Gradient Electrolyte Strategy Achieving Long‐Life Zinc Anodes

Abstract

Aqueous Zn-ion batteries are plagued by a short lifespan caused by localized dendrites. High-concentration electrolytes are favorable for dense Zn deposition but have poor performance in batteries with glass-fiber separators. In contrast, 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 wherein a zinc-ion concentration gradient is established from the anode to the separator, ensuring that the separator keeps a good wettability in low-concentration areas and the zinc anode achieves dendrite-free deposition in a high-concentration area. By using this strategy in a common electrolyte, zinc sulfate, a Zn||Zn symmetric cell achieves 14 000 ultralong cycles (exceeding 8 months) at 5 mA cm −2 and 1 mAh cm −2 . When the current is further increased to 20 mA cm −2 , the symmetric cell could still run for over 10 000 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.

Reshaping Zinc Plating/Stripping Behavior by Interfacial Water Bonding for High‐Utilization‐Rate Zinc Batteries

“…[14][15][16][17] To solve these issues, controlling the activity of water molecules is crucial. [18,19] Some approaches have tackled water molecules in aqueous electrolytes, including decorating the Zn anode surface with hydrophobic layers to shield it from water, [20][21][22][23] optimizing the composition of aqueous electrolytes to reduce the water activity, [24][25][26][27][28][29][30][31] and fabricating hydrogel electrolytes to confine water molecules within their matrix by hydrogen bonds. [32,33] Fabricating hydrogel electrolytes is regarded as a competitive strategy.…”

Study of a novel supramolecular hydrogel electrolyte for aqueous zinc ion batteries

“…24 Besides, there are also problems in liquid electrolytes, including dissolution of the cathode material, corrosion, passivation and generation of by-products. 25,26 Although the mechanical strength of solid electrolytes is beneficial to inhibit the growth of dendrites and avoid the decomposition of water and the water-induced side effects, 27,28 their low ionic conductivities at low temperature, high interfacial charge-transfer resistances, and poor contact with the electrodes often result in dissatisfactory performance. 29,30 Due to the unique three-dimensional network structure of hydrogels, hydrogel electrolytes combine the merits of liquid and solid electrolytes.…”

Nonflammable Organics/H2O Hybrid Electrolyte with a High Organics Ratio toward Safe and Sustainable Aqueous Na/Zn Hybrid Batteries

“…However, the intermittent and unstable feature of the renewable energy makes it difficult to utilize it directly. Developing large-scale energy-storage systems to store and convert the intermittent energy is critical and necessary for regulating power output and satisfying grid connection. − Because of the risks of resources, price and security, the traditional lithium-ion batteries (LIBs) are not competitive for large-scale energy-storage applications. − Rechargeable aqueous sodium-ion batteries and zinc-ion batteries are regarded as promising candidates for large-scale energy storage because of abundance and low cost of the resources, inherent safety, and environmental friendliness. − Particularly, Daniell-type aqueous Na/Zn-ion hybrid batteries have attracted an increasing attention, where anode can use high-energy-density metallic Zn and cathode can use sodium intercalation materials. − However, cathode dissolution, Zn corrosion and dendrite growth, and hydrogen evolution reactions would hamper their practical applications. − …”