The Effect of Different Mixing Processes on the Ionic and Electronic Conductivities of Li-Ion Battery Electrodes

Abstract

In addition to the characteristics of the materials that make up the electrode (such as active material and additives) and the ratios in which the materials are combined, the electrode fabrication process itself plays an important role in the cell performance. This is because the fabrication process is a contributing factor in determining the distribution of particles and the microstructure of the electrode. The first step to making a uniform electrode structure is making a well-mixed slurry. Generally it is believed that too obtain a reliable, high quality electrode, it is essential to avoid agglomeration of the active materials and conductive additives since agglomeration could result in poor transport behavior in the electrode. Highly energetic mixing has been observed to improve cell performance in some cases [1]. In this work, the effect of mixing processes on the microstructure of porous Li-ion battery electrodes is studied through directly measuring electrode tortuosity and local electronic conductivity. Different types of mixing processes were performed by varying, for instance, the speed of mixing. For measuring tortuosity the blocking electrolyte method is used [2]. This method is based on an AC-impedance measurement of the electrode sample using a non-intercalating or blocking electrolyte. For electronic conductivity measurements, a flexible surface conductivity probe was used [3] This research was funded by the BMR program of the US Department of Energy. [1] Dreger et al., 326, PRiME 2016, Honolulu, HI. [2] Landesfeind et al., J. Electrochem. Soc. 163, A1373, (2016). [3] Hardy et al., 113, 231st Meeting of the Electrochemical Society, New Orleans, LA, (2017)