Transparent photovoltaic technologies: Current trends towards upscaling

Rechargeable aqueous zinc (Zn) batteries are promising for large-energy storage because of their low cost, high safety, and environmental compatibility, but their implementation is hindered by the severe irreversibility of Zn metal anodes as exemplified by water-induced side reactions (H2 evolution and Zn corrosion) and dendrite growth. Here, we find that the introduction of a hydrophobic carbonate cosolvent into a dilute aqueous electrolyte exhibits a much stronger ability to address the reversible issues facing Zn anodes than that with hydrophilic ones. Among the typical carbonates (ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate (DEC)), DEC as the most hydrophobic additive enables the strongest breaking of water's H-bond network and replaces the solvating H2O in a Zn2+-solvation sheath, which significantly reduces the water activity and its decomposition. Additionally, DEC molecules preferentially adsorb onto the Zn surface to create an H2O-poor electrical double layer and render a dendrite-free Zn2+-plating behavior. The formulated hybrid 2 m Zn(OTf)2 + 7 m DEC electrolyte endows the Zn electrode with an ability to achieve high cycling stability (over 3500 h at 5 mA cm-2 with 2.5 mA h cm-2) and supports the stable operation of Zn||V2O5·nH2O full battery. This efficient strategy with hydrophobic cosolvent suggests a promising direction for designing aqueous battery chemistries.

Aqueous Electrolytes with Hydrophobic Organic Cosolvents for Stabilizing Zinc Metal Anodes.

Metallic Zn is believed to be an ideal anode for aqueous batteries, but its reversibility is deteriorated by noncompact and dendritic Zn deposition along with interfacial parasitic reactions. Herein, it is reported that introducing cholinium (Ch+) cations into aqueous electrolytes enables a spatially compact, non‐dendritic, and corrosion‐free Zn electrode even at high areal capacity (5.0 and 10.0 mAh cm–2) using a pressure‐free electrolytic cell. This strategy is applicable to various Zn‐salt‐based aqueous electrolytes (e.g., 1 M ZnSO4, Zn(CH3COO)2, and ZnCl2). It is found that bulky Ch+ cations create a “leveling effect” to homogenize Zn deposition and render an H2O poor electrical double layer near Zn by favorably absorbing on the Zn surface. Moreover, Ch+ cations with –OH group disrupt the original H‐bonded network of water to reduce H2O‐induced side reactions and promote the Zn2+ de‐solvation by forming H‐bond with H2O. As a result, the Zn electrode in the optimized 1 M ZnSO4 with 4 M Ch+ electrolyte manifests remarkable electrochemical performances involving high Coulombic efficiency of 99.6% in Zn//Cu cell and prolonged cycling stability over 2000 h in Zn//Zn cell (1.0 mA cm–2, 1.0 mAh cm–2). This work provides a new strategy for the design of compact and dendrite‐free Zn battery chemistry.

Cholinium Cations Enable Highly Compact and Dendrite‐Free Zn Metal Anodes in Aqueous Electrolytes

Building an artificial interphase layer for tackling uncontrollable Zn dendrites and serious side reactions is a highly desirable strategy, but it is often hampered by the limited Zn2+ transport. Here, a stable fluorine‐doped amorphous carbon (CF) artificial layer is constructed on a Cu current collector (CF‐Cu) via facile carbonization treatment of a fluoropolymer coating to realize underlying Zn deposition. As evidenced experimentally and theoretically, this inorganic CF layer with ionic conductivity and electronic insulation successfully triggers dendrite‐free Zn deposition at the CF‐Cu interface with preferred Zn(002) crystal plane stacking parallel to the substrate surface, thus greatly promoting the inhibition of Zn‐dendrites and blocking of interfacial side reactions. The introduced fluorine atoms as abundant zincophilic sites play an important role in driving fast zinc‐ion transfer kinetics, which can partly convert into ZnF2 as an artificial solid Zn2+ conductor to further guide uniform Zn deposition. Consequently, the CF‐Cu electrode enables high reversibility with 99% coulombic efficiency and a long cycling stability of 1900 cycles at 2 mA cm–2. The integrated CF‐Cu@Zn anode achieves up to 2200 h cycles with a low voltage polarization. This study provides inspiration for the design of artificial interphase layers for stable nondendritic metal batteries.

A Multifunctional Artificial Interphase with Fluorine‐Doped Amorphous Carbon layer for Ultra‐Stable Zn Anode

Functional carbon materials for high-performance Zn metal anodes

Reshaping the electrolyte structure and interface chemistry for stable aqueous zinc batteries

Rechargeable Zn batteries hold great practicability for cost-effective sustainable energy storage but suffer from irreversibility of the Zn anode in aqueous electrolytes due to parasitic H2 evolution, corrosion, and dendrite growth. Herein, we report a non-flammable, dilute, and hydrous organic electrolyte by dissolving low-cost hydrated Zn(ClO4)2·6H2O in trimethyl phosphate (TMP), which homogenizes plating/stripping and enables in situ formation of a Zn3(PO4)2–ZnCl2-rich interphase to stabilize the Zn anode. A dilute 0.5 m Zn(ClO4)2·6H2O/TMP electrolyte featuring a H2O-poor Zn2+-solvation sheath and low water activity enables significantly enhanced Zn reversibility and a wider electrochemical window than the concentrated counterpart. In this formulated electrolyte, the Zn anode exhibits a high efficiency of 99.5% over 500 cycles, long-term cycling for 1200 h (5 mA h cm−2 at 5 mA cm−2) and stable operation at 50 °C. The results would guide the design of hydrous organic electrolytes for practical rechargeable batteries employing metallic electrode materials.

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Ning Zhang

Papers

Reshaping the electrolyte structure and interface chemistry for stable aqueous zinc batteries

Aqueous Electrolytes with Hydrophobic Organic Cosolvents for Stabilizing Zinc Metal Anodes.

Cholinium Cations Enable Highly Compact and Dendrite‐Free Zn Metal Anodes in Aqueous Electrolytes

Non-flammable, dilute, and hydrous organic electrolytes for reversible Zn batteries

Zn metal anodes stabilized by an intrinsically safe, dilute, and hydrous organic electrolyte