Operating commercial LiNi_xCo_yMn_{1–x –y}O₂(NMCs)/ graphite cells at a higher voltage cut-off would deliver a higher energy density. This protocol has been broadly investigated in the literature, and connected with the occurrence of a rapid and severe degradation. In particular, these studies point to a de-coupling between capacity fade (mostly located on graphite) and impedance rise (mostly located on NMC). However, in the present work we unveil a non-negligible contribution of NMC111 to the total capacity fade, not reported in other studies. This unexpected feature is addressed by means of an experimental and modelling approach apt to unveil the causes behind it, and to quantify the relative impact of different, concurrent ageing mechanisms. For this purpose, a physics-based model including different ageing modes is proposed, and cross-validated on Direct and Alternate Current measurements. The fitting reveals that the capacity loss on NMC111 is in fact coupled to its characteristic impedance rise, and the parameters thus extracted are further validated by means of surface and bulk analytical techniques. In this way, the physical validity of these parameters is confirmed, and they can thus be used for lifetime prediction of NMC/graphite cells operated at high voltage. In addition, we investigate how the occurrence of a non-negligible capacity loss on NMC111 impacts the uneven stoichiometric drift occurring in the jelly roll of commercial cells, while demonstrating how lab-scale cells can still be used for representing the behaviour of commercial devices. It is revealed how high temperatures and localized Li plating can potentially push NMC111 above the chosen upper voltage cut-off, with a consequent increase in the degradation rate at cell-level.

商用LiNi _x Co _y Mn _{1–x –y} O ₂（NMC）/更高截止电压的石墨电池将提供更高的能量密度。该协议已在文献中进行了广泛研究，并与快速而严重的降级有关。特别地，这些研究指出了容量衰减（主要位于石墨上）和阻抗上升（主要位于NMC上）之间的去耦。但是，在当前的工作中，我们揭示了NMC111对总容量衰减的不可忽略的贡献，其他研究没有报道。通过一种实验和建模方法可以解决此意外的问题，该方法易于揭示其背后的原因，并量化不同的并发老化机制的相对影响。为此，提出了一种基于物理的模型，其中包括不同的老化模式，并在直流电和交流电测量中进行交叉验证。拟合表明，NMC111上的电容损耗实际上与其特性阻抗的上升有关，因此，通过表面和本体分析技术进一步验证了如此提取的参数。以这种方式，证实了这些参数的物理有效性，并且因此可以将它们用于在高压下操作的NMC /石墨电池的寿命预测。此外，我们研究了NMC111上不可忽略的容量损失的发生如何影响商用电池的果冻卷中发生的化学计量不均匀漂移，同时展示了实验室规模的电池如何仍可用于表示商用设备的行为。