Characterization of Elasticity for Silicon‐Containing Anodes by Microindentation

Abstract

The intricate internal stresses within porous electrode coatings (PEC) are induced by charging and discharging of lithium-ion batteries. The incorporation of silicon-based particles in the anode further exacerbates the volume change of active particles and the microstructure change of PECs during battery cycling. This highlights the urgent need for a mechanical model of the PEC in electrochemically and mechanically coupled cell simulations. The first step to develop such a model is a layer-resolved, homogenized mechanical characterization of the PEC. In cylindrical cells, the mechanical properties of the PEC are highly nonlinear due to its multiphase granular microstructure combined with its thin, rolled geometry inside the cell housing. Herein, microindentation is employed and analyzed to extract the one-dimensional mechanical response of a single PEC-layer. Three major challenges of microindentation, thermal drift, substrate effect, and tip size effect are overcome. Quantification of short-term elasticity as well as long-term viscoelasticity is done for a silicon-containing dry anode sample by the proposed workflow. The results demonstrate that microindentation is a suitable and effective measurement method for characterizing PECs, thereby facilitating the development of mechanical models for multidisciplinary cell simulations.