Revealing the Rate-Limiting Li-Ion Diffusion Pathway in Ultrathick Electrodes for Li-Ion Batteries
Publication Type:
Journal
Authors:
Co-Authors:
Han Gao, Qiang Wu, Yixin Hu, Khalil Amine, and Zonghai Chen
Year Published:
2018
Abstract:
Increasing the loading of active materials by thickening the battery electrode coating can enhance the energy density of a Li-ion cell, but the trade-off is the much reduced Li+ transport kinetics. To reach the optimum energy and power density for thick electrodes, the effective chemical diffusion coefficient of Li+ (DLi) must be maximized. However, the diffusion of Li+ inside an electrode is a complex process involving both microscopic and macroscopic processes. Fundamental understandings are needed on the rate-limiting process that governs the diffusion kinetics of Li+ to minimize the negative impact of the large electrode thickness on their electrochemical performance. In this work, lithium Ni–Mn–Co oxide (NMC) cathodes of various thicknesses ranging from 100 to 300 μm were used as a model system to study the rate-limiting diffusion process during charge/discharge. The rate-limiting diffusion coefficient of Li+ was investigated and quantified, which was correlated to the electrochemical performance degradation of thick electrodes. It is revealed here that the under-utilization of the active material was caused by the limited diffusion of Li+ inside the porous electrode, leading to a critical electrode thickness, beyond which the specific capacity was significantly reduced.
Journal:
The Journal of Physical Chemistry Letters
Volume:
9
Issue:
17
Pagination:
5100-5104
ISSN:
Short Title:
Date Published:
8/21/2018