A Modeling Framework of Electrochemo-Mechanics of Lithium-Ion Battery: Part I. Impedance Response of Single Particle

An impedance model considering the electrochemo-mechanics of a single particle in lithium-ion batteries is proposed in the work. In this model, the interaction between the Li+ diffusion and the surface reaction and mechanics is considered. The characteristic semicircle in low frequency range, which is due to the stress effect, is found. The visualizability of the stress-induced semicircle in the experiments is found to be related to the characteristic frequency of the Li+ diffusion. Through simplifying the model expression under three different limiting cases, two dimensionless number alpha=-theta RT/F/partial derivative U/partial derivative c(s) beta=1+theta(c(s)) over bar are defined to evaluate the stress effect. The proposed mechanic-modified model is verified through the results of thin-film electrode considering the difficulty in performing single particle experiments for nano-sized particle and similarity of the single particle and thin film electrode. This work can be supplemented with the theory of porous electrode to analyze the impedance response of a porous electrode, which will be discussed in the next part of this series of papers.