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This paper presents a physics-based model for lithium-ion battery degradation, specifically focusing on silicon-graphite composite anodes. The model incorporates key degradation mechanisms like SEI growth, particle cracking, and loss of active material, allowing for their disentanglement. The study investigates the impact of check-up frequencies on storage degradation and relates degradation to operating conditions, providing insights for battery optimization.
Silicon anodes don't just degrade faster, they degrade *differently*, and this physics-based model reveals how.
Higher energy density and longer lifetime are the requirements for next-generation lithium-ion batteries. A promising anode material is silicon, which offers high specific capacity, but its significant volume change during lithiation and delithiation enormously reduces battery lifetime. A physical understanding of the processes degrading the battery is key to mitigate this effect and advance in the field. We develop a physics-based model to describe degradation during battery cycling under various protocols and storage conditions, with varying check-up (CU) frequencies. The model can disentangle basic degradation mechanisms, such as the growth of the Solid-Electrolyte Interphase (SEI), from silicon mechanisms, such as particle cracking, SEI growth on cracks, and loss of active material (LAM). We investigate the impact of CUs on the observed storage degradation and the reason behind the increased degradation in batteries, including silicon in the anode. Additionally, we relate the observed degradation to operating conditions, enabling future optimization of battery use and design.
