Interfacial Stabilization by Prelithiated Trithiocyanuric Acid as an Organic Additive in Sulfide-Based All-Solid-State Lithium Metal Batteries

Sulfide-based all-solid-state battery (ASSB) with a lithium metal anode (LMA) is a promising candidate to surpass conventional Li-ion batteries owing to their inherent safety against fire hazards and potential to achieve a higher energy density. However, the narrow electrochemical stability window and chemical reactivity of the sulfide solid electrolyte towards the LMA results in interfacial degradation and poor electrochemical performance. In this direction, we introduce an organic additive approach, that is the mixing of prelithiated trithiocyanuric acid, Li3TCA, with Li6PS5Cl, to establish a stable interface while preserving high ionic conductivity. Including 2.5 wt % Li3TCA alleviates the decomposition of the electrolyte on the lithium metal interface, decreasing the Li2S content in the solid-electrolyte interface (SEI) thus forming a more stable interface. In Li|Li symmetric cells, this strategy enables a rise in the critical current density from 1.0 to 1.9 mA cm-2 and stable cycling for over 750 hours at a high current density of 1.0 mA cm-2. This approach also enables Li|NbO-NCM811 full cell to operate more than 500 cycles at 0.3 C. Facile bulk functionalization of Li6PS5Cl with prelithiated trithiocyanuric acid is introduced as an organic additive strategy to stabilize the interfaces in sulfide-based all-solid-state lithium metal batteries. This approach improves electrochemical performance markedly due to the formation of a highly stable Li2S deficient and Li3P-rich interface with Li metal anode. image