R-F Sputtered Ultrathin Organic/Inorganic Bilayer for Dendrite Free Li Deposition

Abstract

Lithium metal anodes have attracted great attention due to its high theoretical capacity and low redox potential. However, the notorious reactivity, uncontrolled solid electrolyte interphase (SEI) and undesired results in low battery performance and risk for safety concern. To resolve these problems, radio frequency (R-F) sputtered ultrathin bilayer of graphite and SiO2 ultrathin bilayer on a Li metal was demonstrated, for the first time, as an effective SEI layer. The graphite-SiO2 bilayer modified Li anode showed an improved capacity retention of 98.57% for lithium nickel cobalt manganese oxide cathode (NMC111) and 96.78% for lithium titanate (LTO), compared to bare Li anodes at 82.73% (NMC111) and 92.31% (LTO), respectively. Higher capacity, longer cycling stability and lower voltage hysteresis were obtained with the use of the graphite and SiO2 modified Li anode. Graphite acts as an electrical bridge between the plated Li and Li electrode, which lowers the impedance and buffers the volume expansion during Li plating/stripping. The addition of an ultrathin SiO2 layer facilitates Li diffusion and lithiation/delithiation, provides higher electrolyte affinity, higher chemical stability, and higher Young’s modulus to suppress the Li dendrite growth. This novel technique can open further pathways towards practical realization of use of lithium metal battery (LMB) in high energy density battery technologies such as Li-S and Li-air battery.