Characterizing the Surface Free Energy of Composite Electrodes for Li-Ion Batteries

Abstract

One of the crucial steps in battery manufacturing is the electrolyte wetting step which typically requires a relatively long time to be completed. It is known that the relationship between polar and dispersive components of the electrolyte surface tension and the electrode surface free energy (SFE) plays a vital role in the extent of wetting and, thus, tuning the SFE can accelerate the wetting step in battery manufacturing. This work developed and validated a systematic approach to characterize surface free energy of composite electrodes for lithium-ion batteries, which has never been reported in literature. It’s demonstrated as shown in Figure 1 [1] that the SFE of LiNi0.5Mn0.3Co0.2O2 cathode was higher than the graphite anode. In addition, when switching manufacturing from conventional solvent based processing to aqueous processing, the polar component of SFE increases; it increases 74.1% from NMC532-NMP to NMC532-Water, and 48.2% from A12-NMP to A12-Water due to different binders. SFE decreases with reducing porosity. The results provide valuable guidance for our goal to optimize the electrolyte wetting process, helping lower costs and enable higher product quality. In addition, the method allows us to characterize the SFE of electrodes and optimize electrolyte wetting via tailored electrode manufacturing, including slurry and electrode formulation, mixing sequences, drying protocols and calendering. Figure 1 Surface energy of electrodes Reference: [1] A. Davoodabadi, J. Li, Y. Liang, R. Wang, H. Zhou, D.L. Wood III, T. J. Singler, and C. Jin, Journal of the Electrochemical Society, 165(11) (2018) A2493-A2501 Figure 1