Abstract
All-solid-state lithium-sulfur batteries (ASSLSBs) promise high theoretical energy density and inherent safety, but their full capacity delivery is seriously hindered by incomplete sulfur conversion. Here, we propose to exploit deep conversion of S(8) to Li(2)S via intermediate Li(2)S(2) by using tandem catalysis for high-capacity ASSLSBs, which we demonstrate by cobalt single-atom catalysts anchored on a conductive MXene substrate. In contrast to commonly believed one-step S(8) reduction to Li(2)S in ASSLSBs, our results show that tandem catalysis achieves stepwise S(8) reduction to Li(2)S via Li(2)S(2), during which atomically dispersed Co sites break S-S bonds and the polar MXene surface facilitates Li(+) diffusion, significantly reducing the sulfur conversion energy barriers. Consequently, the Co@MX-based ASSLSB reserves a high capacity of 1329 mAh g(S) (-1) after 2000 cycles at 2.8 mA cm(-2) at room temperature. This work demonstrates the promise of tandem catalysis for tailoring an all-solid-state sulfur conversion path and exploiting deep sulfur conversion capacity for high-performance ASSLSBs.