Characterization of electrochemical kinetics of SiOx using single-particle electrode technique: An impedance study

In this study, single-particle electrode technique is adopted to measure the impedance response of SiOx materials for the first time. The electrochemical impedance spectroscopies of two SiOx particles are measured at different insertion ratios and different temperatures. Two kinetic parameters, namely Li+ diffusivity and exchange current density, are obtained using our previously proposed impedance model which takes into account the stress effect on Li+ diffusion and surface reaction. The dependence of the two parameters on the Li+ insertion ratio and temperature is obtained. The fitted results are found to be strongly consistent with previous research. Lastly, through comparison with the results of earlier studies with the help of the single-particle electrode technique, we find that the kinetic performance of SiOx is much poorer than graphite, and smaller particles are recommended to use compared with graphite when applying SiOx as the anode material. The single-particle electrode can serve as an effective tool to evaluate the electrochemical kinetics of various materials and provides a new index for material evaluation.