A facile electrosynthesis approach of Mn-Ni-Co ternary phosphides as binder-free active electrode materials for high-performance electrochemical supercapacitors

Despite the massive efforts to produce binary metallic phosphides as electrode materials for energy storage purposes, little attempts are devoted to design ternary metallic phosphides, which should perform better than their single and binary counterparts. In this work, we demonstrate the fabrication of 3D flower-like ternary metallic manganese-nickel-cobalt phosphides (MNCPs) with different metal proportions using electrodeposition followed by low-temperature PH3 plasma treatment. Besides the positive synergistic effect of combining the three transition metals, the intriguing architecture with 3D networks and porous nanosheets enhances the capacity performance by facilitating fast electrolyte transport and active sites accessibility for high specific capacity. The best performing electrode reaches an ultra-high capacity of 1690 C g(-1) (equivalent to 3380 F g(-1)) in the three-electrode system at a current density of 1 A g(-1). The device combines both MNCP electrode and a bio-derived microporous carbon sheets (MCS) electrode sustains 1.5 V with exceptional specific capacitance of 176.8 F g(-1) at 1 A g(-1). The MNCP//MCS device manifests outstanding specific energy of 55.2 Wh kg(-1) at a power density of 749.91 W kg(-1). Importantly, the device maintains a high capacitive retention of 96% upon cycling over 8,0 00 charge-discharge cycles at 10 A g(-1). This impressive electrochemical performance designates that ternary metallic NiCoMn phosphides are promising candidates for energy storage applications. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study demonstrates the fabrication of 3D flower-like ternary metallic manganese-nickel-cobalt phosphides (MNCPs) with superior electrochemical performance, achieving high specific capacity and excellent capacitive retention. Combining the MNCP electrode with bio-derived microporous carbon sheets (MCS) electrode results in exceptional specific capacitance and high specific energy in energy storage applications.