Flexible Zn‐ion Electrochromic Batteries with Multiple‐color Variations

Abstract

Electrochromic batteries as emerging smart energy devices are highly sought after owing to their real-time energy monitoring through visual color conversion. However, their large-scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn-ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VO_Na+) cathode, ion-redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored -SO₃ ^- and -NH₃ ⁺, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn²⁺ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid-charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g^-1 at 0.05 A ⋅ g^-1 with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g^-1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.