A facile method for synthesizing CuS decorated Ti3C2 MXene with enhanced performance for asymmetric supercapacitors

Abstract

Two-dimensional (2D) layered materials are suitable electrode materials for electrochemical energy storage devices due to their distinctive properties. In this work, we report the preparation and electrochemical performance of 2D Ti₃C₂ decorated with CuS nanoparticles. CuS nanoparticles are hydrothermally distributed on the Ti₃C₂ sheets obtained by selectively etching Ti₃AlC₂, forming sandwich-like Ti₃C₂/CuS composites. Based on the standard three-electrode system, all the Ti₃C₂/CuS composite electrodes exhibit enhanced electrochemical performance with intense redox reactions in comparison with the Ti₃C₂ electrode. The optimum specific capacity of the Ti₃C₂/CuS composite electrode is as high as 169.5 C g⁻¹ at a current density of 1 A g⁻¹, which is about 5 times that of Ti₃C₂. The enhancement in specific capacity of the composite electrode is attributed to the synergistic effects of the excellent electronic conductivity of Ti₃C₂ and the superior electrochemical reaction activity of CuS. Moreover, a typical asymmetric supercapacitor device assembled with Ti₃C₂/CuS composites as the positive electrode and Ti₃C₂ MXene as the negative electrode exhibits a high energy density of 15.4 W h kg⁻¹ at a power density of 750.2 W kg⁻¹, and maintains 82.4% of the initial capacitance after 5000 cycles at a current density of 2 A g⁻¹. The strategy in this work can be extended to other 2D layered materials and systems, making full use of their potential.