NiTe2-based electrochemical capacitors with high-capacitance AC line filtering for regulating TENGs to steadily drive LEDs

Highlights: • AC line filtering capacitor based on transition metal telluride has been developed. • High frequency response, superior capacitance, and low ripple voltage are realized. • The filtering can be well completed for AC signals with different waveforms. • NiTe₂ AC line filtering capacitor can readily regulate TENGs to drive LED steadily. Recently, electrochemical capacitors (ECs) have attracted consideration as AC line filter capacitors to replace the current aluminum electrolytic capacitors (AECs), which is an important direction of circuit integration miniaturization. In this work, a simple one-step hydrothermal method without additives was used to prepare vertically oriented NiTe₂ nanosheets on nickel foam, which provides large surface area and fast charge transport. The NiTe₂ ECs exhibit true pseudocapacitive nature, stable rate capability, efficient charge transport and high cyclic stability. In addition, they also deliver a super high specific area capacitance of 846.47 μF cm⁻² at 120 Hz, while retaining small resistor-capacitor (RC) time constant of 1.01 ms and large negative phase angle of 52.7°, indicating its excellent filtering performance. As expected, the NiTe₂ ECs perform evidently better filtering effect than commercial AECs when used as filter capacitors in circuits. From a practical point of view, we applied the NiTe₂ filter capacitor to regulate the triboelectric nanogenerator (TENG) output, successfully supplying a light-emitting diode (LED) in a steady state. The NiTe₂ filter capacitor proposed in this work can be fully used as a large-capacitance, small-size filter capacitor for portable devices and also applied to actual AC line circuits in the future.