Rotational chemical bath deposited flexible MnO₂/MXene thin film as an electrode for all solid state asymmetric supercapacitor

Abstract MXenes are stealing the spotlight due to their metallic conductivity and hydrophilicity; however, the restacking of 2D layers in MXene hampers the electrochemical performance. On the contrary, MnO₂ is considered a promising electrode material for its variable oxidation states, but its weak conductivity limits practical applications. Taking the complementary properties, studies on the in-situ synthesis of MnO₂@MXene by chemical bath deposition (CBD) for energy-related (supercapacitor) applications have not yet been explored. Thus, exploring the opportunity for the first time to examine the performance of MnO₂/Ti₃C₂T _x supercapacitor applications by directly growing nano architectures on a flexible stainless steel mesh substrate utilising a binder-free synthesis approach was of our interest. With this motivation, the present investigation deals with a MnO₂/Ti₃C₂T _x (MnO₂/MXene) composite thin film designated as an MMC electrode deposited on the stainless steel mesh (300 mesh size) via an in-situ modified CBD method called rotational CBD (R-CBD). The synthesised MMC exhibits an excellent specific capacitance of 1130 F g⁻¹ when compared to MnO₂ (628.3 F g⁻¹) and MXene (32.5 F g⁻¹) at a current density of 1 mA cm⁻². A flexible MnO₂/MXene//MXene-based asymmetric supercapacitor device exhibited specific capacitance of 43.7 F g⁻¹ at 2 mA cm⁻² current density, maximum energy density (6.06 Wh kg⁻¹), and power density (0.6 kW kg⁻¹).