A novel CoS/Ti3C2Tx MXene conductive filler effectively improves the pseudocapacitive performance of conductive hydrogel electrode materials for all-solid-state supercapacitors

It is currently an essential research direction to develop a low-cost, cost-effective, and environmentally friendly high-performance flexible electrode material. The electrode materials prepared from Ti3C2Tx MXene based hydrogels showed favorable physical and chemical properties (e.g., extreme flexibility, excellent mechanical strength, and electrical conductivity), and CoS (cobaltous sulfide) nanoparticles were grown by in-situ hydrothermal growth on the "accordion-like" Ti3C2Tx MXene surfaces, which were then synthesised into PCCT (PAA/chitosan/CoS/Ti3C2Tx) conductive hydrogels with physical crosslinked networks in a two-step process. This 3D porous structure containing highly conductive materials can provide suitable geometrical space and electronic structure, which can help to suppress the accumulation of active material at high mass loading and improve the specific capacitance of the electrode material. With a current density of 4 mA/g, the specific capacitance of the PCCT conductive hydrogel electrode was 3.6F/g. At a current density of 10 mA/g, the cycling stability was still 80 % after 2000 cycles. The elongation at break of PCCT conductive hydrogel wass about 349 %. After 48 h of healing at room temperature, the self-healing efficiency can reach 66.88 %. A foundation has been laid for obtaining flexible all-solid-state supercapacitors with stable structures and excellent electrochemical properties.