Monolayers APS3 (A = Cr, Co) as cathode hosts for lithium/sodium-sulfur batteries with enhanced electrochemical performance

Metal-sulfur batteries (M–S batteries, M = Li, Na), because of their high energy density and low cost, are expected to become the next-generation energy storage systems. However, their commercial applications are impeded by the poor conductivity of polysulfides, the "shuttle effect" of soluble M2Sn (n = 4, 6, 8), and the slow reaction kinetics. In this work, we perform first-principles calculations to find that the two-dimensional APS3 (A = Cr, Co) monolayers are effective sulfur host materials for high-performance M–S batteries. The metallic electronic structures of APS3 can accelerate electron transfer in reaction processes. The shuttle effect is inhibited by moderate binding strength between APS3 and M2Sn. Remarkably, APS3, as a bifunctional electrocatalyst, can greatly reduce the rate-limiting step of sulfur reduction reaction (SRR) and the decomposition barriers of Li2S/Na2S. We further explored the effect of strain engineering on the catalytic activity of APS3 for SRR and found that the battery performance can be regulated by varying the applied strains ranging from −2 % to 5 %. These findings provide a new direction for the design of highly efficient catalysts for M–S batteries.