Gradient Electrolyte Strategy Achieving Long-life Zinc Anodes.

Aqueous Zn-ion batteries are plagued by a short lifespan caused by localized dendrites. The high-concentration electrolytes are favorable for dense Zn deposition but have poor performance in batteries with glass fiber separators. In contrast, the low-concentration electrolytes can wet the separators well, ensuring the migration of zinc ions, but the dendrites grow rapidly. In this work, we propose an electrolyte gradient strategy that constructs a gradient of zinc ion concentration from anode to separator, ensuring that the separator keeps a good wettability in low-concentration areas and the zinc anode achieves dendrite-free in a high concentration areas. By using this strategy in the common zinc sulfate electrolyte, Zn||Zn symmetric cell achieved 14000 ultra-long cycles (exceed 8 months) at 5 mA cm -2 and 1 mAh cm -2 . When the current was further increased to 20 mA cm -2 , the symmetric cell could still run exceed 10000 cycles. Assembled Zn||NVO full cells also demonstrate prominent performance. At a high current of 16 mA cm -2 , the NVO cathode with high loading (8 mg cm -2 ) still has a capacity of 58% after 1200 cycles. Overall, the gradient electrolyte strategy provides a promising approach for practical long-life Zn anodes with the advantages of simple operation and low cost. This article is protected by copyright. All rights reserved.