Interface Re-Engineering of Li10GeP2S12 Electrolyte and Lithium anode for All-Solid-State Lithium Batteries with Ultralong Cycle Life.

An ingenious interface re-engineering strategy was applied to in situ prepare a manipulated LiH2PO4 protective layer on the surface of Li anode for circumventing the intrinsic chemical stability issues of Li10GeP2S12 (LGPS) to Li metal, specifically the migration of mixed ionic-electronic reactants to the inner of LGPS, and the kinetically sluggish reactions in the interface. As consequence, the stability of LGPS with Li metal increased substantially and the cycling of symmetric Li/Li cell showed that the polarization voltage could keep relative stable for over 950 h at 0.1 mA cm-2 within ±0.05 V. The optimized ASSLiB of LiCoO2 (LCO)/LGPS/Li with interface-engineered structure was able to deliver long cycle life and high capacity, i.e., a reversible discharge capacity of 131.1 mAh g-1 at the initial cycle and 113.7 mAh g-1 at the 500th cycle under 0.1 C with a retention of 86.7%. In addition, the factors effected on the interphases formation of the LGPS/Li interface were analyzed, and the mechanism of the stability between LGPS and Li anode with protective layer was further investigated. Moreover, the probable causes of battery degradation were also explored. Above all, this work would give an alternative strategy for the modification of Li anode in high energy density solid-state lithium metal batteries.