Ultra‐Stable Aqueous Zinc Batteries Enabled by β‐Cyclodextrin: Preferred Zinc Deposition and Suppressed Parasitic Reactions

Abstract

The intrinsic zinc dendrite growth aggravated by the uneven electric field at the Zn anode surface and the water‐induced parasitic reactions have largely impeded rechargeable aqueous zinc‐ion batteries for the practical applications in large‐scale energy storage. Here, an effective strategy is proposed to manipulate Zn deposition and simultaneously prevent the generation of insulating by‐products (Zn4SO4(OH)6·xH2O) for improved plating/stripping on Zn anodes by the addition of a nontoxic electrolyte additive, β‐cyclodextrin (β‐CD). The simulation results indicate that β‐CD molecules prefer to adsorb horizontally on Zn (002) plane, regulating the diffusion pathways and deposition sites of Zn2+ for the preferred Zn deposition along (002) plane without dendrite formation and inhibiting the H2 generation and the formation of Zn4SO4(OH)6·xH2O by facilitating desolvation of [Zn(H2O)6]2+. Consequently, an ultra‐long stable cycling up to 1700 h at a high current density of 4 mA cm−2 can be achieved by the addition of β‐CD, 17 times that of the pure ZnSO4 electrolyte and the remarkable stability is also maintained under harsh test condition (40 mA cm−2, 20 mAh cm−2). This study highlights the important role of β‐CD in engineering the interfacial stability during Zn plating/stripping for high‐performing aqueous batteries.

Addition of Dioxane in Electrolyte Promotes (002)-Textured Zinc Growth and Suppressed Side Reactions in Zinc-Ion Batteries

“…The Fourier transform infrared (FTIR) spectrum of Zn foil soaked in DX/water shows two bands at 830.4 and 1043.7 cm –1 corresponding to the vibration of the C–O–C characteristic peaks (Figure b), and the shift of peaks to lower wavenumbers (red shift) is attributed to the interaction between DX and Zn metal. The O atom with high electronegativity in DX coordinates with Zn, which weakens the strength of C–O–C bond, contributing to the red shift of peak position, which is consistent with the Raman results (Figure S4). The characteristic oxygen peaks corresponding to the C–O–C vibrations located at 286.2 and 532.3 eV are observed in the C 1s and O 1s X-ray photoelectron spectroscopy (XPS) spectra (Figures c and S5), showing that the DX exists on the soaked Zn surface.…”

Electrolyte Regulation of Bio‐Inspired Zincophilic Additive toward High‐Performance Dendrite‐Free Aqueous Zinc‐Ion Batteries

“…In addition, the left shift of CV profiles indicates that the Gly additive can weaken the polarization behavior of full cells to a certain extent. [39,50,51] Subsequently, the rate performance for both cells was tested from 0.1 to 4 A g −1 . As displayed in Figure 7c, the full cell with Gly-containing electrolyte has a slightly higher capacity than that using bare ZnSO 4 electrolyte at various current densities.…”

Quasi‐Decoupled Solid–Liquid Hybrid Electrolyte for Highly Reversible Interfacial Reaction in Aqueous Zinc–Manganese Battery

“…This can be used to estimate the zinc deposition morphology according to the relationship between nucleated grain radius and the nucleation overpotential $$\[ \begin{array}{*{20}{c}}{r\; = \;2\frac{{\gamma {V_{\rm{m}}}}}{{F\left| \eta \right|}}}\end{array} \]$$in which the γ is the interface energy, V m is the molar volume of Zn, F is the Faraday constant, and η is the nucleation overpotential. [ 40 ] Compared with the 2+0.1 electrolyte, the CV curve in 2+0.1+KL electrolyte exhibits the more obvious nucleation step with larger nucleation overpotential of ≈0.1 mV, while the overpotential in 2+0.1 electrolyte seems that this can be ignored. Hence, the larger nucleation overpotential represents the more uniform and fine zinc deposition, which is consistent with the relative analysis in Figure 2 and Figure S5 (Supporting Information).…”