Characterization of Elasticity for Silicon‐Containing Anodes by Microindentation

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
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effective measurement method for characterizing PECs, thereby facilitating the
development of mechanical models for multidisciplinary cell simulations.