Overcoming the Technical Challenges in Al Anode-Based Electrochromic Energy Storage Windows

A new variant of electrochromic energy storage (EES) windows is introduced recently by pairing an electrochromic cathode with an Al anode. Electrochromism in this case is driven by the built-in potential difference and chemical recharging (via oxidation by O-2 or H2O2) without the need for an external power source. However, the Al anode-based EES windows are adversely affected by the irreversibility of the Al anode reaction, the inconvenience of chemical recharging, and a short cycle life. An electrically rechargeable alternative based on a prelithiated Al anode and a WO3-x cathode is presented here, which not only overcomes the operational difficulties of Al anode-based EES windows, but also allows for spectrally selective modulation of visible light and near-infrared and efficient energy recycling. This dual-band electrochromic energy storage (DEES) window upon assembly is able to self-colorize by its high built-in cell voltage (approximate to 2.59 V) without any energy input, and to recycle a large fraction of the energy consumed in the bleaching operation. The DEES window, with its impressive dual-band electrochromic performance and low energy consumption in a round-trip electrochromic operation, can be an energy-saving technology for buildings.