Morphological Structure Characterizations in Lithium-Ion Battery (LIB) Slurry under Shear Rotational Conditions by On-Line Dynamic Electrochemical Impedance Spectroscopy (EIS) Method

Abstract

The morphological structure characterizations of Lithium-ion battery (LIB) slurry have been clarified under shear rotational conditions of rotation speed n and rotation time t by on-line dynamic electrical impedance spectroscopy (EIS) method. The EIS Nyquist and Bode plots are fitted by 10-parameter electrical equivalent circuit (10p-EEC) to clarify electrochemical characteristics which are resistance, reactance and peak frequency of LIB slurry. Then, the on-line dynamic resistance of conductive path Rp, the time-averaged capacitances of PVDF-CB double layer Cdl and PVDF-NMP solution CSO are obtained, which results in the following morphological structure characterizations of LIB slurry. The network structure of LIB slurry is deteriorated in the low rotation speeds of n = 50 rpm and n = 150 rpm and is well constructed in the high rotation speeds of n = 300 rpm and n = 720 rpm. Moreover, PVDF-CB double layer is well formed with the increase of n. Furthermore, with the increase of t, the particle size of LiCoO2 coated by CB is slightly changed in the low rotation speeds of n = 50 rpm and of n = 150 rpm; however, the particle size of LiCoO2 coated by CB is increased in the high rotation speeds of n = 300 rpm and n = 720 rpm. The above-mentioned morphological structure characterizations are in agreement with those observed from morphological images of LIB slurry.