Catalytic hosts with strong adsorption strength for long shelf-life lithium-sulfur batteries under lean electrolyte

Abstract

Low electrolyte/sulfur ratio (E/S) is an important factor in increasing the energy density of lithium-sulfur batteries (LSBs). Recently, the E/S has been widely lowered using catalytic hosts that can suppress “shuttle effect” during cycling by relying on a limited adsorption area. However, the shelf-lives of these cathodes have not yet received attention. Herein, we show that the self-discharge of sulfur cathodes based on frequently-used catalytic hosts is serious under low E/S because the “shuttle effect” during storage process caused by polysulfides (PSs) disproportionation cannot be suppressed using a limited adsorption area. We further prove that the adsorption strength toward PSs, which is unfortunately weak in commonly-used catalytic hosts, is critical for effectively hindering the disproportionation of the PSs. Subsequently, to verify this conclusion, we prepare a sulfur-doped titanium nitride (S-TiN) catalytic array host. As the adsorption strength and catalytic activity of TiN can be improved by S doping simultaneously, the constructed S/S-TiN cathodes under a low E/S (6.5 µL·mg−1) exhibit better shelf-life and cycle-stability than those of S/TiN cathodes. Our work suggests that enhancing the adsorption strength of catalytic hosts, while maintaining their function to reduce E/S, is crucial for practical LSBs.