How Pore Parameters Affect Li Ion Depletion in Mesoporous Materials for Lithium-Ion Batteries

In lithium-ion batteries, enhancing the diffusion of lithium ions through the electrolyte is one of the most important factors in maximizing the utilization of active material at high current densities. In this regard significant efforts to use mesoporous material as an active material have been attempted. However, it has not been well understood how pore parameters, such as pore size, particle size, and tortuosity of the mesoporous materials, affect the electrochemical performance. In this study, three-dimensionally ordered mesoporous titania with different pore and particle sizes synthesized by a hard template method using a size-tunable silica particle and a commercial titania particle with random mesopores were used to investigate the effects of these parameters on the electrochemical performance. Furthermore, a mathematical model, frequently used for a porous catalytic systems, was employed to rationalize the experimental results by introducing the Thiele modulus parameter. The model derived from combining experimental data and the Thiele modulus parameter suggests the criteria when Li ion depletion starts. These findings can help us develop strategies to enhance the electrochemical performance of mesoporous materials by optimizing their structural parameters.