Vibration-to-electric energy conversion via electric double layer redistribution of graphene-nickel foam electrode

In this work, the vibration-to-electric energy conversion is studied with the nanoporous graphene-nickel foam (G-NF) electrode through the redistribution of the electric double layer (EDL) on the interface between Potassium chloride (KCl) solution and nanoporous graphene when the KCl solution vibrationally flows through the G-NF electrode. Here, the G-NF electrode is prepared by electro-depositing graphene on the nickel foam and subsequently freeze-drying to get nanoporous structure. Because of good connection of the nanoporous graphene, a significant electrical voltage is generated, i.e. 0.3 V at KCl concentration 0.075 mol L⁻¹ and vibration frequency 10 Hz. Moreover, the voltage increases with the vibration frequency and gradually approaches to a saturated value for the frequency larger than 10 Hz. While, the voltage first increases and then decreases with the increasing of KCl concentration, and the peak voltage is gotten at the concentration 0.075 mol L⁻¹. Based on the discharging experiments, the energy conversion efficiency is calculated which gives a peak value 13.29% at 0.6 mol L⁻¹ KCl solution for the G-NF-4 electrode. The vibration-to-electric energy conversion system can be used to harvest the wave energy and kinetic energy, which may provide a lot of potential applications for the energy supply of wireless devices. © 2019 The Electrochemical Society.