Cathode particle fracture is widely recognised as a major degradation mechanism in lithium-ion batteries, yet cracking also permits electrolyte wetting of newly exposed internal surfaces, modifying interfacial reaction pathways. The mechanistic role of electrolyte wetting in redistributing reactions within cracked particles remains unclear. Here, we isolate this effect through a controlled comparison between (i) a fully coupled electro-chemo-mechanical model resolving lithium concentration, electrostatic potential, and stress fields in both the active material and the electrolyte inside and outside cracks, and (ii) a single-particle chemo-mechanical model employing the conventional uniform flux assumption. The coupled model predicts strong spatial heterogeneity in interfacial reaction rates, with flux amplification approximately 8x relative to the imposed uniform flux at the crack tip. Reaction redistribution, and thus lithium flux, is governed predominantly by local solid-state lithium concentration and stress variations, while electrolyte potential gradients inside cracks remain secondary under the conditions considered. Uniform flux models can underpredict delivered capacity by 25% at 1C-rate; this discrepancy increases at higher rates. They also underestimate tensile stresses throughout the delithiation process by 10%, directly affecting crack driving conditions. These results demonstrate that neglecting crack-electrolyte coupling leads to systematic underestimation of both utilisation limits and fatigue-relevant stress histories.

翻译：阴极颗粒碎裂被广泛认为是锂离子电池的主要退化机制，然而裂纹也允许电解液润湿新暴露的内部表面，从而改变界面反应路径。电解质润湿在裂纹颗粒内重新分布反应中的机制作用仍不清楚。本文通过(i)全面耦合的电-化学-力学模型（解析活性材料以及裂纹内外电解液中的锂浓度、静电势和应力场）与(ii)采用传统均匀通量假设的单颗粒化学-力学模型之间的受控比较，隔离了该效应。耦合模型预测界面反应速率存在强烈的空间异质性，裂纹尖端的通量相较于施加的均匀通量放大约8倍。反应重新分布（进而锂通量）主要由局部固态锂浓度和应力变化主导，而在所考虑条件下裂纹内的电解质电位梯度仍是次要因素。均匀通量模型在1C倍率下可能低估容量达25%；该差异在更高倍率下进一步增大。它们还在整个脱锂过程中低估了10%的拉伸应力，直接影响裂纹驱动条件。这些结果表明，忽略裂纹-电解质耦合将导致对利用极限和疲劳相关应力历史的系统性低估。