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

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.