Probing silicon lithiation in Si-C/graphite blended anodes with a dedicated Newman performance model
Journal
J ELECTROCHEM SOC
Date
2020.08.07
Abstract
Blended negative electrodes with a mix of graphite and silicon are attractive candidates to extend the energy density of lithium-ion batteries. Given the huge volume expansion of silicon, the relative lithiation/delithiation of both active materials upon cycling is crucial to determine the mechanical behavior of the electrode but is complicated by the potential hysteresis displayed by silicon. In this study, a Newman based model has been adapted to probe lithiation and delithiation in a blended anode with 16％ SiC@1500mAh/g mixed with 84％ graphite. In particular, an original SiC composite model has been developed to account for the morphology of the SiC composed of nanoflakes of silicon embedded in a carbon matrix. The developed physic-based model is parametrized with dedicated experiments and has been validated for two electrodes loadings at various temperatures and C-rates. Once validated, the model allows to probe the lithiation competition between silicon, composite’s carbon and graphite at different C-rates. In particular, we show that at higher C-rate, lithiation of silicon is delayed and reduced compared to the graphite one, which could be favourable as aging is mainly due to silicon expansion.
Reference
Journal of The Electrochemical Society, 2020 167 120506