Heterogeneous Solid-Electrolyte Interphase in Graphite Electrodes Assessed by 4D-Resolved Computational Simulations
Résumé
Graphite is one of the most used active materials in lithium-ion battery negative electrodes thanks to its high specific capacity and low equilibrium potential. For over 40 years, one of the most discussed issues with this material revolves around the complex formation mechanism of the solid-electrolyte interphase (SEI), which acts as a protective layer against electrolyte decomposition but causes capacity losses. Due to the difficulties to experimentally observe the SEI (air sensibility, low contrast and nanometric size), its impact on the performance of graphite-based porous electrodes has never been spatially assessed in regards of the three-dimensional features of the electrodes. We report here a new 4D (3D+time) resolved computational model which gives insights about the SEI heterogeneity within such porous electrodes. The model is applied to different graphite morphologies and is able to assess the electrode mesostructure impact on the SEI formation and the impact of the latter on the electrodes' electrochemical performance. This work paves the way towards a powerful tool to assist in the interpretation of SEI characterization experiments.