Enhanced stability of electrochromic devices based on Prussian blue by tuning electrolyte ions and charge/discharge balance

Electrochromic devices based on intercalation/deintercalation of electrolyte ions as well as charge-balancing electrons, normally are subjected to the deterioration in electrochromic performance due to irreversible reactions between active electrodes and electrolyte species and overvoltage at the electrode/electrolyte interface. Therefore, understanding the independent impact of individual species present at electrode/electrolyte interfaces can optimize reaction performance in electrochemical systems. After thorough scrutiny of the operational devices composed of Prussian blue as an electrochromic layer and zinc oxide nanowire as an ion storage layer, three criteria were taken into consideration for drastically extending the durability of electrochromic devices (i) the substitution of K+ by Na+ or Li+ ions leads to Prussian blue film degradation, (ii) anions with strong adsorption property cause detrimental effect on Prussian blue films, and (iii) charge balance control in/out of Prusisan blue films greatly enhanced the stability of electrochromic devices. We expect that the results provide more insight into the electrochromic degradation and offer great prospects for both academia and industry.