Lithium metal anodes have attracted extensive attention owing to their high theoretical specific capacity. However, the notorious reactivity of lithium prevents their practical applications, as evidenced by the undesired lithium dendrite growth and unstable solid electrolyte interphase formation. Here, we develop a facile, cost-effective and one-step approach to create an artificial lithium metal/electrolyte interphase by treating the lithium anode with a tin-containing electrolyte. As a result, an artificial solid electrolyte interphase composed of lithium fluoride, tin, and the tin-lithium alloy is formed, which not only ensures fast lithium-ion diffusion and suppresses lithium dendrite growth but also brings a synergistic effect of storing lithium via a reversible tin-lithium alloy formation and enabling lithium plating underneath it. With such an artificial solid electrolyte interphase, lithium symmetrical cells show outstanding plating/stripping cycles, and the full cell exhibits remarkably better cycling stability and capacity retention as well as capacity utilization at high rates compared to bare lithium.

3860 mAh g −1 ), low redox potential (−3.04 V vs standard hydrogen electrode) and high capability to be coupled with high-voltage and/or high-capacity cathode materials. [1] However, the practical application of Li as an anode in rechargeable lithium batteries is still hindered by the uncontrollable growth of Li dendrites, low Coulombic efficiency (CE), and limited cycle life. [2] Numerous efforts have been made to address these issues. One of the strategies focuses on the design of suitable electrolytes by optimizing the concentration, [3] adding additives and fillers, [4] engineering highmodulus solid electrolytes and polymer electrolytes. [5] These advanced electrolytes are expected to have excellent electrochemical stability on the Li electrode and higher Young's modulus to resist the dendrite growth. [6] Further, developing stable host materials and nanostructured scaffolds to accommodate Li during the plating process has been employed to address the issues of large volume changes during lithium plating/stripping. [7] Recently, developing an artificial interfacial layer between the electrolyte and Li metal electrode has attracted tremendous attention in lithium metal batteries (LMBs). The interfacial layer can prevent side reactions, enable fast Li-ion diffusion, and suppress the Li dendrite growth for the efficient operation of Li metal anode. The side reactions and interfacial instability of Li metal lead to significant consumption of electrolyte. As a result, the resistance of the Li metal cell increases that leads to overpotential and ultimately short cell lifespan. Previous studies showed that various ceramics such as SiO 2 , TiO 2 , SnO 2 , and Al 2 O 3 are very promising interfacial layers to buffer the volumetric expansion of the anode. [8] Such ceramic layers are able to conduct Li + and block electron transport. [9] Lithiated multiwall carbon nanotubes and multilayered graphene with high mechanical rigidity have been reported as a controlled Li diffusion interface. [10] In addition, glass fibers, silica sandwiched between two separators, and silica@poly(methyl methacrylate) (SiO 2 @PMMA) nanosphere-modified Cu electrode has also been studied. [7c,11] These artificial layers improve wettability toward electrolyte, reduce the concentration of Li ions, and react with growing Li to suppress the dendrites. Organic/inorganic Lithium metal anodes are expected to drive practical applications that require high energy-density storage. However, the direct use of metallic lithium causes safety concerns, low rate capabilities, and poor cycling performance due to unstable solid electrolyte interphase (SEI) and undesired lithium dendrite growth. To address these issues, a radio frequency sputtered graphite-SiO 2 ultrathin bilayer on a Li metal chips is demonstrated, for the first time, as an effective SEI layer. This leads to a dendrite free uniform Li deposition to achieve a stable voltage profile and outstanding long hours plating/stripping compared to the bare Li. Compared to a bare Li anode, the graph...

Lithium metal is the ideal anode candidate but suffers from great challenges including poor thermodynamic stability in liquid organic electrolytes and dendrite nucleation/growth during the continuous plating/stripping process. To solve the difficulties listed above, here, a battery configuration combining a liquid lithium solution anode, a sulfide solid electrolyte, and an interfacial protection layer is proposed to prevent interfacial reaction between the two components. This configuration combines the advantages of liquid-lithium-solution anode (dissolve lithium to essentially prevent lithium nucleation) and sulfide solid electrolyte (highest room-temperature ionic conductivity among all solid electrolytes and ideal mechanical ductility for fully compact layer simply by cold pressing), so that a record-high current density (17.78 mA cm −2 ) and long cycle life (nearly 3000 h) are realized. At the same time, the solubility of lithium metal in the liquid Li anode and electrochemical properties of liquid Li anode are systematically studied to find the most suitable liquid Li anode concentration with the highest room-temperature conductivity (12.2 mS cm −1 ). This work provides a promising approach and battery configuration for achieving high-specificcapacity, high-energy/power-density and long-cycle-life secondary batteries.