Improving poisoning resistance of electrocatalysts via alloying strategy for high-performance lithium-sulfur batteries

Abstract

Transition metals (TMs) are attractive electrocatalysts for lithium-sulfur (Li-S) batteries due to their strong adsorption of sulfur species based on Lewis acid-base interactions and high intrinsic conductivity. However, S8 molecule undergoes dissociation on their surfaces, resulting in sulfur-poisoned TMs with reduced catalytic sites. We propose here an alloying strategy which changes the S adsorption sites and the corresponding binding energies, enabling intact adsorption of S8 as evidenced by theoretical and experimental results. Such merit renders Co-Te alloy a superior catalyst which effectively expedites the sulfur redox reactions and suppresses the shuttle effect. Consequently, the cathode with Co-Te alloy catalyst delivers an impressive rate capability of 898 mAh g−1 at 2 C together with a low capacity decay of 0.03% per cycle over 1000 cycles. Even the sulfur mass loading is up to 5.4 mg cm−2, a stable capacity of 5.0 mAh cm−2 can be still maintained after 100 cycles. Our work deepens the mechanism understanding of Li-S catalysis and opens a new avenue toward the design of poisoning-resistant electrocatalysts.