Work

Stable Liquid-Sulfur Generation on Transition-Metal Dichalcogenides toward Low-Temperature Lithium–Sulfur Batteries

Year: 2022

Type: article

Abstract: The electrochemical formation of liquid sulfur at room temperature on the basal plane of MoS 2 has attracted much attention due to the high areal capacity and rapid kinetics of lithium–liquid sulfur chemistry. However, the liquid sulfur is converted to the solid phase once it contacts the solid sulfur crystals generated from the edge of MoS 2 . Thus, stable liquid sulfur cannot be formed on the entire MoS 2 surface. Herein, we report entire liquid sulfur generation on hydrogen-annealed MoS 2 (H 2 -MoS 2 ), even under harsh conditions of large overpotentials and low working temperatures. The origins of the solely liquid sulfur formation are revealed to be the weakened interactions between H 2 -MoS 2 and sulfur molecules and the decreased electrical polarization on the edges of the H 2 -MoS 2 . Progressive nucleation and droplet-merging growth behaviors are observed during the sulfur formation on H 2 -MoS 2, signifying high areal capacities by releasing active H 2 -MoS 2 surfaces. To demonstrate the universality of this strategy, other transition-metal dichalcogenides (TMDs) annealed in hydrogen also exhibit similar sulfur growth behaviors. Furthermore, the H 2 annealing treatment can induce sulfur vacancies on the basal plane and partial oxidation on the edge of TMDs, which facilitates liquid sulfur formation. Finally, liquid sulfur can be generated on H 2 -MoS 2 flakes at an ultralow temperature of −50 °C, which provides a possible development of low-temperature lithium–sulfur batteries. This work demonstrates the potential of a pure liquid sulfur–lithium electrochemical system using functionalized two-dimensional materials.

Source: ACS Nano

DOI: 10.1021/acsnano.2c04769