Performance-limiting factors of graphite in sulfide-based all-solid-state lithium-ion batteries

A suite of bulk and surface analytical techniques was applied to shed light on the factors limiting fast cycling composite graphite electrodes in all-solid-state cells based sulfide electrolytes 0.75Li2S-0.25P2S5 (LPS) 0.3LiI-0.7(0.75Li2S-0.25P2S5). Cracks poor percolation ionic conducting particles were identified by both scanning electron microscopy X-ray tomography slow kinetics during lithiation (limiting practical specific charge at rates >C/10, geometrical current densities >120 ?A cm?2) monitored operando diffraction supported Raman microscopy. Operando photoelectron spectroscopy absorption detected formation Li2S LixP interface between LPS graphite, compounds increasing interfacial resistance. Despite kinetic limitations, excellent long-term performance is demonstrated C/20 rate (at density about 60 cm?2), revealing self-passivation processes sulfide/graphite which stabilizes after approximately 200 full cycles.