Cycling of silicon-based anodes typically involves the development of high levels of mechanical stress, due to the strong dependence of the molar volume of Li-Si compounds on the state of lithiation. Many strategies have been used to accommodate this stress, such as the development of tougher polymer binders, and the engineering of the size and distribution of Si-containing materials in the electrode. Here, we show that the consequences of these stresses can also depend on the macroscopic dimensions of the electrode. We fabricated a series of electrodes containing ≥ 60 wt% of Si and SiOx particles and tested them in both coin (1.54 cm2) and pouch cell (14.1 cm2) prototypes. Upon cycling under identical conditions, the anodes of the larger pouch cell electrodes exhibited visible rippling and deformation, while the anodes in smaller coin cells remained dimensionally stable. This mechanical evolution in larger anodes led to damage at various points of the electrode coating, facilitating the onset of Li plating and leading to accelerated cell failure. This size dependency of the mechanical behavior of silicon anodes will be discussed during the presentation, highlighting how innovation in battery sciences may benefit from validation at more relevant cell formats.

Cell format dependent mechanical damage in silicon anodes

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