Mg-doped layered vanadates for high-energy zinc anode-based electrochromic devices

Zinc anode-based electrochromic devices (ZECDs) demonstrate promising prospects in dual-functional electrochromic (EC)-energy storage systems due to their unique optical and energy retrieval properties. Vanadates are widely used in ZECDs due to their diverse color properties, but their cycling stability and kinetics are often hindered by the strong electrostatic interactions between Zn²⁺ ions and the host vanadate lattice. In this study, we fabricated magnesium ion-doped layered vanadates (MVO) with effectively enlarged interlayer spacing, promoting rapid insertion/extraction of Zn²⁺. Compared to undoped ammonium vanadate (VO), the MVO electrode exhibits superior electrochemical capacity (57.6 mAh m^-2), faster switching kinetics (<i>t</i>_c = 79.6 s, <i>t</i>_b = 25.2 s), enhanced coloration efficiency, and excellent electrochemical reversibility. Finally, the fabricated ZECDs employing MVO films demonstrate exceptional electrochemical reversibility, promising optical switching performance and excellent cycling stability (500 cycles). These results validate the effectiveness of the Mg-doping strategy for the modification of layered vanadates for optimized ZECDs coupling EC and energy storage functionalities.