Rheological interpretation of the structural change of LiB cathode slurry during the preparation process

Abstract

The dispersion behavior of lithium cobalt oxide (LCO) and acetylene black (AB) particles in the preparation process of the cathode slurry of LiB is investigated from the rheological viewpoint. The cathode slurry is considered as the dispersion of coarse LCO particles in the viscoelastic AB slurry. Viscosity as well as loss modulus of the cathode slurry are estimated from those of the AB slurry using and compared the measured results. After forming the AB network structure or When AB content is high enough, LCO particles can enter and destroy the AB network structure. As a result, LCO particles and fragmented AB network structures are homogeneously mixed, exhibiting better discharge performance. Once the cathode slurry is excessively diluted, the LCO particles are excluded from the AB network structure, resulting in low discharge capacity. Over fragmentation using a high-shear device causes the AB network structure into too small segments, which also lowers the battery performance. Viscosity is helpful to understand the entrance of LCO particles into the AB network, and the storage modulus detects the destruction of the AB network structure during the preparation process of cathode slurry. • Cathode slurry is the mixture of isolated LCO particles and viscoelastic AB slurry. • Rheology of cathode slurry reflects AB network structure and LCO location. • LCO particles can play a role to destroy AB network like a ball-milling effect. • Entrance of LCO into AB network is crucial to obtain favorable cathode slurry.