A thioether additive as interfacial regulator for ultra-stable lithium metal batteries

Abstract Rapid inactive lithium accumulation and severe lithium dendrite growth critically limit the cycle life of metallic lithium anode. Herein, cyclic thioether 1,3-dithiane is reported as a novel electrolyte additive for fabricating ultra-stable lithium metal batteries. Through the preferential decomposition of 1,3-dithiane additive and PF6− anion ion, robust inorganic-rich electrode interphases could generate at both anode and cathode, which is conducive to enhanced kinetics and structural stability of electrode interface, endowing alleviated active lithium loss and dendrite-free lithium deposition. Moreover, 1,3-dithiane would react with lithium alkylide to reduce the organic component in solid electrolyte interphases (SEI) and improve the ability of solvents to resist nucleophilic attack. Consequently, the assembled Li//LiFePO4 full cells with 2.0 wt.% 1,3-dithiane-containing electrolyte exhibit a significantly improved capacity retention of 83.6% after 3300 cycles at a current rate of 1.0 C, which highlights the 1,3-dithiane additive could induce a long-lifespan lithium metal battery.