Cathode/Anode electrodes for large-area bifunctional electrochemical devices prepared by a novel Na3Cit-assisted chemical deposition method

A Na3Cit-assisted chemical bath deposition (CBD) method was developed to prepare cathode and anode electrodes for large-area electrochromic energy-storage bifunctional electrochemical devices. Prussian blue (PB) and WO3 electrodes with areas greater than 100 cm2 were successfully prepared as the model materials. The PB electrodes exhibit excellent energy-storage and electrochromic properties, including an area capacity of 34.2 mAh/m2, transmittance modulation of 83.0 % at 633 nm, and coloration efficiency of 105.6 cm2/C. The WO3 electrode exhibits reversible optical modulation in both visible and near-infrared (70.8 % at 633 nm, 71.7 % at 1200 nm) and an area capacity of 40.6 mAh/m2. A 10 cm x 10 cm electrochromic energy-storage prototype device was assembled with PB and WO3 electrodes, showing a high area capacity of 34.8 mAh/m2 and transmittance modulation of 60.9 % and 46.9 % at 633 nm and 1200 nm, respectively, which can achieve to coloration, bleaching, and energy supply states. The complexation effects of Na3Cit with precursors ensuring uniformity during the film deposition are discussed in detail. These results not only provide a practicable dualband electrochromic energy-storage bifunctional device but also establish a general strategy to prepare largearea electrodes for high-performance electrochemical devices utilizing wet chemical routes.