Preparation of CuMn₂O₄/Ti₃C₂ MXene composite electrodes for supercapacitors with high energy density and study on their charge transfer kinetics

In this study, we present a novel electrode material that combines Ti₃C₂ MXene and high-capacity CuMn₂O₄ to increase the energy density of supercapacitors, which are a popular choice for energy storage due to their high-performance potential. The electrode material was synthesized using the hydrothermal method with varying deposition times (3 h, 6 h and 9 h), and the resulting composite materials were characterized using advanced analytical techniques. The CuMn₂O₄/MXene composite electrode synthesized at 3h exhibited exceptional performance, with a specific capacitance of 628 mF/cm² at 4 mA/cm², due to the enhanced electrical conductivity and charge storage properties of CuMn₂O₄ and MXene sheets. We also uncovered an intricate charge transfer mechanism and storage kinetics of CuMn₂O₄/MXene composite on a nickel foam electrode, revealing a diffusion-controlled energy storage mechanism with fast mass transportation. To demonstrate practicality, we constructed an asymmetric coin cell supercapacitor device using CuMn₂O₄/MXene composite synthesized at 3h and activated carbon as the positive and negative electrodes, respectively. The device showed a specific capacitance of 496 mF/cm² at 6 mA/cm² with cyclic stability of 80% for up to 10,000 cycles, and a power density of 1.5 mW/cm² at a higher energy density of 0.073 mWh/cm². Our results demonstrate the potential to significantly advance the development of high-performance supercapacitors by combining Ti₃C₂ MXene and high-capacity oxides, refining the synthesis process, and exploring innovative electrode architectures.