Regulating the anion disorder and synthesizing the low-cost and high-performance Li6−xPS5−xCl1+x solid electrolytes

Abstract

Sulfide solid electrolytes have attracted wide attention due to their high ionic conductivity. Li6PS5Cl is one of the most promising electrolytes for all-solid-state lithium batteries with high-energy-density. It is reported that the disordered arrangement of Cl- in the aragonite structure has a significant effect on the conductivity of Li6PS5Cl. In this work, the disorder of anion sites is modestly regulated by adjusting the ratio of S and Cl in Li6−xPS5−xCl1+x electrolyte. In addition, to verify the commonality of this strategy, Li5.6PS4.6Cl1.4 is prepared using self-made Li2S, and similar results are obtained. On this basis, the density of Li5.6PS4.6Cl1.4 electrolyte sheet is improved by hot-pressing, which can successfully inhibit the growth of lithium dendrites. As expected, the ionic conductivity of the sulfide electrolyte and the electrochemical performance of the ASSLBs are greatly improved. A highest ionic conductivity of 8.2 × 10−3 S cm−1 of Li5.6PS4.6Cl1.4 is obtained at room temperature. A high capacity retention of 99.99 % is maintained for NCM811 @Li2O//Li5.6PS4.6Cl1.4//Li-In system after 400 cycles at 1 C with ultra-high cathode loading of 35.6 mg cm−2. Besides, the cost of sulfide electrolytes can be reduced as the decreased usage of Li2S. This work proposes a novel synthesis method of low-cost and high-performance Li6−xPS5−xCl1+x electrolytes.