Microwave construction of the 3D porous interconnected structure of NiCoCr medium-entropy alloy with ultra-high specific capacity for supercapacitors and electrocatalysis

Abstract

The effective design of bifunctional electrodes with unique morphology and remarkable electrochemical properties for energy conversion and storage devices is a promising but challenging endeavor. Herein, self-supporting NiCoCr medium-entropy alloy (MEA) with a hierarchical porous network structure was in situ synthesized on nickel foam (NiCoCr/NF) by a simple and rapid microwave route. The optimal NiCoCr/NF presented an ultra-high specific capacity of 3011.8 C g−1 (1 A g−1) and outstanding charge/discharge sustainability (83.4% retention at 10 A g−1 over 50,000 cycles) due to its multi-component synergistic effect and hierarchical porous structure. Meanwhile, subtle lattice distortions and electron density redistribution in the NiCoCr MEA tuned electronic structures, resulting in a low overpotential and Tafel slope. Aqueous and solid-state asymmetric supercapacitors were fabricated by using NiCoCr/NF as a cathode and Bi/NF as an anode. The aqueous supercapacitor displayed an exceptional energy density of 314.4 Wh kg−1 at a power density of 800 W kg−1 with 81.8% retention at 10 A g−1 over 20,000 cycles. This study provides a new strategy for the efficient synthesis of electrode materials with interconnected network structures and paves the way for the broader application based on medium-entropy and high-entropy materials as promising candidates for future energy storage devices.