Particle dispersion behaviors in Lithium Ion Battery (LIB) are clarified by Electrochemical Impedance Spectroscopy (EIS) method based on the dielectric characteristics of cathode slurry, which are Carbon Black (CB) aggregation, CB-bare LiCoO2 particles, CB path and CB-coated LiCoO2 particles. The experimental particle dispersion behaviors are evaluated by numerical simulation. In the experiments, cathode slurry is stirred under different rotational speed n; meanwhile, in the simulation, medium conductivities sigma(m) and particle conductivities sigma(p) in cathode slurry model are changed. Herein, CB aggregation and CB path are verified by sigma(m), while CB-bare LiCoO2 particles and CB-coated LiCoO2 particles are verified by sigma(p). Compared with sigma(p), sigma(m) plays important roles in determining particle dispersion behaviors because sigma(m) has the similar functions as n to change characteristic resistances R-cL and R-cH and characteristic frequencies f(cL) and f(cH). Therefore, compared with CB-coated LiCoO2 particles, CB path dominates the conductivity of cathode slurry in LIB. Furthermore, the dielectric characteristics of NMP solution, CB-NMP slurry and LiCoO2-NMP slurry are investigated to clarify how each component of cathode slurry contribute to the whole Nyquist plot. The results show that the straight line is caused by adding CB, while low frequency semi-circle is caused by CB-bare LiCoO2 particles. Electrical impedance spectroscopy (EIS) method, Lithium ion battery (LIB). (C) 2019 The Electrochemical Society.