MXene@Cu2-xSe heteroarchitectures with synergistic redox-active sites for advanced asymmetric supercapacitors

Abstract

A novel MXene@Cu_2-xSe hybrid electrode has been successfully synthesized through a facile in situ selenization strategy. The two-dimensional layered architecture and abundant surface terminations of MXene provide favorable pathways for efficient ion diffusion and charge storage, while the incorporation of Cu_2-xSe nanoparticles significantly enhances the composite’s electroactive surface area and pseudocapacitive contributions. Systematic electrochemical characterization reveals that the MXene@Cu_2-xSe composite demonstrates a high specific capacitance of 384.0 F g⁻¹ at 1 A g⁻¹ in a three-electrode configuration. An asymmetric supercapacitor device was assembled using MXene@Cu_2-xSe as the positive electrode and activated carbon as the negative electrode, achieving a remarkable energy density of 71.1 Wh kg⁻¹ at a power density of 800 W kg⁻¹. Furthermore, the device exhibits outstanding cycling stability with 76.2 % capacitance retention after 8,000 charge–discharge cycles, demonstrating its potential for practical energy storage applications.