A design guideline of graphite/silicon composite electrode for extremely fast charging Li ion batteries

초록

Achieving extremely fast charging (XFC) capabilities is critical for the development of lithium-ion batteries (LIBs) for electric vehicles (EVs). However, conventional LIBs with graphite anodes face challenges with lithiation at high charging rates, often resulting in Li plating. Incorporating silicon (Si) with graphite to form graphite/Si composite electrodes presents a potential solution, but the detailed design rules for these composite electrodes are not yet well understood. Here, we systematically investigate the impact of varying Si content on the fastcharging behaviors of graphite/Si composite electrodes. Through electrochemical analysis, in-situ X-ray diffraction (XRD), and a newly developed reaction dynamics analysis cell, our research demonstrates that the lithiation reaction proceeds inhomogeneously and becomes increasingly concentrated on the Si component as the charging rate increases. Based on these findings, a physics-based model further explores the effects of Si properties and electrode design on XFC ability, proposing guidelines for designing advanced graphite/Si composite electrodes to achieve robust XFC abilities in LIBs.

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