Aqueous MBene-Based Electrochemical Filter Capacitors with High Frequency Response and Capacity Density

The adoption of super electrochemical capacitors (SECs) as replacements for aluminum electrolytic capacitors (AECs) in alternating current (AC) filter circuits has attracted significant research interest. This trend is primarily driven by their high specific capacitance and low space occupancy, making SECs promising candidates for future portable electronic devices. In this work, MBene was prepared through a simple one-pot hydrothermal reaction and first used as the electrode material for AC filtering symmetric SECs. Specifically, the devices exhibit a high specific area capacitance of 702 μF cm–2 and a large negative phase angle of 54.8° at 120 Hz, a small resistor-capacitor (RC) time constant of 0.96 ms, and high-rate capability up to 1000 V s–1. In addition, a theoretical investigation was conducted to examine the characteristics of ion diffusion and adsorption on the MBene surface. These MBene-based SECs open opportunities for the future development of portable power electronics.