Covalent Organic Polymers for Flexible Zinc-Air Batteries: Bridging the Gap Between Three-Electrode Tests and Device Performance

Abstract

Flexible zinc-air batteries (FZABs) offer high theoretical energy density, environmental friendliness, and mechanical flexibility, making them highly promising for wearable and portable electronics. However, a significant gap exists between their actual device performance and three-electrode test results, primarily due to complex multiphase interfacial reactions at the air cathode, poor synergy between intrinsic catalytic activity and mass transport in the catalytic layer, and insufficient interfacial stability in solid-state electrolytes. This review focuses on covalent organic polymers (COPs) as an emerging material platform and systematically explores their critical role in bridging this “test-device” gap. We begin by discussing the synthesis of COPs and the modulation of their intrinsic active sites, highlighting the unique advantages of pyrolysis-free COPs in enhancing catalytic selectivity. Subsequently, we examine the structure-property relationships and performance of COPs in flexible devices, including their applications as catalytic layers, electrolytes, and integrated electrodes. In the context of extreme environments, we evaluate the adaptability and failure mechanisms of COP-based FZABs. Furthermore, we deepen the understanding of air cathode catalytic mechanisms and interfacial processes through theoretical calculations, in situ characterization, and machine learning. Finally, we summarize the current challenges and future directions in material design, device integration, and mechanistic research for COP-based FZABs. This review aims to provide a systematic reference for the rational design and practical advancement of COP materials for FZABs.