Alignment of Conductive Additive in Li-Ion Battery Electrodes through Use of Electric Fields

Abstract

Currently, Li-ion battery electrodes are produced by coating onto the current collector a slurry composed of active particles, carbon black (CB), binder, and solvent. Coating is followed by drying, and calendering steps. This method creates a quasi-random distribution of CB particles throughout the battery electrode. The CB particles are intended to improve electronic pathways between active particles and the current collector. By applying an electric field to the electrode slurry while it is drying, the carbon particles can be aligned or form chains in response to electric forces. These chains function as improved pathways for the electrons, reducing the impedance of the electrode. This has the potential to allow thicker electrodes, faster charging, or possibly a reduction in the required amount of CB additive. In this talk, we discuss our use of flexible micro-probes [1] to both apply an electric field during drying and to assess the final conductivity of the dried film. Alternating electric current (AC) is used. The impedance of the samples dried with AC will be compared with of those of sample dried using conventional methods. We also explore the effects of different frequencies of AC on the resulting conductivity and discuss the plausibility of scaling this method of drying under electric fields to an industrially relevant process. [1] Lanterman et al., J. Electrochem. Soc. 162, A2145-A2151 (2015).