| The objective of this thesis work is to investigate cathodic battery materials for application as counter-electrode materials for an electrochromic (EC) device known as a "Smart Window".; Electrochromic phenomena and the microscopic basis for electrochromism are reviewed and the principles and structure of electrochromic devices are discussed.; Electronic and structural properties of transition metal oxides are examined with respect to the requirements for an electrochromic counter-electrode material. Some criteria relating the material properties to the device requirements are established. Potential candidate materials were examined, based on these criteria, and lithium cobalt oxide, LiCoO{dollar}sb2{dollar}, was selected for further examination.; The preparation of lithium cobalt oxide thin films, utilizing several different methods, is described. The most useful films for EC device application were prepared by rf sputtering.; The thin films were shown by X-ray diffraction to retain the basic structure of the parent compound. By chemical analysis they show a lithium deficiency corresponding to Li/Co ratios of about 0.5. The films undergo reversible electrochemical removal and insertion of lithium ions, accompanied by significant transmission and reflection modulation, behaving as an anodically coloring EC material. Electronic transport properties show p-type conduction. Several of the measured properties are consistent with a calculated density of states (DOS) diagram. An all-solid-state electrochromic window device utilizing a lithium cobalt oxide counter-electrode was constructed, and exhibited good electrochemical stability and reversibility, as well as showing good mechanical durability. |
