Flexible supercapacitor with manganese-based sulfides electrode for high electrochemical performance

A cost-effective and facile method for chemical synthesis of manganese-based sulfides (MS) and investigation of the structure, morphology, and electrochemical properties have been reported in this work. The MS electrode exhibits exceptional electrochemical performances including ultrahigh specific capacitance (8.2 F cm-2), excellent cycle life (88.6 % retention after 3500 cycles), and good rate capability (86.6 % retention at 50 mA cm-2). Furthermore, to solve the shortcomings of liquid electrolyte supercapacitors, including electrolyte leakage, corrosion, and environmental pollution, a solid-state supercapacitor assembled with MS positive electrode and camphor seed derived carbon (CSDC) negative electrode have been successfully fabricated (MS// CSDC), which shows a maximum specific capacitance about 351.9 mF cm-2 with capacitance retention about 87.6 % after 2500 cycles. Specifically, the energy density of 0.55 mWh cm-3 at a power density of 11.25 mW cm-3 can be achieved, demonstrating excellent supercapacitive behaviors of such as-fabricated device. Furthermore, the CV curves of such device prior to and following bending do not change significantly at 10 mV s-1, which indicates good mechanical flexibility and stability. Notably, the asymmetric MS//CSDC solid-state supercapacitors connected in series can quickly illume red LEDs, emerging their practical application prospects for such prepared flexible devices.