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

A simple, low‐cost, and environmentally friendly water‐based colloidal spray‐painting process is developed to obtain mechanically stable microelectrodes of pure LiCoO 2 on stainless steel disks, which display reversible high‐rate discharge capacity and good cyclability. By using a simple nanostructuring process with commercially available LiCoO 2 , 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 LiCoO 2 microparticles and ii) LiCoO 2 surface modification through dissociative H 2 O 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 LiCoO 2 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 LiCoO 2 electrode.