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 elec trolytes and cathode materials for lithium batteries. In this study, t he 4-volt cathode material LiCoO2 was chosen, and prepared by spraying alcohol solutions of nitrates and acetates of cobalt. ESD set-ups, wi th 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 m easured with Galvanostatic Intermittent Titration Technique (GITT), va lues range from 10(-14) to 10(-12) cm(2)/s, depending on the lithium c ontent and the annealing temperatures. Cyclic Voltammograms of a test cell reveal that both lithium insertion and extraction are one-step pr ocesses.