Abstract Li ion concentration-dependent mechanical properties and stress of electrodes are crucial to the performance and durability of lithium-ion batteries. Here, we report in situ measurements of the elastic modulus and stress of a commercial graphite composite electrode during lithiation/delithiation cycling. To realize the in situ measurements, the real-time curvature change of cantilever graphite electrodes in a home-made transparent cell was captured by a CCD camera during cycling. The elastic modulus and stress were derived from the curvature change of cantilever electrodes using a mechanical model, developed in this study. The elastic modulus increases from an initial value of ca.8.9 GPa to ca.31.9 GPa when the state of charge (SOC) is 60% during the second lithiation. The magnitude of the stress increases during lithiation process, and changes from compressive stress to tensile stress in the thickness direction. These findings are helpful for modeling efforts to understand the degradation and optimize the design of commercial graphite electrodes.

中文翻译：

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商业石墨电极机械性能和应力演变的原位测量

摘要 锂离子浓度依赖的机械性能和电极应力对锂离子电池的性能和耐久性至关重要。在这里，我们报告了在锂化/脱锂循环过程中商业石墨复合电极的弹性模量和应力的原位测量。为了实现原位测量，在循环过程中通过CCD相机捕获自制透明电池中悬臂石墨电极的实时曲率变化。使用在本研究中开发的机械模型，弹性模量和应力来自悬臂电极的曲率变化。当第二次锂化期间荷电状态 (SOC) 为 60% 时，弹性模量从约 8.9 GPa 的初始值增加到约 31.9 GPa。锂化过程中应力的大小增加，并且在厚度方向上从压应力变为拉应力。这些发现有助于建模工作以了解降解和优化商业石墨电极的设计。