Carbon nitride encapsulation of P-doped AlCoN nanocubes via dicyanamide nitridation for improved charge storage in solid-state supercapacitors

초록

Metal nitride-based electrodes show significant potential in energy storage applications owing to their robust mechanical properties, excellent conductivity, and enhanced redox activity; however, their practical deployment is limited by their poor electrochemical stability. In this work, phosphorus-doped AlCoN derived from Prussian Blue analogs (PBAs) was encapsulated within porous carbon nitride (PCN) nanosheets via combined co-precipitation and dicyanimide-assisted nitridation to afford a core–shell, cube-like architecture (P-AlCoN@PCN). The use of sodium hypophosphite as the phosphorus doping source enhanced the conductivity of the AlCoN nanocubes. Ultrafine CoN nanoparticles (∼7 nm), significantly smaller than those in pristine AlCoN (∼41 nm), were evenly distributed throughout the carbon matrix of the core, underscoring the pivotal role of PCN nanosheets in the formation of crystalline CoN. This architecture improves structural stability and promotes efficient charge transport and ion diffusion. Electrochemical testing using a three-electrode system revealed a maximum specific capacitance of 1531.2 F/g and outstanding cycle stability (98.5 % capacity maintained after 10,000 cycles). When integrated into an asymmetric supercapacitor with a ZnFeN@NG anode, the device achieved a remarkable energy density of 71.7 Wh/kg with an adjusted power density of 750 W/kg, and capacitance retention of 94.1 % after 10,000 cycles. These results highlight the utilization of MN-based core–shell systems in advancing high-performance, environmentally sustainable energy storage devices.

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