Spray printing of self-assembled porous structures for high power battery electrodes

A novel, generic methodology to manufacture hierarchically porous electrode structures directly onto current collectors has been developed based on layer-by-layer spray printing, here exemplified using TiO2(B) nanotubes for lithium-ion batteries. By optimizing and then exploiting the bi-solvent drying behavior of the spray printed ink to trigger self-assembly of the active TiO2(B) into a coral-like structure, controlled through-thickness pore channels were created, which were shown to promote lithium-ion mobility throughout the electrode. Using these optimized structures, the electrode thickness-dependent performance of TiO2(B) electrodes at high charge/discharge rates was compared with conventional slurry cast electrodes and revealed the superiority of the self-assembled electrodes, especially at the highest discharge rates. We also show this self-assembly effect in other active materials and over large areas, suggesting the potential for wide use of this approach for electrodes where fast dynamic response is prioritized.