Electrochemical systems for harvesting kinetic energy from solvation Gibbs free energies of Prussian blue analogues

• Main Author: Lee, Donghoon
• Other Authors: Lee Seok Woo
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Chemistry; Physics; Energy harvesting; Kinetic energy harvesting; Battery
• Online Access: https://hdl.handle.net/10356/180979
• Institution: Nanyang Technological University

Kinetic energy harvesting holds great promise, but current approaches, such as systems based on friction and deformation, typically require high-frequency inputs and highly durable materials. Here, we introduce an electrochemical system featuring a two-phase immiscible liquid electrolyte and Prussian blue analogue electrodes to harvest low-frequency kinetic energy. This system transforms translational kinetic energy from the movement of electrodes between different electrolyte phases into electrical energy, achieving a peak power output of 6.4 ± 0.08 μW cm−2, with a peak voltage of 96 mV and a peak current density of 183 μA cm−2 using a 300 Ω load, which is significantly smaller than loads commonly used in traditional methods. The charge density reaches 2.73 mC cm−2, and the energy density measures 116 μJ cm−2 during a single harvesting cycle. Additionally, the system maintains a continuous current of around 5 μA cm−2 at 0.005 Hz over 23 cycles without performance degradation. The voltage generation is driven by the difference in solvation Gibbs free energy between the two electrolyte phases. We further demonstrate the system’s capability in a microfluidic harvester, achieving a peak power density of 200 nW cm−2 by converting kinetic energy as the electrolyte flows through a microfluidic channel into electrical power.