electrolyte with lithium anode for high performance lithium sulfur battery

摘要

We report a new carbonate electrolyte of 1?M LiFSI dissolved in the EMC/FEC (70/30, v/v) solvent for lithium metal based batteries. Favorable LiF-rich SEI layer is formed on Li anode to suppress side reactions under the synergistic effect of LiFSI and FEC. Thus, the dendrite-free Li morphology and high Coulombic efficiency for Li plating/stripping can be obtained with improved cycle stability compared with conventional LiPF6/EC-DMC electrolyte. Li | S@pPAN cell assembled with the new electrolyte shows quite low lithium ion transfer resistance, excellent long cycle stability and rate performance. A high discharge capacity of 1270?mAh g?1remains after 1000 cycles at 2?C, with an inappreciable capacity decay of 0.0015% per cycle. Due to the low interface impedance and high Li+diffusion coefficient, a capacity of 1210?mAh g?1even at 10?C can be maintained. This deliberately designed electrolyte offers new insights into the understanding of interfacial stability between electrolyte and Li anode. Furthermore, our work offers a new approach towards high energy-density and high rate Li-S battery.