Interface engineering of sulfide electrolytes for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLIBs) employing sulfide solid electrolyte hold high promise to replace traditional liquid-electrolyte LIBs due to their high safety and energy density. However, Li dendritic growth in sulfide electrolyte limits the realization of the high energy of ASSLIBs. In this work, we use LiF (or LiI) layer at the interface between Li and sulfide electrolyte and penetrated HFE (or I solution) inside of sulfide electrolyte to suppress the Li dendrite growth. Due to the higher interface energy of LiF/Li than that of LiI/Li, LiF interlayer show much higher capability than LiI in suppressing the Li dendrite. Even if the Li dendrite breaks through LiF (or LiI) interlayer, the Li dendrites will be consumed by coated/penetrated HEF (or I) forming LiF (or LiI) thus preventing Li dendrite growth. A LiNbO3 @LiCoO2/Li7P3S11/Li ASSLIB employing HFE coated/infiltrated Li7P3S11 glass-ceramic as electrolyte, and LiF coated Li metal as anode shows a high reversible discharge capacity of 118.9 mAh g−1 at 0.1 mA cm−2 and retains 96.8 mAh g−1 after 100 cycles. The designed solid electrolyte interphase between Li and solid electrolyte that has a high interface energy to Li provides new opportunity to commercialize the Li metal batteries. We demonstrate that a uniform the LiF (or LiI) interfacial layer at Li/Li7P3S11 interface and infiltration of HFE (or I solution) into sulfide electrolyte can suppress the Li dendrite growth. Due to the modification, the assembled Li@LiF/Li7P3S11/LiF@Li symmetrical cell can stably plating/stripping at 0.5 mA cm−2 and 0.1 mAh cm−2 at 25 °C for over 200 cycles. Coupled with the LNO-LCO cathode, the all-solid-state Li@LiF/Li7P3S11/LNO@LCO full cell exhibits a high initial reversible capacity of 118.9 mAh g−1 with excellent cycling stability and high rate performances at room temperature. [Display omitted] •Rational coating of LiF (or LiI) on Li enables stable interface.•Infiltrating HFE (or I) into electrolytes suppresses the growth of Li dendrites.•High interface energy of LiF/Li promotes a uniform Li deposition.•High electrochemical performance was achieved for the cell with Li@LiF and HFE.