A scalable sulfuration of WS₂ to improve cyclability and capability of lithium-ion batteries

Two-dimensional transition-metal dichalcogenides (WS₂ and SnS₂) have recently joined the family of energy storage materials (for lithium-ion batteries and supercapacitors) as a result of their favorable ion intercalation. So far, challenges in the synthesis of phase-pure WS₂, restacking between WS₂ nanosheets, low electronic conductivity, and the brittle nature of WS₂, severely limit its use Li-ion battery application. Herein, we develop a facile low temperature solution sulfuration process to improve battery performance dramatically. The sulfuration process is demonstrated to be effective in converting WO₃ impurities to WS₂, and in repairing the sulfur vacancies, to improve cyclability and rate capability. Lithium-ion battery measurements demonstrate that the stable capacity of the WS₂ anode could be enhanced by 48.4% via sulfuration reprocessing, i.e., from 381.7 to 566.8 mAh/g at a relatively high current density of 0.8 A/g after 50 cycles. We further show that the sulfuration process can be readily extended to other dichalcogenides, and may provide a class of versatile electrode materials for lithium-ion batteries with improved electrochemical characteristics.