A priori evaluation of the printability of water-based anode dispersions in inkjet printing

Inkjet printing represents a disruptive additive manufacturing technology that has emerged as an innovative approach to generate customized lithium-ion batteries by tailored dispersions. However, electrode dispersions cause a complex non-Newtonian behavior which hampers the processability. This paper demonstrates a novel procedure for an a priori evaluation of the printability of aqueous graphite dispersions. Therefore, dispersions with a varying active material content were prepared and the printability was examined through a characterization of the drop formation and the drop deposition behavior. While the drop formation was observed by in-situ monitoring, the drop deposition was analyzed in ex-situ test setups. The rheological properties were systematically determined to calculate nondimensional numbers that describe the dispensing behavior. Consequently, their capability to predict the stability of the drop formation was evaluated. The results revealed that a graphite dispersion with a content of 2 m% allowed for a stable drop formation. No splashing occurred on the substrate during the drop deposition and sufficient wetting can be assumed due to a contact angle of below 90 ^∘ . Conclusions were drawn to further enhance the active material content. Due to the universality of the proposed approach, it is expected to be applicable to different dispersion systems.