Modulation of diffusion kinetics and cyclic hysteresis of Li-alloy electrodes by deformation-diffusion coupling
Yifan Gao (Georgia Institute of Tech.), Min Zhou ()
Lithium ion batteries: When Chemistry meets Mechanics
Tue 4:20 - 5:40
Salomon 003
In Li-ion battery design, besides higher capacity and longer cyclic life, faster operational charging rate and higher energy efficiency are two other important desiderata which require the enhancement of lithium transport kinetics. Previous studies show that the coupling between stress development and diffusion can enhance or retard Li transport, depending on whether stresses are high enough to induce plastic deformation. Here, the modulation of diffusion kinetics and cyclic hysteresis of Li-alloy electrodes by this coupling is investigated. It is found that the diffusion speed, hence the operational charging rate, is highly sensitive to the electrode dimensions: larger electrode sizes not only imply longer diffusion distances, but also lead to higher likelihood of plastic deformation which diminishes the beneficial effect of stress enhancement to diffusion. This neutralization of the stress-enhanced diffusion effect also induces wider gaps in the potential-capacity hysteresis associated with charge-discharge, resulting in higher energy loss and more intense heating. The results highlight the benefit of reducing electrode particle size from the perspective of operational charging rate and energy efficiency.