Durability of electrochromic windows fabricated with carbon-based counterelectrode

A tungsten oxide film has been widely employed as an electrochromic material due to its great electrochemical durability. Durability of carbon materials as electrodes have been even more clearly verified in many practical use, a lithium ion battery and an electric double layer capacitor, for example. We then focused on a large electric double layer capacitance and the electrochemical durability in carbon materials. The chief purpose of this paper is to examine electro-optical performance and durability of the electrochromic window (ECW) fabricated with the carbon-based electrode. The ECWs have been tested for durability under various weather conditions. Most of the tests were carried out on the ECWs with UV-cut filters installed. The filters allowed us to improve the ECW durability greatly. Main results are as follows: 1) we were successful in developing carbon-based electrodes for ECWs and in fabricating an ECW (a carbon-based electrode/a polymeric solid electrolyte (PSE)/a tungsten oxide electrode), 2) the utilization of the carbon-based electrode increased the ECW durability against high temperature, UV radiation, heat cycle and so forth, and 3) their electrochromic performance were found out to be sufficiently high enough for architectural and automotive purposes.