In situ generated air-stable inorganic-rich SEI of lithium anodes for dendrite-free lithium metal batteries

Abstract

Lithium metal batteries (LMBs) are appealing candidates for next-generation energy storage systems. However, their poor air stability and unstable lithium metal interface are limiting factors for their wide application. Herein, we developed an artificial inorganic-rich solid electrolyte interphase (SEI) through a simple hot rolling process, with LiF, LiOH, Li₂O, and Li_xSiF_y phases uniformly and continuously distributed to rapidly conduct Li⁺ and the Mg metal phase serving as nucleation sites to guide Li⁺ for fast and uniform deposition. Additionally, the dense SEI blocked air and improved the air durability of MSF@Li. The inorganic-rich SEI with high-ion flux provided stable cycling for over 1500 h at a current density of 1 mA cm⁻² and a capacity of 1 mA h cm⁻², with a polarization voltage of approximately 30 mV in Li‖Li symmetric cells. Even when the current density was increased to 10 mA cm⁻² (1 mA h cm⁻²), the symmetric cells maintained stable cycling for 250 hours. Notably, the symmetric cell cycled for 350 h at 2 mA cm⁻² and 2 mA h cm⁻² after the MSF@Li anode was exposed to air for 30 minutes. Furthermore, the MSF@Li‖LFP full cell exhibited good cycling stability for more than 420 cycles with a discharge capacity retention rate of 95.1% and an average coulombic efficiency of 99.4% at 1 C. This work provides a new practical route and a simple process for constructing composite Li metal anodes with superior performance.