Advanced Powder Technology, Vol.31, No.11, 4491-4499, 2020
Rheological behavior of concentrated slurry and wet granules for lithium ion battery electrodes
Dynamic rheological behaviors of concentrated slurry and wet granules made of graphite, carboxymethyl cellulose, and water have been investigated, because there are few studies on wet granules despite the importance of controlling them. The internal structure and the rheological behaviors of the wet granules were compared with those of the concentrated slurry through the X-ray computed tomography (CT) observation and large amplitude oscillatory shear (LAOS) measurement. At small strain (1%), the concentrated slurry showed larger storage modulus G' than loss modulus G '', that is, tan delta (=G ''/G') less than 1.0. In contrast, the wet granules indicated larger G '' than G', that is, tand more than 1.0. This rheological behavior of wet granules seems to be attributed to the voids that was suggested to exist in the granular layer. On the other hand, at large strain (100%), the tand values of the wet granules were extremely higher than those of the slurry. It appears that this behavior of wet granules is due to the collapse of the granular layer indicated by the high second-harmonic intensities observed in the LAOS measurement. These results elucidated the change of rheological behavior from slurry to wet granules with increasing solid content. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
Keywords:Concentrated slurry;Wet granules;X-ray CT;Viscoelasticity;Large amplitude oscillatory shear