Heterogeneous bilayer as an artificial solid-electrolyte-interphase for dendrite free lithium deposition in lithium metal batteries

Lithium metal anodes (LMAs) are considered promising for driving high energy density battery applications, owing to their higher theoretical specific capacity, lower mass density and lower redox potential, compared to conventional graphite based anode. Despite attractive features, the direct use of LMA challenges safety concern, and poor life span of the battery due to the inherent problems of infinite volume expansion, hyperactive nature, unstable solid electrolyte interphase (SEI) and undesired lithium dendrite growth. To resolve these issues, radio frequency (R-F) sputtering of ultrathin bilayer of graphite and SiO2 as an effective SEI layer on top of LMA chip was illustrated. As a result, dendrite-free uniform Li deposition, stable voltage profile and outstanding Li plating/stripping was achieved compared to that of bare LMA. Electrical conductive graphite electrically connect the plated Li and bulk LMA, lowers the impedance, buffers the volume expansion during Li plating/stripping and reduces the chances of dead Li formation. The addition of SiO2 facilitates fast Li-ion diffusion and simultaneously stores Li by alloying mechanism. As a result, outstanding electrochemical battery performance was obtained using hetereogeneous bilayer deposited LMA.