Stabilization of Zn anode via a multifunctional cysteine additive

Reconstructing the Anode Interface and Solvation Shell for Reversible Zinc Anodes

“…44 In comparison, the current response of the Zn anode in the ZSO + LAA electrolyte gradually equilibrates 50 s and achieves a fast 3D diffusion behavior on the Zn surface, since the LAA-adsorbed layer on the Zn surface can increase the Zn 2+ diffusion barrier and effectively suppress the 2D diffusion, thus enabling a dendrite-free Zn anode. 17 Further, the solvation process of Zn 2+ in various electrolytes has been investigated, as displayed in Figure 2d , 28 whereas the intensity of these peaks will weaken and shift after introducing the LAA additive, implying that the electrostatic constraint between Zn 2+ and SO 4 2− is weakened, which can be ascribed to the regulated Zn 2+ solvation structure. 45 In addition, the nuclear magnetic resonance (NMR) spectra of pure D 2 O and LAA solution show that the same 2 H lies in 4.634 ppm (Figure 2e), and the 2 H NMR peak of the pure ZSO electrolyte is located at 4.691 ppm.…”

“…As for the side reactions, the anode corrosion has been monitored via the linear polarization (Tafel) plots (Figure a), the electrode in the ZSO electrolyte delivers a much lower corrosion potential of −1.009 V ( vs Ag/AgCl) than that of the ZSO + LAA electrolyte (−0.974 V), demonstrating a higher corrosion resistance of the Zn anode in ZSO + LAA . In addition, the HER overpotential of Zn electrodes has been tested via linear sweep voltammetry (LSV) (Figure c), where the electrode in the ZSO + LAA electrolyte presents a much higher HER potential (−1.223 V vs Ag/AgCl) than that of the ZSO electrolyte (−1.137 V) at −10 mA cm –2 , suggesting a stronger resistance for HER in the ZSO + LAA electrolyte . Further, the Zn surface passivation in ZSO and ZSO + LAA electrolytes has been investigated via X-ray diffraction (XRD); as depicted in Figure d, the Zn metal anode surface presents a series of newly emerged diffraction peaks after 100 cycles, such as 8.4, 16.5, 24.7, 27.9, and 33.2°, which is corresponding to the byproduct (Zn 4 SO 4 (OH) 6 ·5H 2 O, PDF: 39-0688) .…”

“…49 In addition, the HER overpotential of Zn electrodes has been tested via linear sweep voltammetry (LSV) (Figure 4c), where the electrode in the ZSO + LAA electrolyte presents a much higher HER potential (−1.223 V vs Ag/AgCl) than that of the ZSO electrolyte (−1.137 V) at −10 mA cm −2 , suggesting a stronger resistance for HER in the ZSO + LAA electrolyte. 17 Further, the Zn surface passivation in ZSO and ZSO + LAA electrolytes has been investigated via X-ray diffraction (XRD); as depicted in Figure 4d, the Zn metal anode surface presents a series of newly emerged diffraction peaks after 100 cycles, such as 8.4, 16.5, 24.7, 27.9, and 33.2°, which is corresponding to the byproduct (Zn 4 SO 4 (OH) 6 • 5H 2 O, PDF: 39-0688). 29 And the intensity of these characteristic peaks of Zn 4 SO 4 (OH) 6 •5H 2 O in the Zn/ZSO system is much higher than that in the Zn/ZSO + LAA system, implying that the LAA can effectively inhibit the byproduct.…”

“…First, the redox potential of the Zn metal is lower than that of H 2 O/H 2 and enables a thermodynamic instability in aqueous solution, thus inducing the hydrogen evolution reaction (HER) and poor CE. 17 And the de-solvated dipolar water molecules from the hydrated Zn 2+ possess higher reaction activity when approaching the Zn anode surface, which can easily decompose into hydrogen and induce other side reactions. 18 Second, most of the Zn 2+ ions prefer the spontaneous nucleation and agglomeration via uncontrolled two-dimensional (2D) diffusion along a Zn anode for minimizing the energy, thus forming the protrusions and dendrites on the Zn surface.…”

“…Nevertheless, the practical applications of ZIBs are still hindered by the poor Coulombic efficiency (CE) and severe Zn dendrites, and the above obstacles of ZIBs are ascribed to the following two aspects. First, the redox potential of the Zn metal is lower than that of H 2 O/H 2 and enables a thermodynamic instability in aqueous solution, thus inducing the hydrogen evolution reaction (HER) and poor CE . And the de-solvated dipolar water molecules from the hydrated Zn 2+ possess higher reaction activity when approaching the Zn anode surface, which can easily decompose into hydrogen and induce other side reactions .…”