Numerical modeling of electrochemical transport and discharge mechanisms in hierarchically porous lithium-ion electrodes

Abstract

Hierarchical porous microstructures are promising candidates for lithium battery electrodes that maintain capacity and specific energy at high charging and discharging rates. The electrolyte channels embedded in these structures facilitate Li transport throughout the active material such that the accessible capacity is enhanced. We performed numerical simulations of the discharge process for four modeled electrode structures in order to investigate the impact of the size of electrolyte channels on the electrochemical performance. The results show that the size ratio of the electrolyte channels and active materials columns determines the discharge characteristics of hierarchical porous electrodes. Depending on the size ratio, electrodes discharge from the separator side and the current collector simultaneously which can enhance the accessible capacity and specific energy. The results from our simulations can aid in designing tailored hierarchical porous electrode structures for fabrication of electrodes with enhanced capacity and rate capability.