Structurally integrated 3D vertically porous Ni@NiOx(MnOx) electrode for high-performance filter electrochemical capacitor

Electrochemical capacitors (ECs) have the potential to replace bulky aluminum electrolytic capacitors (AECs) to meet the miniaturization demands of electronic components. However, the complex electrode material structure of ECs leads to slow ion diffusion, limiting their frequency response capability (<1 Hz). Although direct pore-structured design of carbon-based materials have been explored to enhance frequency response, there are some limitations: the loose porous structure reduces ion storage sites, inevitably causing capacitance loss. To address this issue, vertically porous Ni@NiO_x(MnO_x) (VPN@MO) composite electrodes are fabricated through dealloying and electrochemical oxidation to simultaneously promote frequency characteristics and capacitance. Benefiting from pseudocapacitive properties of NiO_x(MnO_x) and vertically interconnected structure that allows for fast ion transport, the VPN-EC demonstrates an excellent areal capacitance of 1.48 mF/cm² with a phase angle of −81^° at 120 Hz. Furthermore, an asymmetric capacitor (ASPC) with a high energy density of 936 µFV²/cm² at 120 Hz is constructed and a novel assemble technology without any loss in capacitance was proposed. The integrated 3 × 3 ASPC array could expand the voltage window to 3.6 V without any capacity loss, efficiently converting various AC waveform into a stable DC output (V_ripple=30 mV is approximate 1/10th of that AECs (280 mV)). This ASPC displays excellent integrability. When connected to a wind turbine, the integrated ASPCs continuously powered LEDs. These findings would provide a new method and structure for developing rapid response, high specific capacitance and a wide range of operating voltage.