Regulating Surface Reaction Kinetics through Ligand Field Effects for Fast and Reversible Aqueous Zinc Batteries

Abstract

Designing water-deficient solvation sheath of Zn 2 + by ligand substitution is a widely used strategy to protect Zn metal anode, yet the intrinsic tradeoff between Zn nucleation/dissolution kinetics and the side hydrogen evolution reaction (HER) remains a huge challenge. Herein, we find boric acid (BA) with moderate ligand field interaction can partially replace H 2 O molecules in the solvation sheath of Zn 2 + , forming a stable water-deficient solvation sheath. It enables fast Zn nucleation/dissolution kinetics and substantially suppressed HER. Crucially, by systematically comparing the ligand field strength and solvation energies between BA and the ever-reported electrolyte additives, we also find that the solvation energy has a strong correlation with Zn nucleation/dissolution kinetics and HER inhibition ability, displaying a classic volcano behavior. The modulation map could provide valuable insights for solvation sheath design of zinc batteries and beyond.

Polycation‐Regulated Electrolyte and Interfacial Electric Fields for Stable Zinc Metal Batteries

“…g) Comparison of cyclic reversibility in the recent reports using the "four-in-one" model. [30,34,35,37,40,43,47,51,56,57,[61][62][63][64][65] Galvanostatic cycling of Zn j j Zn cells in h) 1 M Zn(OTF) 2 -based and i) 1 M Zn(OAc) 2 -based electrolytes with polyelectrolyte additives at 1 mA cm À 2 and 1 mAh cm À 2 .…”

“…Although these small molecule additives are effective in stabilizing the Zn anode, regulating the solvation sheath is ineluctably accompanied by low‐grade Zn 2+ deposition/dissolution kinetics, because of the strong intrinsic coupling between Zn 2+ and additive. Moreover, these additives cannot fundamentally restrain Zn anodes from contacting water owing to the inability to form a high‐quality protective layer in a short time, and some may consume electrons from Zn anodes and be decomposed, which would result in a inferior CE and reversibility [46, 47] . On the other hand, polymers with large skeleton and abundant functional groups are usually used to construct solid polymer electrolytes, quasi‐solid gel electrolytes or functional coatings to improve ion flux and transport, and alleviate the disordered deposition of ions and parasitic reaction [10, 21, 48, 49] .…”

Weakly Solvating Effect Spawning Reliable Interfacial Chemistry for Aqueous Zn/Na Hybrid Batteries

“…Aqueous Zn batteries (AZBs) with mild aqueous electrolytes are proposed as a viable candidate for next-generation energy storage systems considering their responsible safety, high power density, environmental friendliness, as well as high theoretical capacity (820 mAh g −1 , 5855 mAh cm −3 ), and suitable potential −0.76 V (vs SHE, the standard hydrogen electrode) of Zn anode. [1][2][3][4][5][6] The notorious interfacial chemical properties of zinc anode in aqueous electrolytes, including dendrite growth, SEI make them subject to rupture and shedding during the cycle. [17,20] Furthermore, due to pitiably interfacial contact and lack of self-healing ability, such interfaces tend to lose their protective ability blaming the irreversible degradation in the long cycle.…”

“…Aqueous Zn batteries (AZBs) with mild aqueous electrolytes are proposed as a viable candidate for next‐generation energy storage systems considering their responsible safety, high power density, environmental friendliness, as well as high theoretical capacity (820 mAh g −1 , 5855 mAh cm −3 ), and suitable potential −0.76 V (vs SHE, the standard hydrogen electrode) of Zn anode. [ 1–6 ] The notorious interfacial chemical properties of zinc anode in aqueous electrolytes, including dendrite growth, hydrogen evolution reaction (HER), and by‐products accumulation, seriously restrict the reversibility of zinc anode deposition and stripping, which substantially deteriorates the performance of full batteries ( Figure 1 a). [ 7–10 ] Developing attainable and effective strategies to ameliorate the interface chemical properties of zinc anode has become the inevitable course for the further commercial application of AZBs.…”

Inhibition of side reactions and dendrite growth using a low-cost and non-flammable eutectic electrolyte for high-voltage and super-stable zinc hybrid batteries

“…4 However, the Zn anode persistently performs unsatisfactorily in conventional aqueous electrolytes ascribed to severe irreversibility issues. 5 During the Zn battery cycling, it is inevitable that some problems arise, including dendrite growth, irreversible byproduct formation (Zn hydroxides or zincates), and sustained water consumption. [6][7][8] Besides, low coulombic efficiency (CE) of Zn plating/stripping remains a severe challenge which causes the Zn to be oversupplied due to its consumption by the side reactions.…”