Boosting the Self-Recharging of Polypyrrole/Prussian Blue Electrochromic Device by Potential Difference-Driven Alternative Redox

Energy-storage electrochromic (EC) devices are a kind of recently developed device integrating energy-saving and energy-storage functions. To minimize energy consumption, a self-rechargeable energy-storage EC device with fast recovery speed is highly desired. Herein, a polypyrrole (PPy)/Prussian blue (PB) double-layer film with a potential difference is initially constructed and fabricated into a fast-recovery self-rechargeable EC device. Due to the existence of potential difference, the reduced PPy can be oxidized by PB, and subsequently Prussian white (the reduced state of PB) can be oxidized by O2 dissolved in electrolyte. Thus, the self-coloration/self-recharging process can be boosted by an alternative redox occurring in the solid/solid/liquid interfaces of PPy/PB/dissolved O2 instead of common solid/liquid interfaces or solutions. After self-recharging for 1 h, 65.0% of the open-circuit voltage and 45.2% of the total capacity can be recovered. Simultaneously, the synergy effect in this PPy and PB system enables a large optical modulation of 63.3% at 800 nm, a high open-circuit voltage of 1.20 V, and a large initial specific capacity of 87.8 mA·h·g–1 at 1.0 A·g–1. The design of double-layer film with a potential difference for boosting the self-coloration/self-recharging process of EC devices provides a new strategy for next-generation self-powered energy-storage EC devices.