Electrostatic spray deposition of thin layers of cathode materials for lithium battery
Abstract A novel fabrication technique, namely electrostatic spray deposition (ESD), has been developed in order to prepare thin layers of solid electrolytes and cathode materials for lithium batteries. In this study, the 4-volt cathode material LiCoO 2 was chosen, and prepared by spraying alcohol solutions of nitrates and acetates of cobalt. ESD set-ups, with either horizontal or vertical configurations, were used. Depending on the precursor and process deposition conditions, the morphology of the layers can be relatively dense, fractal-like porous, or unique 3-D cross-linked porous structures with a high porosity and a narrow pore size distribution. For low deposition temperatures, LiCoO 2 layers are XRD amorphous. Upon annealing, crystallized layers are obtained. The lithium chemical diffusion coefficient of the LiCoO 2 layers has been measured with Galvanostatic Intermittent Titration Technique (GITT), values range from 10 −14 to 10 −12 cm 2 /s, depending on the lithium content and the annealing temperatures. Cyclic voltammograms of a test cell reveal that both lithium insertion and extraction are one-step processes.