Coordination modulation of hydrated zinc ions to enhance redox reversibility of zinc batteries

Abstract

The dendrite growth of zinc and the side reactions including hydrogen evolution often degrade performances of zinc-based batteries. These issues are closely related to the desolvation process of hydrated zinc ions. Here we show that the efficient regulation on the solvation structure and chemical properties of hydrated zinc ions can be achieved by adjusting the coordination micro-environment with zinc phenolsulfonate and tetrabutylammonium 4-toluenesulfonate as a family of electrolytes. The theoretical understanding and in-situ spectroscopy analysis revealed that the favorable coordination of conjugated anions involved in hydrogn bond network minimizes the activate water molecules of hydrated zinc ion, thus improving the zinc/electrolyte interface stability to suppress the dendrite growth and side reactions. With the reversibly cycling of zinc electrode over 2000 h with a low overpotential of 17.7 mV, the full battery with polyaniline cathode demonstrated the impressive cycling stability for 10000 cycles. This work provides inspiring fundamental principles to design advanced electrolytes under the dual contributions of solvation modulation and interface regulation for high-performing zinc-based batteries and others.

Tetraphenylporphyrin‐based Chelating Ligand Additive as a Molecular Sieving Interfacial Barrier toward Durable Aqueous Zinc Metal Batteries

“…NMR spectra were conducted to investigate the “molecular sieve‐like” interfacial barrier effect of TPPS. As presented in the left panel of Figure 2b, the 1 H peak of ZnSO 4 in D 2 O located at 4.71 ppm shifted to 4.73 ppm after TPPS addition, indicating the destruction of H‐bonds between free H 2 O molecules and the enhanced de‐shielding effect of Zn atom [7c] . Additionally, TPPS proton signals moved to higher field in TPPS/ZnSO 4 electrolyte (the right panel of Figure 2b), which is derived from the electron‐withdrawing effect induced by the interaction between TPPS molecule and Zn 2+ [4,15,21] .…”

An artificial bridge between the anode and the anolyte enabled by an organic ligand for sustainable zinc-based flow batteries

“…Organic additives are commonly employed in zinc-ion batteries. 22,23,29,30 In this work, EDTA with different concentrations (0, 0.1 mol L −1 , 0.3 mol L −1 , and 0.7 mol L −1 , which are denoted as Blank, 0.1 EDTA, 0.3 EDTA, and 0.7 EDTA, respectively) was employed as the anolyte additive to create an artificial bridge between the anode and anolyte for alkaline zinc–iron flow batteries mainly due to the good chemical stability of EDTA in alkaline media. Compared with the battery using the blank anolyte, the addition of EDTA in anolyte has no significant influence on battery efficiency (Fig.…”

Tailoring the Solvation Environment Enables Dendrite-Free Zn Anodes for Stable Zinc-Ion Batteries

“…Owing to their advantages of low cost, safety, high capacity (820 mAh g –1 ), and good compatibility with the environment, aqueous zinc-ion batteries (AZIBs) have become attractive in large-scale sustainable energy storage systems. − On the other hand, dendrite and parasitic reactions involving surface passivation and gas evolution (HER/OER) could cause poor cyclability and Coulombic efficiency (CE) of AZIBs, ultimately contributing to their failure. − In aqueous electrolytes, Zn ions steadily exist in the [Zn­(H 2 O) 6 ] 2+ solvation structure with high desolvation energy barrier and uncontrolled random diffusion, thus leading to chaotic Zn 2+ deposition to form loose and scabrous Zn deposits. , The loosely deposited Zn would generate electronic insulation and sacrifice the reversibility of the battery. Furthermore, the water molecules in Zn 2+ -solvated shell ([Zn­(H 2 O) 6 ] 2+ ) with high chemical activity could easily decompose during the Zn deposition process, forming the passivation byproducts of Zn 4 SO 4 (OH) 6 · x H 2 O. , In this sense, changing the solvation structure with less active water is effective toward dendrite alleviation.…”