Vulcanization Conditions of Bimetallic Sulfides Under Different Sulfur Sources for Supercapacitors: A Review

Transition metal sulfides are considered to be potential electrodes for supercapacitors because of their excellent stability and large capacitance. Single metal sulfides, despite of tremendous efforts devoted to the morphological design, their intrinsic weaknesses such as low surface area and inactive ion transfer hinder their practical application. Recently, bimetallic sulfides have gained a lot of attention due to their considerable theoretical capacities, good reversible redox ability, and low cost. Bimetallic sulfides are usually synthesized via anion exchange method, in which oxygen-containing anion in the precursor was replaced by S 2− in the sulfur source. As for the sulfur source, it can be divided into organic sulfur sources and inorganic sulfur sources and their vulcanization mechanism together with vulcanization condition are totally different, which results in bimetallic sulfides with diverse morphology, structure, specific surface area, conductivity and chemical composition. In this review, the recent progress of bimetallic sulfide electrodes prepared with various sulfide sources under different vulcanization conditions such as vulcanization temperature, vulcanization time, vulcanization concentration, is summarized and analyzed. Besides, new insights to improve the specific capacitance of bimetallic sulfides and extend the application of bimetallic sulfides in commercial energy storage device are discussed. Graphical Abstract