Architecture-driven design of ZnO@C anodes in next-generation zinc-based batteries: Toward practical energy storage systems

Zinc-based batteries are promising for sustainable energy storage due to their low cost and environmental friendliness. However, challenges such as passivation, low cycle life, and limited zinc utilization hinder practical commercialization. In this study, we address these challenges using ZnO@C nanoparticles (NPs) as anode active material, optimizing slurry formulation and electrode architectures. PTFE and CMC were employed as complementary binders to enhance mechanical integrity, wettability, and zinc utilization, while reducing the reliance on fluorinated binders. Two electrode fabrication methods — blade coating and hot pressing — were evaluated to assess the effects of active layer thickness on performance and durability. Full-cell Zn/Ni tests were run under harsh testing condition: closed cell, low amount of electrolyte and no additive or ZnO saturation. We found that thinner (ca. 100 μm), blade-coated ZnO@C anodes outperformed thicker (ca. 400 μm) hot-pressed electrodes in both cycle life and specific capacity. Blade-coated electrodes maintained a discharge-specific capacity exceeding 400 mAh g−1for over 200 cycles and achieved a maximum of 524 mAh g−1, approximately 80 % of ZnO theoretical capacity. Post-mortem X-ray computed microtomography analyses revealed that the crucial electrode architecture parameters are ZnO particle accessibility and even utilization in the electrode bulk. These resulted to be optimal in blade-coated electrodes, while heterogeneities and untransformed ZnO volumes were found in the hot-pressed ones. Additionally, in view of concrete device implementation, the often overlooked role of cell casing materials was explicitly addressed. Specifically, the galvanic coupling among electrode material, current collector and cell casing was positively measured and rationalized. By integrating innovations in slurry formulations, electrode design, and practical testing setups, this work provides guidelines to transfer nanostructured Zn anodes to the practical device environment.