Cost-Effective and High Ionic Conductivity Sulfide Solid Electrolyte Li7.3P2.9S10.75X0.3 (X = F, Cl, Br, and I) for All-Solid-State Lithium Batteries

Sulfide solid electrolytes (SSEs) have some huge advantages in high room-temperature conductivity, good thermal stability, low interfacial resistance, etc. They are one of the ideal solid electrolytes for developing high energy density and high safety for all-solid-state lithium batteries (ASSLBs). However, the preparation of SSEs requires expensive Li2S as the raw material, whose high cost limits its practical application. Herein, a cost-effective SSE Li7.3P2.9S10.75X0.3 (X = F, Cl, Br, and I) was designed and prepared by using low-cost lithium and sulfur instead of expensive Li2S. Significantly, the cost of SSEs was reduced from $169.72 to $28.13 kg–1 based on replacing the Li2S strategy. Moreover, the prepared Li7.3P2.9S10.75X0.3 (X = F, Cl, Br, and I) solid electrolytes have a high ionic conductivity of 1.86–2.73 mS cm–1 at room temperature and a high voltage window of 5 V. On this basis, we assembled the all-solid-state lithium battery TiS2/Li7.3P2.9S10.75I0.3/Li–In, which presented a high initial discharge capacity of 219 mA h g–1 at room temperature and satisfactory cycle stability with a capacity retention of 86.7% after 100 cycles at 0.50 mA cm–2. This work provides an effective strategy for reducing the cost of SSEs, advancing the practical process of ASSLBs.