Temperature driven pseudocapactive performance of WO₃/MXene nanocomposite for asymmetric aqueous supercapacitors

The WO₃ nanostructured materials are widely used as a pseudocapacitive charge storage electrodes. However it is restricted by poor cyclic stability. To overcome it, hybrid nanocomposites materialization of WO₃ with fascinating 2D MXene is an excellent strategy. Though both materials consumes acid based electrolytes and possesses layered structures, WO₃ protects MXene from self-restacking and/or aggregation of their adjacent layers owing to its strong van-der Waals interaction. Moreover layered structure of MXene offers synergistic action of various metal elements, fast diffusion of ions, increase the voltage window and cycle life. Herein we report hybrid nanocomposite of orthorhombic WO₃ nanoplates with 2D MXene nanoflakes prepared by a single-step hydrothermal method. The electrochemical investigations exhibits the specific capacitances of 21 F g⁻¹ (MXene), 112 F g⁻¹ (WO₃), and 290 F g⁻¹ (WO₃/MXene-20) at 0.5 A g⁻¹ in 1 M H₂SO₄ aqueous electrolyte. Furthermore temperature dependent investigation of a hybrid nanocomposite (WO₃/MXene-20) demonstrates consistent enhancement in the specific capacitance with the increasing temperature and a maximum capacitance of 376 F g⁻¹ at 0.5 A g⁻¹ is achieved at 50 °C. Eventually an asymmetric aqueous supercapacitor (AASC) fabricated using hybrid nanocomposite (WO₃/MXene-20) demonstrates an outstanding cyclic stability up to 20,000 cycles at 5 A g⁻¹ upholding 72 % capacitance retention and 73 % coulombic efficiency. The exceptional cyclic stability of the AASC configuration emphasizes the prospective of WO₃/MXene hybrid nanocomposites for durable energy storage applications.