Synthesis of MnS microfibers for high performance flexible supercapacitors

Highlights: • Microfiber textured cubic MnS thin films are prepared from acidic solution. • The highest specific capacitance (C_s) of 747 Fg^-1 is obtained for bare MnS in 1M KOH electrolyte. • Two MnS symmetric supercapacitor devices in series demonstrated intense red LED illumination. Cubic MnS thin films are prepared at 358 K bath temperature using chemical bath deposition (CBD) method. MnS phase of manganese sulfide is identified with X-ray diffraction (XRD) and X-ray photoemission spectroscopy analyses. Interconnected porous microfibers like surface texture of MnS thin film is evaluated through field-emission scanning electron microscopy (FE-SEM). Specific surface area of 120.42 m² g⁻¹ is measured with Brunauer-Emmett-Teller (BET) technique. The highest specific capacitance (C_s) of 747 F g⁻¹ is obtained using galvanostatic charge discharge (GCD) technique at 1 mA cm⁻² current rate. Excellent 85% capacity retention is obtained after 2 000 CV cycling at 100 mV s⁻¹ scan rate. All solid state flexible (ASSF) symmetric supercapacitor devices based on microfiber-MnS thin films are prepared using cost effective stainless steel substrate and PVA-KOH gel electrolyte and practical application is demonstrated by illumination of red LED.