Conformal phosphating hierarchical interface of CC/CoNiMn-P for hybrid supercapacitors with high rate stable cycling

Abstract

Transition metal phosphides (TMPs) have gained widespread applications in the field of electrochemical energy storage. However, controlled morphology and multi-site dynamic activation remain challenging. Herein, a thin-walled, hollow, and porous ternary Co-Ni-Mn metal phosphide was synthesized on carbon cloth (CC/CoNiMn-P) via a mixed-solvent-assisted etching method combined with gas-phase phosphidation, using Co-MOF and CoNiMn(OH)2 triangular nanosheet arrays as templates. The mild phosphating process maintained the hollow porous structure of the master plate. The DFT calculation further proved that the insertion of P improved the adsorption of the electrode to OH-, thus improving the conductivity and thermal stability. Combined with the synergistic effect of ternary metals, the electrode showed a high specific capacity 2247 F•g-1 at a current density of 1 A•g-1, and excellent rate performance (with 90.2% retention at 8 A•g⁻¹). When used in hybrid supercapacitors (HSCs), the CC/CoNiMn-P-500//AC HSC achieves a high energy density of 45.7 Wh•kg⁻¹ at a power density of 344.8 W•kg⁻¹, with a capacitance retention of 84.3% after 10,000 cycles. This work provides a novel approach for constructing electrode materials with well-defined hierarchical structures for supercapacitor and energy storage applications.