Optimized electrosynthesis approach of Manganese-Nickel- Cobalt chalcogenide nanosheet arrays as binder-free battery materials for asymmetric electrochemical supercapacitors

Developing innovative energy storage platforms with long-lasting stability and high energy and power densities is a substantial endeavor that is urgently needed. To this end, supercapacitors are very promising candidates for such needs. However, supercapacitors still provide energy density that is below the required threshold for long-term applications mainly due to the lack to identify the optimum materials. Transition metal sulfides are a class of materials that can provide high energy density using different current collectors. However, most of the currently used current collectors are rigid, hindering their use in flexible supercapacitor devices. Herein, we report on one-pot electrodeposition of Mn-Ni-Co-S binder-free nanosheets on carbon cloth as a flexible substrate as confirmed via FESEM, XPS, and EDS analyses. The electrochemical characterization revealed that the electrodes exhibited a unique specific capacity of 2451 C g−1 (3771 F g−1) at 1 A/g with excellent stability over a wide range of current densities. The Ni-Mn-Co-S/CC was used in an asymmetric device as the positive electrode with a graphene hydrogel negative electrode providing power density and energy density at 1.0 A/g of 800 W/Kg and 49.55 Wh/Kg, respectively. The constructed device showed 100% Columbic efficiency with 86.5% capacitance retention after 12,000 cycles.