Development and characterization of high-performance 1.6 V asymmetric supercapacitor using Mn ₂ O ₃ //rGO-TiO ₂ in aqueous electrolyte

Abstract A supercapacitor cell in organic electrolyte with carbon-based electrodes has been commercialized. However, there are a few supercapacitor cell systems on the market that use aqueous electrolytes. In the current study, a high-performance supercapacitor cell is constructed in an asymmetric configuration using hydrothermally manufactured Mn 2 O 3 microspheres as a positive electrode and hydrothermally synthesized rGO-TiO 2 as a negative electrode in an aqueous electrolyte. The device provides a wide operational voltage window of 0 to 1.6 V, significantly surpassing the voltage ranges typically seen in aqueous-based supercapacitors. It achieves exceptional electrochemical performance metrics, including a high specific capacitance of 321 F g −1 , an energy density of 114 W h kg −1 and a power density of 571 W kg −1 . These results show a significant improvement over symmetric designs like Mn 2 O 3 //Mn 2 O 3 (energy density: 37 W h kg −1 at 357 W kg −1 ) and rGO-TiO 2 //rGO-TiO 2 (energy density: 18 W h kg −1 at 214 W kg −1 ). The asymmetric cell has an energy density of 71 W h kg −1 and an ultra-high power density of 57,142 W kg −1 , making it suitable for rapid energy delivery applications. Additionally, excellent stability during cycling is observed at a higher discharge current density of 10.71 A g −1 , sustaining more than 82% of the initial capacitance after 10,000 charge–discharge cycles. The adoption of a CR2032 coin cell type emphasizes the practicality of this high-voltage aqueous supercapacitor device for next-generation energy management and storage applications.