Optimization of cobalt-manganese binary sulfide for high performance supercapattery devices

Abstract Hybrid supercapacitors have attained incredible attention for their versatile worth in energy storage applications, still desire to enhance the specific energy and power limit by employing an electrode material with flashing electrochemical performance. Transition metal sulfides for their high electrochemical activities and better conductivity are promising electrode materials. Here we report the performance optimization of binary metal sulfide synthesized by the sonochemical approach. Initially, cobalt and manganese sulfides were prepared, then the composition of cobalt and manganese was varied in binary metal sulfides. The phase structure, elemental analysis, and morphological aspects were studied via X-ray, diffraction (XRD), energy dispersive X-Ray spectroscopy (EDX), and scanning electron microscopy (SEM). The electrochemical test in three electrode cell configuration reveals that Co0.5Mn0.5S exhibited prime electrochemical performance compared to all other compositions. A specific capacity of 713.13 C/g at 3 mV/s and 536.0 C/g (specific capacitance of 893.3 F/g) at 1.0 A/g was obtained from Co0.5Mn0.5S. This electrode material was further utilized in an asymmetric (supercapattery) device along with activated carbon. The electrochemical analysis of the supercapattery device was carried out in two electrode assembly. The fabricated device has achieved exceptional specific energy of 61.34 Wh/kg at a specific power of 850 W/kg and retains specific energy of 9.92 Wh/kg while providing remarkable specific power of 8500 W/kg. In addition, the device also demonstrated outstanding capacity retention of 90.19% after 2000 consecutive GCD cycles at 10 A/g. Moreover, the device performance was further scrutinized by a simulation approach in terms of capacitive and diffusive contributions. These impressive results demonstrate that the Co0.5Mn0.5S is a favorable electrode material for high performance supercapattery applications.