Plasma-engineered CuOx with Cu+ /Cu2+ states and oxygen vacancies for flexible zinc-air batteries

Flexible zinc-air batteries (FZABs) hold great promise for powering next-generation wearable electronics, yet their advancement is hindered by sluggish oxygen electrocatalysis and poor cycling stability. Here, we employ a dielectric barrier discharge (DBD) plasma-assisted approach to modify CuO x /activated carbon (CuO x /AC) composite catalysts, offering a facile and scalable route to simultaneously tailor surface chemistry and nanostructure. The plasma treatment generates abundant oxygen vacancies and stabilizes mixed Cu + /Cu 2+ valence states, thereby accelerating both oxygen reduction and evolution reaction (ORR/OER) kinetics. It also produces a three-dimensional porous architecture of vertically aligned nanosheets with uniformly dispersed CuO x nanoparticles, enabling rapid electron/mass transport. When applied in FZABs, the CuO x /AC-DBD catalyst achieves a high peak power density (226 mW cm −2 ), an open-circuit voltage of 1.37 V, and remarkable cycling stability with 95% capacity retention. Compared with untreated catalysts, it exhibits a much lower charge-transfer resistance (12 Ω cm 2 ) and superior durability. This study demonstrates that DBD plasma engineering is an effective and low-cost strategy for designing high-performance bifunctional catalysts, paving the way for flexible and wearable energy storage devices.