In-situ 4D Evaluation of Carbon-Black Volume Fraction in Stirring Process of Secondary Battery Cathode Material Slurry by Multi-Layered Electrical Resistance Tomography (mlERT)

Abstract

The 4D (3D spatial + 1D temporal) mixing state of Carbon-Black (CB) volume fraction α in stirring processes of secondary battery cathode slurry by multi-layered electrical resistance tomography (mlERT) has been evaluated by the mean and dispersion of conductivity from the three axes of r, θ, and z for identifying the distribution factors of CB. Experiments were conducted with stirring time t = 0–360 s and stirring speed ω = 200, 400, and 720 rpm. From the experimental results, the influence of the cathode slurry material of the initial conditions was confirmed from the θ-t space, the blade position from the z-t space, and the shape of the stirring vessel from the r-t space, respectively. By comparing the three types of ω, the conductivity converged to 0.023 only for ω = 720 rpm, which is consistent and indicates the complete stirring by converged value to 0 (no bias as close to 0).