Electrostatic spray deposition of thin layers of cathode materials for lithium battery

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 LiCoO2 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, LiCoO2 layers are XRD amorphous. Upon annealing, crystallized layers are obtained. The lithium chemical diffusion coefficient of the LiCoO2 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.