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°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 μm/h and 0.24 mg/(cm2 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°C.