ABSTRACT The chemical diffusion coefficient in LiNi1/3Mn1/3Co1/3O2 was determined via the galvanostatic intermittent titration technique in the voltage range 3 to 4.2 V. Calculated diffusion coefficients in these layered oxide cathodes during charging and discharging reach a minimum at the open-circuit voltage of 3.8 V and 3.7 V vs. Li/Li+, respectively. The observed minima of the chemical diffusion coefficients indicate a phase transition in this voltage range. The unit cell parameters of LiNi1/3Mn1/3Co1/3O2 cathodes were determined at different lithiation states using ex situ crystallographic analysis. It was shown that the unit cell parameter variation correlates well with the observed values for chemical diffusion in NMC cathodes; with a notable change in absolute values in the same voltage range. We relate the observed variation in unit cell parameters to the nickel conversion into the trivalent state, which is Jahn-Teller active, and to the re-arrangement of lithium ions and vacancies.

中文翻译：

---

通过电化学和晶体学分析确定层状氧化物的相变

摘要 LiNi1/3Mn1/3Co1/3O2 中的化学扩散系数是通过恒电流间歇滴定技术在 3 到 4.2 V 电压范围内测定的。计算的这些层状氧化物阴极在充放电过程中的扩散系数在开路时达到最小值相对于 Li/Li+ 的电压分别为 3.8 V 和 3.7 V。观察到的化学扩散系数的最小值表明该电压范围内的相变。LiNi1/3Mn1/3Co1/3O2 正极的晶胞参数在不同锂化状态下使用非原位晶体学分析确定。结果表明，晶胞参数变化与 NMC 阴极中化学扩散的观察值密切相关；在相同电压范围内，绝对值变化显着。