Supercapacitive Performances of Single-Phase Quaternary Metal Hydroxychlorides

Graphical A single-phase quaternary M 2 (OH) 3 Cl based composite is prepared, derived from a deep eutectic solvent annealing process, followed by exposure to air at ambient temperature. The quaternary M 2 (OH) 3 Cl composite exhibits an excellent supercapacitive performance, exceeding unary, binary, and ternary metal hydroxychlorides. This strategy offers new possibilities for improving the capacitive performance of metal hydroxychlorides. Metal hydroxychloride, as a new electrode material, shows an excellent electrochemical performance owing to the presence of abundant Cl − ions and hydroxyl groups. Herein, a single-phase quaternary M 2 (OH) 3 Cl based composite is constructed, for the first time, via a simple deep eutectic solvent annealing process, followed by the exposure to air at ambient temperature. Herein, this composite, denoted as M 2 (OH) 3 Cl-4/CoNi/N−C, is made up of ultrafine M 2 (OH) 3 Cl nanoparticles composed of Mn 2+ , Fe 2+ , Co 2+ and Ni 2+ , CoNi alloy nanoparticles and N-doped carbon with a degree of graphitization. M 2 (OH) 3 Cl-4/CoNi/N−C exhibits an excellent specific capacitance of 1576.6 F g −1 at 0.5 A g −1 , exceeding the unary, binary and ternary metal hydroxychlorides, which is attributed to the synergistic effect among the four metals in M 2 (OH) 3 Cl and the formation of CoNi alloy nanoparticles and carbon substrates. Our findings offer promise for creating unique functional materials via combining multiple components with distinctive properties.