Electrochemically driven mechanical energy harvesting

• Published in: Nature communications Vol. 7; no. 1; p. 10146
• Main Authors: Kim, Sangtae, Choi, Soon Ju, Zhao, Kejie, Yang, Hui, Gobbi, Giorgia, Zhang, Sulin, Li, Ju
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.01.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/544; 639/301/299; 639/638/440; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Energy-Generating Resources; Humanities and Social Sciences; Mechanics; Membranes, Artificial; multidisciplinary; Science; Science (multidisciplinary); Thermodynamics
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10146

Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress–voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson’s ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition–voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities. There is intensive research underway into the development of various mechanical energy harvesters. Here, the authors report an electrochemically driven mechanical energy harvester that uses the stress-induced potential difference of lithiated silicon electrodes to generate continuous electricity.