Water‐Based Paintable LiCoO₂ Microelectrodes: A High‐Rate Li‐Ion Battery Free of Conductive and Binder Additives

Abstract A simple, low‐cost, and environmentally friendly water‐based colloidal spray‐painting process is developed to obtain mechanically stable microelectrodes of pure LiCoO₂ on stainless steel disks, which display reversible high‐rate discharge capacity and good cyclability. By using a simple nanostructuring process with commercially available LiCoO₂, the use of dispersant, conductive, and binder additives during the electrode preparation is completely avoided. The nanostructuring approach is based on: i) planetary ball milling and annealing of LiCoO₂ microparticles and ii) LiCoO₂ surface modification through dissociative H₂O adsorption during contact with air‐ and water‐based colloid preparation. The coating technique involves: i) water‐based colloid preparation, ii) spray‐coating, and iii) post‐treatment (drying and calcination) processes. The effects of particle size distribution, shape, crystallinity, specific surface area, and LiCoO₂ surface modification on the electrode architecture (roughness, thickness, packing density, and porosity) are studied, together with their impact on the final electrochemical performances of batteries assembled with such a LiCoO₂ electrode.