Hybrid Solid Electrolyte Interphase for Dendrite-Free and Uniform Li Deposition

Abstract

Lithium (Li)-metal anode has attracted extensive attention owing to its high theoretical specific capacity (3860 mAh/g), which is more than ten times that of graphite anode (372 mAh/g). However, the notorious reactivity of Li-metal prevents their practical applications due to undesired Li dendrite growth and unstable solid electrolyte interphase (SEI) formation. Here, we developed a facile, cost-effective, and one-step approach for constructing an artificial Li-metal/electrolyte interface by treating Li metal anode with SnF2. As a result, the artificial SEI composed of LiF, Sn, and Sn-Li alloy was formed with higher ionic conductivity and increased Young’s modulus. The higher ionic conductivity and larger Young’s modulus of the artificial layer facilitate fast Li-ion diffusion and suppress Li dendrite growth, respectively. The hybrid artificial SEI showed a synergetic effect of storing Li by a reversible Sn-Li alloy formation and Li plating. The artificial hybrid SEI protected Li symmetrical cells showed outstanding plating/stripping cycles (~2325 hrs) with reduced overpotential compared to the bare Li. The high mass loading NMC cathode coupled with the SEI protected Li full cells exhibited remarkable electrochemical performance such as longer stable cycling, higher capacity retention, and higher capacity at higher rates compared to the bare Li anode.