Highly porous spongelike ceramic films with bimodal pore structure prepared by electrostatic spray deposition technique

With a high feeding rate of the precursor solution, highly porous spongelike lithium-cobalt-oxide films with bimodal pore structure and porosity over 90% were fabricated at 235 degrees C by the electrostatic spray deposition (ESD) technique. The metal acetates were used as the precursors dissolved in a mixed solvent of ethanol and butyl carbitol. Scanning electron microscopy (SEM) and X-ray diffraction were used to analyze the structure of the as-deposited films. The growth rate was found to be 7.8 mu m/h and 0.24 mg/(cm(2) h). At a relatively long deposition time, this bimodal porous structure may evolve into a porous columnar structure. Other morphologies such as flattened reticular structure and rather dense structure can be obtained at deposition temperatures between 270 and 320 degrees C.