Boosting the output of hydrocapacitors by structure modification

Due to the depletion of fossil fuels and the corresponding global warming problems, harvesting energy from the ambient environment has aroused extensive interest to satisfy the urgent energy demand. This work presents a lightweight and compact hydrocapacitor with a simple sandwich structure demonstrating superior output performance. Without an external electric power supply, a single device could produce a maximum output voltage of 0.74 V and a maximum short-circuit current of 54 mA/cm2 with a small-scale H2SO4 solution droplet, which corresponds to the high power density of 142.71 mW/g. Furthermore, scaling up devices in series to light up an LED demonstrates its good extensibility and applicability. The self-charging behaviors of the hydrocapacitors based on streaming potential have been discussed. This simple structured hydrocapacitor may pave the way for the exploration of new-type renewable energy conversion and storage technologies.