Reconstructing the Anode Interface and Solvation Shell for Reversible Zinc Anodes

Abstract

The attractive advantages of the Zn metal anode and water-based electrolyte, such as inherent safety and low cost, endow the zinc-ion batteries (ZIBs) with great potential in the future energy storage market. However, the severe surface side reactions and dendrites affect the service lifespan and electrochemical performance of ZIBs. Herein, a bifunctional electrolyte additive, L-ascorbic acid sodium (LAA), has been added into ZnSO 4 (ZSO) electrolyte (ZSO + LAA) to settle the above issues of ZIBs. On the one hand, the LAA additive tends to adsorb on the Zn anode surface to generate a H 2 O-resistive passivation layer, which can effectively isolate the H 2 O corrosion and regulate the Zn 2+ ion 3D diffusion, thus inducing a uniform deposition layer. On the other hand, the strong adsorption capacity between LAA and Zn 2+ can transform the solvated [Zn(H 2 O) 6 ] 2+ into [Zn(H 2 O) 4 LAA], thus reducing the coordinated H 2 O molecules and further suppressing side reactions. With this synergy effect, the Zn/Zn symmetric battery with the ZSO + LAA electrolyte can deliver a cycle life of 1200 h under 1 mA cm −2 , and the Zn/Ti battery also presents an ultrahigh Coulombic efficiency of 99.16% under 1 mA cm −2 , greatly superior to the batteries with the ZSO electrolyte. Additionally, the effectiveness of the LAA additive can be further verified in the Zn/MnO 2 full battery and pouch cell.

Low-Cost Electrolyte Additive Enables an Ultra-stable and Dendrite-Free Zn Anode

“…First, Fourier transform infrared spectroscopy (FTIR) of various aqueous electrolytes was conducted, and the existence of δ(C–H) appearing at 1380 cm –1 demonstrated the successful introduction of the Ga additive (Figure a) . In addition, the characteristic peak of ν(SO 4 2– ) is observed to be blue-shifted [the characteristic peaks of ν(SO 4 2– ) of ZSO and ZSO–0.5Ga are 1082.03 and 1082.16 cm –1 , respectively; Figure S1 of the Supporting Information], which can be related to the weakened electrostatic coupling between Zn 2+ and SO 4 2– after the Ga additive, indicating that the solvation shell of Zn 2+ is regulated . Second, Raman spectroscopy of the ZSO and additive-containing electrolytes has been performed.…”

“…(h) Voltage–time curves of the Zn||Zn battery with two electrolytes at 0 °C. (i) Cycling performance comparison of Ga and previously reported additives for Zn–Zn symmetric batteries (glucose, dimethyl ether, l -ascorbic acid sodium, diethyl ether, ZnF 2 , sorbitol, ZnNO 3 , and acetonitrile).…”

“…Electrochemical energy storage plays an important role in sustainable energy storage. Lithium-ion batteries with high energy density and power density are used as power sources for various mobile devices and electric vehicles. − However, flammable electrolytes and dwindling lithium resources limit the application of lithium-ion batteries in large-scale energy storage devices. − For the future generation of energy storage devices, aqueous batteries have a superior development path because of their high level of safety. − A standout among the water-based batteries among them is the zinc-ion capacitors (ZICs), because of their high theoretical specific capacity and affordable raw materials. − However, the cycle stability of ZICs is hampered by the flaws of the zinc metal anode, such as poor coulombic efficiency (CE) and Zn dendrites during cycling. − The harmful side reactions, such as the hydrogen evolution reaction (HER), byproducts, and corrosion are ascribed to the higher activity of desolvated water molecules in hydrated Zn 2+ near the Zn surface. − The zinc protrusions or dendrites are caused by the uncontrollable Zn 2+ ion diffusion along the Zn anode. − …”

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

“…Nevertheless, unbounded dendrite growth, corrosion and passivation of zinc (Zn) metal anodes, resulting in low coulombic efficiency (CE) and limited lifetime, which may lead to battery short circuit, is one of the most crucial obstacles for the development of aqueous ZIBs [6–12] . Several strategies have been executed to enhance the electrochemical stability of Zn metal anodes by inhibiting the dendrite formation and banishing the water‐induced parasitic reaction, including electrolyte regulation, interfacial manipulation, substrate modification, etc [13–26] . Among these strategies, electrolyte formulation plays a vital role in regulating the Zn deposition behavior and diminishing the side reaction on Zn metal anodes, because of its effectiveness, simple procedure, and easy implementation [27–29] …”

“…[6][7][8][9][10][11][12] Several strategies have been executed to enhance the electrochemical stability of Zn metal anodes by inhibiting the dendrite formation and banishing the water-induced parasitic reaction, including electrolyte regulation, interfacial manipulation, substrate modification, etc. [13][14][15][16][17][18][19][20][21][22][23][24][25][26] Among these strategies, electrolyte formulation plays a vital role in regulating the Zn deposition behavior and diminishing the side reaction on Zn metal anodes, because of its effectiveness, simple procedure, and easy implementation. [27][28][29] Usually, Zn dendrite growth involves reduplicative processes of nucleation and deposition/dissolution.…”