Fast charging of alkali-ion batteries at the single-particle level: the impact of particle geometry on diffusional and kinetic bottlenecks in voltammetry

Shedding light onto the processes that limit the fast charging of alkali-ion battery cells constitutes a hotspot area. In the present work, we study two of the most important ones at the microscopic level: charge transfer at the interface and diffusion of ions inside the electrodes, focusing on how the geometry of particles regulates these kinetic limitations. The results are presented in maps of reversibility and finiteness of diffusion constructed from hundreds of voltammetric numerical simulations at different operating conditions. The diagrams obtained with different geometries are given a straightforward physical interpretation. This helps to understand in depth the phenomena that regulate the charging of cells, and so to promote a rational design of fast-charging electrode materials.