Electrochromic zinc-ion batteries: recent progress, challenges and perspectives

The evolution of electrochromic materials and technologies has opened innovative avenues for smart devices. However, their civilian adoption remains constrained by high material costs and energy-intensive fabrication processes. Recent research has shifted toward integrated electrochromic systems that combine energy storage with visualization capabilities. Among these, electrochromic supercapacitors (ECSCs) suffer from relatively low energy density, constraining their storage capacity, whereas electrochromic zinc-ion batteries (ECZIBs) demonstrate superior energy density, making them more promising for smart energy storage applications. This review systematically examines the fundamental structure, key performance parameters, and essential materials of ECZIBs, with particular focus on recent progress in the design of cathode, anode, and electrolyte materials. We summarize the major bottlenecks currently impeding performance enhancement and practical deployment, discuss potential strategies to overcome these challenges, and provide an outlook on future development trends in ECZIBs. We hope this concise review will offer valuable guidance and inspire further research, ultimately fostering new breakthroughs in this emerging field.