Vinylidene carbonate drived ultra-stable artificial SEI for lithium metal anode with ultra-long life

Lithium metal is regarded as a highly promising anode material for rechargeable batteries, owing to its exceptional specific capacity and energy density. Solid electrolyte interface (SEI) is a key factor influencing the stability of lithium metal anode. Nonetheless, a notable obstacle persists in the unregulated electrodeposition of lithium and the erratic development of the synthetic solid electrolyte interface (SEI) throughout cycling, leading to premature cell malfunction and safety hazards. This study introduces an artificial SEI for lithium metal characterized by consistent Li-ion conveyance and superior mechanical durability to tackle these pivotal challenges. The addition of Vinylidene carbonate (VC) introduces strong polar groups to the SEI, which alters the electron transfer kinetics and facilitates the cleavage of bis (trifluoromethanesulfonimide) (LiTFSI). Consequently, an LiF-rich SEI is formed, which facilitates rapid Li-ion transport and suppresses lithium dendrite growth. The mechanical strength of artificial SEI can be effectively increased, and the risk of lithium dendrite growth reduced by LLZTO. Lithium symmetric cells modified by this artificial SEI can cycle stably at ultra-high current densities (25 mA cm −2 , 25 mAh cm −2 ) for >14,000 h, representing the most prolonged reported cycling duration for lithium metal batteries under such elevated current densities (25 mA cm −2 ). The full cell with LiFePO 4 (LFP) cathode still exhibits a coulombic efficiency of 99 % after 1000 charge/discharge cycles at 0.5C under low-temperature conditions (−2 °C). The rational design not only provides a new strategy for constructing artificial SEI, but also suggests a new approach for the optimization of other battery systems.