Facile synthesis of MnO2@Ti3C2Tx composite electrodes for superior performance supercapacitor

Abstract

Supercapacitors are gaining traction in the energy storage sector due to their high power and energy density. MnO₂ is identified as a promising supercapacitors electrode material due to its reversible Faraday reaction and great theoretical specific capacitance. However, its practical performance is hindered by poor electrical conductivity and structural instability. By incorporating Ti₃C₂T_x, a 2D MXene material known for its high conductivity and functional groups, the electrochemical behavior of the MnO₂ composite is expected to be enhanced. This study introduces a novel method for synthesizing MnO₂@Ti₃C₂T_x self-assembled electrodes (1, 3, 6, 9-MnO₂@Ti₃C₂T_x composite electrodes) via a simple solution immersion technique at room temperature and ambient pressure. The state of manganese dioxide deposition can be influenced by varying the number of operations of the solution immersion technique. Among them, 6-MnO₂@Ti₃C₂T_x has the largest specific surface area and achieves the best specific capacitance of 324.1 F g⁻¹. When the current density is increased to 10 A g⁻¹, the specific capacitance retention of 6-MnO₂@Ti₃C₂T_x is 67.11 %. Furthermore, the 6-MnO₂@Ti₃C₂T_x//Ti₃C₂T_x asymmetric capacitor demonstrated a maximum energy density of 30.8 W h kg⁻¹ and a power density of 7493.3 W kg⁻¹, maintaining a capacitance retention rate of 95.98 % (from 74.6 to 71.6F g⁻¹) after 2000 charge-discharge cycles. This study presents an effective and scalable synthesis strategy for MnO₂ composite electrodes, highlighting their potential for future energy storage applications.