A Kinetically Controlled Biphasic Cu-Zn Alloy Passivated Anode via Green Laser Activatable Alloying of Monolayered Cu Nanoparticles for Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) have emerged as a promising alternative to lithium-ion batteries due to their inherent safety, cost-effectiveness, and environmental friendliness. However, the performance and longevity of ZIBs are often hampered by issues such as a dendrite growth and undesirable side reactions at the zinc (Zn) metal anode. A development of effective passivation layers is prerequisite to address these challenges. In this study, we introduce a novel laser irradiation alloying method to form a thin Cu-Zn alloy passivation layer on the surface of Zn metal anodes. This innovative method overcomes the limitations of conventional thermal processes, which typically produce thick layers that impede ion transfer and increase internal resistance. By employing ultrafast laser irradiation technique, we achieve a precise control on composition and crystalline structure, resulting in a heterogeneous surface layer composed of Cu-rich and Zn-rich biphasic alloys.<br/>Our laser irradiation method offers several advantages. It significantly regulates a photothermally driven diffusion reaction, minimizing the oxidation reaction of monolayered copper nanoparticles, which facilitates the formation of a thin bipahsic Cu-Zn alloy passivation layer with a suitable surface topology. This improved surface characteristic enhances the wettability and hydrophilicity of the Zn anode, which in turn boosts Zn ion affinity at the electrolyte interface, effectively suppressing both of dendrite growth and by-product formation.<br/>The effectiveness of our method is demonstrated with an excellent cycling stability as long as 500 hr at a current density of 10 mA cm^-2 and an areal capacity of 10 mAh cm^-2. The laser irradiation technique represents a scalable, cost-effective solution for high-performance Zn anodes in ZIBs, ensuring longer battery life and greater efficiency. It paves the way for offering a compelling alternative to more expensive and complex techniques of depositing the passivation layer for Zn metal anodes.