Highly Stable and Eco-friendly Marine Self-Charging Power Systems Composed of Conductive Polymer Supercapacitors with Seawater as an Electrolyte

A self-charging power system harvesting random and low-frequency wave energy into electricity provides a promising strategy for the construction of smart oceans. However, the system faces huge challenges of easy corrosion in the marine environment and the utilization of toxic organic electrolytes in energy storage devices. To address the issues above, a seawater supercapacitor (SWSC) for the marine self-charging power system is rationally proposed by using a conductive polymer, polypyrrole with hollow morphology (h-PPy), to enhance the stability and capacitance while using seawater as an eco-friendly electrolyte to reduce the cost and achieve sustainability. The hollow design provides a shortcut for the ion transportation of seawater into the h-PPy electrode, and the SWSC achieves a high power density of 4.32 kW kg-1 under an energy density of 5.12 W h kg-1. Even after 180 days in seawater, h-PPy still endows a mass retention of 99.9%, enabling the SWSC to maintain a stability of 99.3% after 6000 cycles. More importantly, when combined with a TENG module as the marine self-charging power system to harvest wave energy, the system provides a stable output in water wave to drive electronics and sensors, which shows a competitive potential in the smart ocean and marine internet of things.