“…In the era of the 21st century, the world is witnessing an extensive development of novel electronic and optoelectronic devices, which entirely appeal to reliable power sources that combine higher energy density and long-term durability. , Thus, electronic devices put forward new challenges to the energy storage devices and technologies, where supercapacitors (SCs) have gained much attention as next-generation power storage sources mainly because of their safe operation, fast charge–discharge, and higher power density and longer cycle life than conventional batteries and fuel cells. − However, the main challenges lie in the development of flexible, high-energy-density, light-weight, heat-resistant SC devices. , From this standpoint, several scientific reports have been developed to construct electrodes with transition-metal oxides, hydroxides, selenides, sulfides, chalcogenides, nitrides, phosphides, etc. − In general, these are commonly known to be high-capacitive materials compared to classic electrical double-layer capacitors (EDLCs) possessing C-containing electrodes. , Among them, transition-metal phosphides (TMPs) have attracted wide interest because of their abundant electron orbitals, high electrical conductivity, metalloid properties, partial oxidation state of the metal center, and decent binding of oxide intermediates through feeble surface phosphate formation, which cumulatively help to boost the capacitive performance. − In this aspect, Ni- and Co-based binary metal phosphide (NiCoP) has attracted attention as an electrode material for energy storage because of its accessible free electrons for electrical conduction as well as exposed high density of surface metal atoms that impart energetically favorable active centers. − In addition, it shows high redox kinetic behavior and the synergistic effect of both Co and Ni in bimetallic phosphides improved ionic conduction compared to their monometallic counterpart. , …”