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[Display omitted] • APS 3 monolayers have metallic electronic structure and a relatively low rate-limiting step. • APS 3 monolayers have low decomposition barriers of Li 2 S/Na 2 S. • Strain can reduces the rate-limiting step. 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 M 2 S n (n = 4, 6, 8), and the slow reaction kinetics. In this work, we perform first-principles calculations to find that the two-dimensional APS 3 (A = Cr, Co) monolayers are effective sulfur host materials for high-performance M–S batteries. The metallic electronic structures of APS 3 can accelerate electron transfer in reaction processes. The shuttle effect is inhibited by moderate binding strength between APS 3 and M 2 S n. Remarkably, APS 3 , as a bifunctional electrocatalyst, can greatly reduce the rate-limiting step of sulfur reduction reaction (SRR) and the decomposition barriers of Li 2 S/Na 2 S. We further explored the effect of strain engineering on the catalytic activity of APS 3 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. [ABSTRACT FROM AUTHOR]