Recently, Professor Xingbo Liu's research group at West Virginia University and Xiaolin Li et al. from Pacific Northwest National Laboratory published an important article in *Nano Energy*, titled "Polyvinyl Alcohol Coating Induced Preferred Crystallographic Orientation in Aqueous Zinc Battery Anodes".
The development of rechargeable aqueous zinc batteries has been mainly hindered by the zinc anode, which suffers from problems such as dendrite growth, corrosion, hydrogen evolution, and surface passivation. Here, a thin polyvinyl alcohol (PVA) coating on the zinc anode effectively regulates interfacial ion diffusion and induces uniform zinc nucleation and deposition in a stack with a preferred crystal orientation (002), making dendrite-free, long-life aqueous zinc batteries possible.
The PVA@Zn anode achieved an ultra-long cycle life of thousands of hours at 0.25 and 1 mA cm⁻². Excellent durability was achieved under conditions of deep cycle capacity (5 mAh cm⁻²), high current density (10 mA cm⁻²), and long duration. The excellent cycleability of the PVA@Zn anode was also demonstrated in PVA@Zn//V₂O₅ full cells. Insights into PVA-induced Zn deposition with preferred crystal orientation and interface modulation provide inspiration for the future development of stable Zn anodes.
The authors developed a highly stable and dendrite-free Zn anode using a simple PVA coating method. The PVA@Zn anode exhibited long-term cycling stability exceeding 5000 hours in symmetric cells at 0.25 mA cm⁻² and 0.25 mAh cm⁻². Even at a deep cycling capacity of 5 mAh cm⁻², the developed PVA@Zn anode exhibited excellent durability exceeding 2600 hours, maintaining significant cycling stability even at a high current density of 10 mA cm⁻².
The PVA coating induced uniform Zn nucleation, epitaxial growth, and stacked deposition with a preferred exposed crystal orientation of the (002)Zn plane. Furthermore, the PVA protective layer effectively suppresses interfacial side reactions such as HER, corrosion, and surface passivation. The interaction between PVA and hydrated Zn²⁺ influences and plays a crucial role in the Zn²⁺-H₂O-OTf⁻ coordination structure. This study provides a direct method for stabilizing zinc electrochemistry in mild aqueous electrolytes by using low-cost PVA as an artificial interfacial protective layer for high-performance zinc-ion batteries.
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