Batteries are key components of portable electric devices. Electrochromic batteries enable the direct readout of a battery’s energy levels through a real-time color change. However, the field is still rather young and many unsolved problems exist, such as a low energy storage capacity and a time-consuming charging process.

Zhigang Zhao, Suzhou Institute of Nano-Tech and Nano-Bionics, China, and colleagues have successfully developed a high-capacity electrochromic battery. Two common materials, aluminum metal and tungsten oxide (W₁₈O₄₉), were selected to construct the electrochromic battery. The device shows many advantages over its traditional counterparts, including a distinguishable color change corresponding to different charge levels.

The electrochromic battery also exhibits a high capacity, as well as fast charging within 8 seconds after the addition of a small amount of hydrogen peroxide. This study may serve as a starting point for the future rational design of new high-performance electrochromic batteries.

• Trace H₂O₂-Assisted High-Capacity Tungsten Oxide Electrochromic Batteries with Ultrafast Charging in Seconds,
  Jinxiong Zhao, Yuyu Tian, Zhen Wang, Shan Cong, Di Zhou, Qingzhu Zhang, Mei Yang, Weikun Zhang, Fengxia Geng, Zhigang Zhao,
  Angew. Chem. Int. Ed. 2016.
  DOI: 10.1002/anie.201602657