Fundamentals and perspectives in developing zinc-ion battery electrolytes: a comprehensive review

Zhang, Tengsheng; Tang, Yan; Guo, Shan; Cao, Xinxin; Pan, Anqiang; Fang, Guozhao

doi:10.1039/d0ee02620d

Cited by 585 publications

(433 citation statements)

References 198 publications

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“…Zinc (Zn) metal anode is promising for aqueous batteries with both intrinsic safety and low‐cost metrics. [ 1–6 ] However, metallic Zn is thermodynamically unstable in aqueous environments, [ 7–12 ] where Zn deposition even during shelf time is continuously interfered by competitive hydrogen evolution through H 2 O decomposition (Zn + 2H 2 O → Zn(OH) 2 + H 2 ) and by consuming both the electrolyte and active Zn metal. This long‐neglected problem will remarkably affect calendar life of batteries, which is equivalently important with the intensively studied cycling life of batteries.…”

Section: Figurementioning

confidence: 99%

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

et al. 2021

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environments, [7-12] where Zn deposition even during shelf time is continuously interfered by competitive hydrogen evolution through H 2 O decomposition (Zn + 2H 2 O → Zn(OH) 2 + H 2) and by consuming both the electrolyte and active Zn metal. This long-neglected problem will remarkably affect calendar life of batteries, which is equivalently important with the intensively studied cycling life of batteries. As revealed in our preliminary quantitative study shown in Figure 1a, immersing Zn in 2 m ZnSO 4 electrolyte will induce an ≈0.25 mmol h-1 cm-2 hydrogen flux. The continuous hydrogen evolution will cause local pH changes, which further induce the formation of loose and brittle Zn 4 SO 4 (OH) 6 •xH 2 O (3Zn(OH) 2 + ZnSO 4 •xH 2 O → Zn 4 SO 4 (OH) 6 •xH 2 O), as revealed in Figure 1b. [13-18] It is generally assumed that these by-products augment the tortuosity and irregularity at the electrode/electrolyte interface with physical contact surface being increased (Figure 1c-h), which will further accelerate hydrogen evolution reaction. The above issues necessitate an effective method to detect hydrogen evolution. Nevertheless, for a Zn-based battery, these assumption and hypotheses are only based on oversimplified observations of battery swelling, gas bubbles, or conducting polarization curve in the absence of Zn 2+ condition, not reflecting physical truth of battery. [19-21] Hydrogen production during electrochemical procedure and even shelf time has not been precisely quantified. Consequently, efforts to make Zn metal a valid anode material may be misdirected. Quantifying the hydrogen production on the electrode during Zn deposition is key to understanding the mechanisms leading to capacity loss and battery failure. On the other hand, these Zn protrusions caused by hydrogen evolution reaction will attract more Zn 2+ flux ("tip" effect) [22] under concentrated electric field during electrochemical cycling, thus accelerating the vertical growth of Zn dendrites instead of planar growth and hydrogen production further flourish (Figure 1g). Up to now, various strategies have been evolved to prohibit the Zn dendrite growth, such as electrolyte optimization, [8,23-25] Zn surface coating, [9,21,26-29] and alloying. [30] To some extent, these strategies stabilize Zn metal, but they do The hydrogen evolution in Zn metal battery is accurately quantified by in situ battery-gas chromatography-mass analysis. The hydrogen fluxes reach 3.76 mmol h −1 cm −2 in a Zn//Zn symmetric cell in each segment, and 7.70 mmol h −1 cm −2 in a Zn//MnO 2 full cell. Then, a highly electronically insulating (0.11 mS cm −1) but highly Zn 2+ ion conductive (80.2 mS cm −1) ZnF 2 solid ion conductor with high Zn 2+ transfer number (0.65) is constructed to isolate Zn metal from liquid electrolyte, which not only prohibits over 99.2% parasitic hydrogen evolution but also guides uniform Zn electrodeposition. Precisely quantitated, the Zn@ZnF 2 //Zn@ZnF 2 cell only produces 0.02 mmol h −1 cm −2 of hydrogen (0.53% of the Zn//Zn cell). Encouragingly, a hig...

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Section: Figurementioning

confidence: 99%

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

et al. 2021

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“…The electronically insulating property of the hopeite SEI layer is significant for forming the necessary potential gradient across the SEI to drive Zn 2+ transfer through the layer. [ 40,41 ]…”

Section: Figurementioning

confidence: 99%

Electrolyte Design for In Situ Construction of Highly Zn²⁺‐Conductive Solid Electrolyte Interphase to Enable High‐Performance Aqueous Zn‐Ion Batteries under Practical Conditions

et al. 2021

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Rechargeable aqueous Zn‐ion batteries promise high capacity, low cost, high safety, and sustainability for large‐scale energy storage. The Zn metal anode, however, suffers from the dendrite growth and side reactions that are mainly due to the absence of an appropriate solid electrolyte interphase (SEI) layer. Herein, the in situ formation of a dense, stable, and highly Zn2+‐conductive SEI layer (hopeite) in aqueous Zn chemistry is demonstrated, by introducing Zn(H2PO4)2 salt into the electrolyte. The hopeite SEI (≈140 nm thickness) enables uniform and rapid Zn‐ion transport kinetics for dendrite‐free Zn deposition, and restrains the side reactions via isolating active Zn from the bulk electrolyte. Under practical testing conditions with an ultrathin Zn anode (10 µm), a low negative/positive capacity ratio (≈2.3), and a lean electrolyte (9 µL mAh−1), the Zn/V2O5 full cell retains 94.4% of its original capacity after 500 cycles. This work provides a simple yet practical solution to high‐performance aqueous battery technology via building in situ SEI layers.

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“…Current research on rechargeable Zn batteries (RZBs) focuses mainly on continuous cycling with Zn foil as the anode and low‐mass‐loading cathode and having a high negative/positive (NP) ratio. [ 1,2 ] However, using Zn as both the active substance and current collector will give rise to many issues, [ 3,4 ] when the battery is scaled up, calendar life is considered, and/or a low NP ratio is adopted. As a result, Zn powder (Zn‐P) is a popular choice in real industrial applications and can be adapted for commercialization with a tunable surface area to accommodate existing manufacturing technologies and ensure low cost.…”

Section: Introductionmentioning

confidence: 99%

Calendar Life of Zn Batteries Based on Zn Anode with Zn Powder/Current Collector Structure

et al. 2021

Advanced Energy Materials

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Zn foil is widely used for studying the stability and dendrite formation behavior of Zn anodes. The reported long cycling life of rechargeable Zn batteries (RZBs) is obtained by testing a battery immediately after its fabrication neglecting the aging effects. The cycling performance demonstrated cannot, however, have practical applications. Using Zn foil as both the working electrode and current collector will cause many problems when the battery is scaled up. A Zn powder (Zn‐P)/current collector configuration is more practical. In this work, the corrosion of the Zn‐P@Cu anode‐induced cell swelling is first quantitatively studied. During the aging process of the Zn‐P@Cu electrode, hydrogen forms on the surface of Cu and the Zn‐P dissolves resulting in morphological changes. These phenomena can be attributed to galvanic corrosion between Cu and Zn. To address this issue, tin with a higher overpotential for hydrogen generation is plated on Cu surface. The results indicate that hydrogen evolution is ameliorated. With a low NP ratio (mass) of 10:7, considerably better storage and cycling performance are achieved for Zn‐P@Cu//MnO2. These results highlight the need to focus on the calendar life of RZBs and corrosion of the Zn anode.

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Fundamentals and perspectives in developing zinc-ion battery electrolytes: a comprehensive review

Abstract: The development of low-cost and high-safety zinc-ion batteries (ZIBs) has been extensively discussed and reviewed in recent years, but the work on comprehensive discussion and perspective in developing zinc-ion electrolytes...

Cited by 585 publications

References 198 publications

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

Electrolyte Design for In Situ Construction of Highly Zn²⁺‐Conductive Solid Electrolyte Interphase to Enable High‐Performance Aqueous Zn‐Ion Batteries under Practical Conditions

Calendar Life of Zn Batteries Based on Zn Anode with Zn Powder/Current Collector Structure

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Fundamentals and perspectives in developing zinc-ion battery electrolytes: a comprehensive review

Abstract: The development of low-cost and high-safety zinc-ion batteries (ZIBs) has been extensively discussed and reviewed in recent years, but the work on comprehensive discussion and perspective in developing zinc-ion electrolytes...

Cited by 585 publications

References 198 publications

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

Toward Practical High‐Areal‐Capacity Aqueous Zinc‐Metal Batteries: Quantifying Hydrogen Evolution and a Solid‐Ion Conductor for Stable Zinc Anodes

Electrolyte Design for In Situ Construction of Highly Zn2+‐Conductive Solid Electrolyte Interphase to Enable High‐Performance Aqueous Zn‐Ion Batteries under Practical Conditions

Calendar Life of Zn Batteries Based on Zn Anode with Zn Powder/Current Collector Structure

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Electrolyte Design for In Situ Construction of Highly Zn²⁺‐Conductive Solid Electrolyte Interphase to Enable High‐Performance Aqueous Zn‐Ion Batteries under Practical Conditions