A Microstructure-Resolved Model of Sodium-Ion Battery Hard Carbon Electrodes

Hard Carbon (HC) is one of the key materials for the development of state-of-the-art sodium-ion batteries. To improve the design and accelerate the adoption of this technology, it is necessary to understand the dynamics of sodium storage into HC and the contributions of the different sodiation phenomena. With this purpose, we developed a novel physics-based computational model that unravels the sodiation mechanism of HC electrodes. This model considers the explicitly 3D- resolved HC electrode microstructure at the mesoscale, operating in a half cell versus sodium metal. We have parameterized and validated this model with experimental data of the HC material (particle shape and size, skeletal density, and textural properties) and electrochemical data of the HC electrode (applied current and galvanostatic discharge profiles). Then, we used the model to investigate how manufacturing parameters (such as formulation and porosity) affect the 3D- resolved sodiation heterogeneities, impacting the electrochemical performance (e.g. capacity, potential). The influence of the C-rate was also studied with these performance descriptors. Overall, our model represents the first approach to create a flexible computational tool for researchers or engineers to assess the kinetic and transport limitations of their specific HC. Furthermore, it can help them understand the underlying sodiation phenomena taking place in their material via a direct comparison with their own galvanostatic profiles, and by considering the sodiation heterogeneities arising from the electrode’s three-dimensional microstructure, supporting the ramp-up in the production of sodium-ion batteries.