Construction of a 3D “Onion-like” Model of Conductive Carbon Black for Lithium-Ion Batteries and Exploration of the Electrochemical Oxidation Mechanism of CB and Ethylene Carbonate via ReaxFF MD

The structural characteristics of conductive carbon black (CB) were explored via high-resolution transmission electron microscopy (HRTEM), XRD, Raman spectroscopy, and XPS experimental detection. The CB lattice length of fringes was mostly < 20 Å, and the peak value was approximately 10 Å. The fringes were evenly distributed at 0–360°, consistent with its "onion-like" structure. In total, 2–5 layers were stacked, and the average number of stacks was 2.91, which had a certain order. The proportion of the total length of bending stripes was 67.13%, higher than that of the total number (46.57%), indicating that the bending stripes were generally longer. Then, the onion-like particle model of CB (C11854) was constructed, and the rationality of the model was verified by FT-IR and XRD spectral calculation. Finally, the electrochemical oxidation behavior of CB and ethylene carbonate (EC) in lithium-ion batteries was investigated using reactive force field molecular dynamics (ReaxFF MD) simulation methods. EC attacked CB through the intraring and out-of-ring O, and the decomposition of EC produced CO2 and C2H4. Various O groups were formed on the CB surface, and the destruction of EC and CB affected the cycle stability and life of the batteries. After using F2 as protection for CB, the consumption of EC decreased, and only a few O groups were formed on the CB surface. This result provides high-precision simulation support for slowing down the electrochemical side reactions between CB and EC.