Stress fields in hollow core–shell spherical electrodes of lithium ion batteries

Abstract

This paper presents a comprehensive model coupling the effects of hydrostatic stress, surface/interface stress, phase transformation and the structure of electrodes. First, the governing equation of moving phase interface with hydrostatic stress is established. Under the effect of hydrostatic stress, phase transformation process is much faster, which means phase transformation time is overestimated in previous publications. Then, a cross-scale analysis is presented to investigate the size effect owing to hydrostatic stress, surface stress and interface stress separately, which concludes that the effect of hydrostatic stress is significant for the stress field in microelectrode particles, whereas that of surface/interface stress is highlighted in nano-ones. Finally, an electrochemical variable 'efficiency' (ratio of effective capacity over total capacity) is defined. The advantages of hollow structure electrodes on stress and efficiency are analysed. The present model is helpful for the material and structure design of electrodes of lithium ion batteries.

Stress Analysis of Electrode Particles in Lithium-Ion Batteries

“…Multiple models have been developed to address the phase transformation-induced discontinuities in concentration and stress fields. However, the inverse effect of the stress fields on the phase transformation has not been well studied, until the recent work of current authors [47]. Liu et al [47] proposes a fully coupled system which investigates the interactions between phase transformation and stress fields, which will be discussed in this chapter.…”

“…Although the surface effect of electrode particles has been reported for several years [11], the interface stress is not considered until the recent work of the authors [47]. In fact, for hollow electrode particles, the surface stress at the inner and outer surfaces are just special cases of interface stress Eq.…”

“…Three stages of the hollow LiCoO 2 particles in discharging process: (a) α and β phases coexist; (b) α phase only; (c) β phase only (reproduction from[47]). …”

“…Concentration distribution of the electrode particle: (a) with α phase only; (b) with both α and β phases; (c) with β phase only (some data are reproduced from[47]). …”

“…Stress field in the biphase electrode: (a) radial stress; (b) hoop stress (some data are reproduced from[47]). …”