Carbon-Doped NiCuMn Supercapacitor with Excellent Energy Storage and Rate Capability

Abstract

Supercapacitors have gained prominence as a cutting-edge energy storage technology. However, the performance of conventional transition metal oxide electrodes is hindered by their poor electrical conductivity, insufficient ion-accessible surface area, and complex synthesis processes. Herein, a firsthand demonstration of carbon doping in a crystalline NiCuMn trimetallic alloy, followed by dealloying in an oxygen-rich environment, is presented. This process produces a highly uniform, 3D flaky nanoporous microstructure with exceptional electrochemical energy storage capabilities. The synthesized electrode demonstrates a remarkable specific capacitance of 1835 F cm⁻³ at an ultrahigh current density of 10 A cm⁻³ along with an excellent rate capability of ≈62%. In contrast, the carbon-free NiCuMn alloy shows 900 F cm⁻³ capacitance with only 35% retention under similar test conditions. A symmetric supercapacitor showcases an impressive energy density of 120.4 Wh L⁻¹ at a power density of 850 W L⁻¹. It also exhibits remarkable rate capability of ≈50% and excellent cyclic stability, maintaining 96.5% of its capacity after 10000 cycles. The exceptional performance of the developed electrode is attributed to its carbon-doped unique hierarchical microstructure that ensures efficient and rapid charge transport due to large surface area and high electrical conductivity.