In situ formed LiF-Li3N interface layer enables ultra-stable sulfide electrolyte-based all-solid-state lithium batteries

Abstract

Sulfide solid electrolytes are promising for high energy density and safety in all-solid-state batteries due to their high ionic conductivity and good mechanical properties. However, the application of sulfide solid electrolytes in all-solid-state batteries with lithium anode is restricted by the side reactions at lithium/electrolytes interfaces and the growth of lithium dendrite caused by nonuniform lithium deposition. Herein, a homogeneous LiF-Li3N composite protective layer is in situ formed via a manipulated reaction of pentafluorobenzamide with Li metal. The LiF-Li3N layer with both high interfacial energy and interfacial adhesion energy can synergistically suppress side reactions and inhibit the growth of lithium dendrite, achieving uniform deposition of lithium. The critical current densities of Li10GeP2S12 and Li6PS5Cl are increased to 3.25 and 1.25 mA cm−2 with Li@LiF-Li3N layer, which are almost triple and twice as those of Li-symmetric cells in the absence of protection layer, respectively. Moreover, the Li@LiF-Li3N/Li10GeP2S12/Li@LiF-Li3N cell can stably cycle for 9000 h at 0.1 mA cm−2 under 0.1 mA h cm−2, and Li@LiF-Li3N/Li6PS5Cl/Li@LiF-Li3N cell achieves stable Li plating/stripping for 8000 h at 0.1 mA cm−2 under 10 mA h cm−2. The improved dynamic stability of lithium plating/stripping in Li@LiF-Li3N/Li10GeP2S12 or Li6PS5Cl interfaces is proved by three-electrode cells. As a result, LiCoO2/electrolytes/Li@LiF-Li3N batteries with Li10GeP2S12 and Li6PS5Cl exhibit remarkable cycling stability of 500 cycles with capacity retentions of 93.5% and 89.2% at 1 C, respectively.