Electrochemical Capacitor Performance of Nanotextured Carbon/Transition Metal Dichalcogenides Composites

Transition metal dichalcogenides (TMDs) are emerging low-dimensional materials with potential applications for electrochemical capacitors (EC). Here, physicochemical and electrochemical characterizations of carbon composites with two sulfides ReS₂ and FeS₂ are reported. To enhance conductivity, multiwalled carbon nanotubes (NTs) serve as a support for ReS₂ while 3D graphene-like network (3DG) is utilized for FeS₂ deposition. Unique structure of carbon/TMDs composites allows a faradaic contribution of sulfides to be exploited. Capacitance values, charge/discharge efficiency, capacitance retention, charge propagation, cyclabilty, and voltage limits of EC with carbon/sulfide composites in aqueous neutral solutions (Li₂ SO₄ , Na₂ SO₄ ) are analyzed. Special attention is devoted to energetic efficiency of capacitive charge/discharge processes. Structure-to-capacitance correlation for the composites with various TMDs loading is thoroughly emphasized. The more defected structure of layered NTs/ReS₂ composite is responsible for the lower capacitor voltage (0.8 V) owing to quicker electrolyte decomposition. Additionally, the catalytic effect of Re for hydrogen evolution reaction plays a crucial role in EC voltage restriction. Contrary, the operating voltage of capacitor based on 3DG/FeS₂ is able to be extended until 1.5 V in sodium sulfate electrolytic solution.