Optimizing the p charge of S in p -block metal sulfides for sulfur reduction electrocatalysis

Understanding sulfur conversion chemistry is key to the development of sulfur-based high-energy-density batteries. However, unclear relationships between the electronic structure of the catalyst and its activity are the major problem. Here, we provide a direct correlation between the p electron gain of S in p -block metal sulfides and the apparent activation energies ( E a ) for the sulfur reduction reaction (SRR), in particular, Li 2 S n to Li 2 S conversion, which is the rate-determining step of the SRR. The maximum p charge occurs in bismuth sulfide and results in the lowest E a and a high SRR rate in the cathode. Li–S batteries with the Bi 2 S 3 catalyst work steadily at a high rate of 5.0C with a high-capacity retention of ~85% after 500 cycles. A high areal capacity of ~21.9 mAh cm −2 was obtained under a high sulfur loading of 17.6 mg cm −2 but a low electrolyte/sulfur ratio of 7.5 μl mg −1 .