Mechano-Electrochemistry – Towards Structural Batteries and Energy Harvesters

Abstract

Lithium ion batteries have revolutionized our modern society and have catalyzed the growth of advanced technologies such as electric vehicles and portable electronic devices. Batteries are dynamic mechano-electrochemical systems where the components and interfaces are subjected to significant mechanical stresses and strains during operation. Most current research approaches discard the coupled mechanical processes as an unavoidable byproduct. However, the coupling between mechanics and electrochemistry, mechano-electrochemical coupling, is a powerful yet unexplored tool. In this regard, our research efforts so far have been aimed at understanding and isolating this fundamental phenomenon followed by developing new classes of energy devices that leverage these findings for several unique applications. First, using principles of elastic strain engineering, we have demonstrated controllable modulation of electrochemical parameters governing energy storage systems as a function of applied strain. Next, building off these findings, we developed electrochemical-mechanical energy harvesters for harnessing ambient mechanical energy at very low frequencies (<5 Hz), a regime where the conventional state of the art piezoelectric and triboelectric energy harvesters have drastically reduced performances. The unique frequency tuning capabilities in this class of energy harvesters enable development of devices for use in human motion harvesting/sensing applications and multifunctional transient energy harvesting/storage devices. Additionally, to further understand the relationship between mechanical and electrochemical properties, we developed multifunctional structural supercapacitor and ultra-battery composites for use in load-bearing applications. Overall, our findings provide a broad framework for using mechano-electrochemistry as a design tool for developing next generation energy storage devices.