Critical electrode properties and drying conditions causing component segregation in graphitic anodes for lithium-ion batteries

Among others, the performance of lithium-ion batteries is determined by the structure and material distribution of the electrodes. These electrodes are known to develop an inhomogeneous inactive material distribution during drying of the wet-coated film. The segregation of the conductive additive and the binder was found for the graphite anodes studied in this work and was proven by indirect and direct analyses. Segregation reduces the adhesion strength between coating and substrate and increases the electrical resistance as well as the elasticity of the anode. It was found by spectroscopic analysis that binder concentration and by association carbon black concentration increase from bottom to top of the coating. This Segregation increases with drying temperature and the amount of solvent that needs to evaporate. An auxiliary parameter is introduced to determine a combined, critical value for the driving force of the solvent evaporation (drying temperature) and the anodes’ mass loading. Finally, the mass loading and/or the drying temperature to avoid segregation can be estimated with regard to the final product and the existing drying equipment.