Binary solvent-assisted solvothermal approach for the synthesis of α/γ-MnS for supercapacitor applications

Manganese sulfide (MnS) has received attention as an outstanding electrode material for supercapacitors, demonstrating high theoretical capacitance, environmental safety, lower production costs, and superior conductivity. Among its phases, α-MnS is the best phase for supercapacitors because of its cubic structure, which remains stable during long-term use and withstands degradation effectively. Moreover, the addition of minimal hexagonal γ-MnS phase functions as an ion transfer pathway, accelerating the overall conductivity. The combination of α-MnS for stability and γ-MnS for ion transfer produces an electrode with improved electrochemical performance. To achieve MnS nanoparticles with a dominant α-phase and minor γ-phase, this study employed the binary solvent-assisted solvothermal method and optimized it at different temperatures and durations. The optimized MnS electrode displayed a higher specific capacitance of 237 F/g at a current density of 0.5 A/g and 87% capacitive retention over 500 cycles. The MnS symmetric supercapacitor (SSC) achieved 28 F/g at 0.5 A/g with an excellent capacity retention rate of 117%. The LED powered by four symmetric cells for 8 min indicates the practical application of supercapacitors in real-world applications.