Alkali Metal Ion Insertion and Extraction on Non-Graphitizable Carbon with Closed Pore Structures

We compared the insertion and extraction behaviors of lithium and sodium ions in non-graphitizable carbon with closed pore structures heat treated 2073 K and non-graphitizable carbon without heat treatment to investigate the elemental difference of the charge-transfer reactions of alkali metal ions from a kinetic viewpoint. The lithium system has smaller kinetic parameters for the insertion/extraction reactions such as charge transfer resistance and activation energy compared to those in the sodium system. On the other hand, the diffusion coefficients of the lithium and sodium ions in non-graphitizable carbon are almost the same. Based on these results, we discuss the rate-determining process of charge-transfer reactions and provide a rational design of non-graphitizable carbon as an anode material for use in lithium ion and sodium ion batteries.