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

Rapid inactive lithium accumulation and severe lithium dendrite growth critically limit the cycle life of metallic lithium anodes. 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 ions, robust inorganic-rich electrode interphases could be generated at both the anode and the cathode, which is conducive to enhanced kinetics and structural stability of the 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 and improve the ability of solvents to resist nucleophilic attack. Consequently, the assembled Li//LiFePO₄ full cells with 2.0 wt% of the 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 that the 1,3-dithiane additive could induce a long-lifespan lithium-metal battery.