Optimizing the electrochemical performance of 3D networked high-entropy layered double hydroxide/MXene heterojunctions via band gap engineering for constructing high-energy-density supercapacitors

Layered double hydroxides (LDH) have shown great potential in the field of high-energy-density supercapacitors, but their poor electron transport capability and limited active sites have restricted their development. In this study, a NiCoMoMnZn-LDH/MXene-10 % (HE-LDH/M-10 %) composite material featuring a three-dimensional network heterogeneous structure was successfully synthesized through the integration of nano-etching and electrostatic self-assembly techniques. By adjusting the energy band structure of the high-entropy heterojunction, the composite material exhibited conductive properties close to those of metallic materials. Meanwhile, the interlaced layered structure provided additional space for charge storage. This electrode material demonstrates an exceptionally high specific capacitance (reaching 2412.7 F·g −1 at a current density of 0.5 A·g −1 ) and remarkable cycling stability (with a retention rate of 94.3 % after 8000 cycles), surpassing most high-entropy electrode materials reported to date. The hybrid supercapacitor constructed with this positive electrode can achieve a maximum energy density of 82.7 Wh·kg −1 , indicating significant application potential. Moreover, this study elucidates the electrochemical enhancement mechanism of high-entropy heterojunctions through comprehensive experimental investigations and density functional theory (DFT) calculations. This research proposes a novel concept for advancing high-energy-density supercapacitors.