High-performance all-solid-state electrochromic asymmetric Zn-ion supercapacitors for visualization of energy storage devices

Abstract

Electrochromic Zn-ion supercapacitors (EZSCs) integrate energy storage and electrochromic function into one platform, providing promising potential for intelligent visualization of energy storage devices. A challenge for the practical applications of EZSCs is to explore electrodes with ultra-robust properties that suppress performance deterioration and irreversible structural damage after ultralong-term electrochemical testing even in a wide temperature environment. Here, a monoclinic WO₃ electrode presents ultralong cycle stability (over 15 000 cycles) and superb optical modulation (up to 72.5%). Notably, the first-principles calculations and experimental results reveal that the ultralong stability stems from the ultra-robust monoclinic structure, and surface capacitance-controlled and fast kinetic behaviours. Furthermore, a novel all-solid-state electrochromic asymmetric Zn-ion supercapacitor (EAZS) is successfully assembled by matching electrochromic electrodes (MnO₂/WO₃). The EAZS delivers a wide voltage window (2 V), high energy/power density (1.25 W h cm⁻³/7.02 W cm⁻³), superb colouring efficiency (89.5 cm² C⁻¹) and especially ultralong cycle life (over 12 000 cycles). Notably, the EAZS also shows remarkable durability and long-term cycling stability over a wide temperature range from 15 to 70 °C. We imagine that this work can provide a novel avenue to construct smart energy storage systems for future portable electronic devices and fast-charging green electric-buses.