2025 Volume 2025 Issue 307 Pages 43-45
Sodium-ion insertion and de-insertion into non-graphitizable carbon was studied from a kinetic viewpoint. The sodium-ion transfer reaction was evaluated separately for the effects of the electrolyte, the solid electrolyte interphase (SEI), and the structure of non-graphitizable carbon. In chapter 1, the sodium-ion transfer reaction was compared with the lithium-ion transfer reaction. The value of the sodium-ion transfer reaction was larger than that of the lithium-ion transfer reaction, indicating that the rate-determining step of sodium-ion insertion reaction was not the desolvation process. In chapter 2 and chapter 3, the effect of SEI on sodium-ion insertion and de-insertion was investigated. The magnitude of the charge transfer resistance was more affected by the SEI rather than the electrolytes. Furthermore, it was found that SEI with a large amount of NaF inhibited a large effect on the frequency factor in the charge transfer reaction. In chapter 4, the activation energies of sodium-ion transfer reactions for non-graphitizable carbon with various heat treatment temperatures were investigated. The non-graphitizable carbon with low heat-treated temperature had small activation energy. This result indicated that the activation energy was influenced by the structure of host materials.
