High mass loading of h-WO3 and α-MnO2 on flexible carbon cloth for high-energy aqueous asymmetric supercapacitor

Highlights: • Binder-less approach was used to prepare high-mass loaded h-WO₃ and α-MnO₂ on flexible CC. • The all-pseudocapacitive α-MnO₂//h-WO₃ asymmetric supercapacitor device showed a high energy density of 0.095 mWh/cm³. • The device exhibited excellent rate capability and long-term cycling stability over 7500 cycles without decrement. -- Abstract: The increasing interest in portable and consumable electronics demands efficient and low-cost energy storage devices with excellent energy storing capacity. From this point, a high mass loading of the active electrode material on three-dimensional current collectors is favorable for obtaining a higher energy storing capacity for the corresponding device. The present study demonstrates an ideal example of high-performance aqueous asymmetric supercapacitors (SCs) using α-MnO₂ nanowires as the positive electrode and h-WO₃ nanorods as the negative electrode, respectively. Initially, one-dimensional (1D) nanostructures composed of α-MnO₂ and h-WO₃ are prepared on carbon cloth by a conventional hydrothermal method. The prepared α-MnO₂ and h-WO₃ with a high mass loading of 4.9 mg/cm² and 5.8 mg/cm², respectively, show excellent electrochemical features in aqueous Na₂SO₄ electrolyte in the positive and negative potential regions. A high-performance asymmetric SC is developed with uniquely engineered electrodes, which exhibits the excellent electrochemical performance in an extended potential window of 1.4 V and with excellent cycling stability of ∼135% after 7500 cycles with a volumetric capacitance of 350 mF/cm³ and energy density of 0.095 mWh/cm³. This authentic scheme may offer new opportunities for developing asymmetric arrangements for energy storage devices in various portable electronic systems with a high mass loading.