A Low Impedance, High Current, High Charge Density, Scalable and Soft Energy Converter

Flexible energy conversion devices, especially those based on low-frequency mechanical energy, are crucial for developing flexible electronics. Here, we report a flexible power generation device that utilizes ionic streaming potential to generate electrical output. Taking advantage of the Li-ion anchoring ability of the oxygen-containing functional groups on the activated carbon cloth and the PVA hydrogel backbone, exploiting the difference in ion concentration caused by deformation, our device can generate an electrical output with the short-circuit current being up to 4 mA, and the power density reaching 425 mW per square meter. At the same time, the internal resistance is only 122 ohms. After 7500 cycles, the device can still maintain 97.38% of the peak current output. The working parameters, such as electrolyte concentration, frequency and speed of the mechanical driving force, and carbon cloth oxidation time, were systematically studied and optimized. When used to harvest mechanical energy, the device demonstrated outstanding charging capability, charging a 2F capacitor from 0.34 mV to 30.1 mV in 371 s at 80 kPa pressure. The device can power in vitro wearable devices and medical applications such as electronically controlled drug release.