Simultaneously Tailoring Zinc Deposition and Solvation Structure by Electrolyte Additive

Long cycle life aqueous zinc-ion battery enabled by a ZIF-N protective layer with electron-withdrawing group and zincophilicity on the Zn anode

Aqueous zinc-ion batteries (AZIBs) have garnered attention from researchers for their high theoretical capacity, safety, and low cost. However, the uncontrolled growth of zinc (Zn) dendrites and spontaneous corrosion reactions on the Zn anode significantly compromise the cycle life of AZIBs. This paper proposes the utilization of a novel zeolitic imidazole framework (ZIF-N) material with zincophilicity and hydrophilicity for modifying the Zn anode of AZIBs. ZIF-N incorporates numerous electron-withdrawing nitro groups at the Zn/ZIF-N interface to regulate the uneven electron distribution on the Zn anode. The modified Zn anode (Zn@ZIF-N) exhibits a lower polarization ratio (32.18 mV at 4 mA cm-2) and an extended cycle life (over 700 h at 4 mA cm-2). At a current density of 1 mA cm-2, the battery composed of a Zn@ZIF-N anode and NVO (NaV3O8) achieves a cycle life of 1600 cycles. This work provides a straightforward and cost-effective strategy for modifying the Zn anode to prolong the cycle life of AZIBs.

Suppressing hydrogen evolution and promoting dendrite free zinc deposition by fluorinated triazine framework towards robust aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have become a research hotspot, but the inevitable zinc dendrites and parasitic reactions in the zinc anode seriously hinder their further development. In this study, three covalent triazine frameworks (DCPY-CTF, CTF-1 and FCTF) have been synthesized and used as artificial protective coatings, in which the fluorinated triazine framework (FCTF) increases the zinc-philic site, thus better promoting dendritic free zinc deposition and inhibiting hydrogen evolution reactions. Excitingly, both experimental results and theoretical calculations indicate that the FCTF interface adjusts the deposition of Zn2+ along the (002) plane, effectively alleviating the formation of zinc dendrites. As expected, Zn@FCTF symmetric cells exhibit cycling stability of over 4000 h (0.25 mA cm-2), meanwhile Zn@FCTF//NHVO full cells provide a high specific capacity of 280 mAh/g at 1.0 A/g, which are superior to those of bare Zn anode. This work provides new insights for suppressing hydrogen evolution and promoting dendrite-free zinc deposition to construct highly stable and reversible AZIBs.

Multifunctionalized Supramolecular Cyclodextrin Additives Boosting the Durability of Aqueous Zinc-Ion Batteries

The poor cycling stability of aqueous zinc-ion batteries hinders their application in large-scale energy storage due to uncontrollable dendrite growth and harmful hydrogen evolution reactions. Here, we designed and synthesized an electrolyte additive, N-methylimidazolium-β-cyclodextrin p-toluenesulfonate (NMI-CDOTS). The cations of NMI-CD+ are more easily adsorbed on the abrupt Zn surface to regulate the deposition of Zn2+ and reduce dendrite generation under the combined action of the unique cavity structure with abundant hydroxyl groups and the electrostatic force. Meanwhile, p-toluenesulfonate (OTS-) is able to change the Zn2+ solvation structure and suppress the hydrogen evolution reaction by the strong interaction of Zn2+ and OTS-. Benefiting from the synergistic role of NMI-CD+ and OTS-, the Zn||Zn symmetric cell exhibits superior cycling performance as high as 3800 h under 1 mA cm-2 and 1 mA h cm-2. The Zn||V2O5 full battery also shows a high specific capacity (198.3 mA h g-1) under 2.0 A g-1 even after 1500 cycles, and its Coulomb efficiency is nearly 100% during the charging and discharging procedure. These multifunctional composite strategies open up possibilities for the commercial application of aqueous zinc-ion batteries.