Solid-state batteries (SSBs) with silicon anodes could enable improved safety and energy density compared to lithium-ion batteries. However, degradation arising from the massive volumetric changes of silicon anodes during cycling is not well understood in solid-state systems. Here, we use operando X-ray computed microtomography to reveal micro- to macro-scale chemo-mechanical degradation processes of silicon anodes in SSBs. Mud-type channel cracks driven by biaxial tensile stress form across the electrode during delithiation. We also find detrimental cracks at the silicon/solid electrolyte interface that form due to local reaction competition between neighboring domains of different sizes. Continuum phase-field damage modeling quantifies stress-driven channel cracking and shows that the lithiated silicon stress state is critical for determining the extent of interfacial fracture. This work reveals the mechanisms that govern SSBs compared to conventional lithium-ion batteries and provides guidelines for engineering chemo-mechanically resilient electrodes for high-energy batteries.

中文翻译：

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硅负极固态电池中的断裂动力学


与锂离子电池相比，带有硅负极的固态电池 （SSB） 可以提高安全性和能量密度。然而，在固态系统中，硅阳极在循环过程中的巨大体积变化引起的退化并不十分清楚。在这里，我们使用原位 X 射线计算机显微断层扫描来揭示 SSB 中硅阳极的微观到宏观尺度的化学机械降解过程。在脱锂过程中，由双轴拉伸应力驱动的泥浆型通道裂纹会在电极上形成。我们还发现了硅/固体电解质界面处由于不同大小的相邻域之间的局部反应竞争而形成的有害裂纹。连续相场损伤模型量化了应力驱动的沟道开裂，并表明锂化硅应力状态对于确定界面断裂的程度至关重要。与传统锂离子电池相比，这项工作揭示了控制 SSB 的机制，并为高能电池的化学机械弹性电极的工程设计提供了指南。