Determination of Chemical Diffusion Coefficient of Lithium Ion in Graphitized Mesocarbon Microbeads with Potential Relaxation Technique

Conventional techniques have inevitable defects in measuring the chemical diffusion coefficient of Li ions in host materials. However, potential relaxation technique cannot only determine the of Li ions in host materials more accurately, but also can get the of Li ions in the electrolytes simultaneously. In this paper, the theory of this technique is demonstrated, and also the chemical diffusion coefficient of Li ions in graphitized mesocarbon microbeads is discussed in detail. It can be seen that during deintercalation is much higher than that during intercalation at low voltage. In addition is relatively large in the case of the coexistence of two phases and decreases steeply during phase transformation. As stage 1 is formed, the further insertion of lithium causes the continual reduction of during intercalation, and a similar case can be seen from the further extraction of Li ions from diluted phase 1. Furthermore this technique can be used to determine the of Li ions especially in solid and polymer electrolytes.