Mapping the Design of Electrolyte Materials for Electrically Rechargeable Zinc–Air Batteries

Abstract

Electrically rechargeable zinc–air batteries (ERZABs) have attracted substantial research interest as one of the best candidate power sources for electric vehicles, grid‐scale energy storage, and portable electronics owing to their high theoretical capacity, low cost, and environmental benignity. However, the realization of ERZABs with long cycle life and high energy and power densities is still a considerable challenge. The electrolyte, which serves as the ionic conductor, is one of the core components of ERZABs, as it plays a significant role during the discharge–charge process and greatly influences the rechargeability, operating voltage, lifespan, power density, and safety of ERZABs. Herein, the fundamental electrochemistry of electrolyte materials for ERZABs and the associated challenges are presented. Furthermore, recent advances in electrolyte materials for ERZABs, including alkaline aqueous electrolytes, nonalkaline electrolytes, ionic liquids, and semisolid‐state electrolytes are discussed. This work aims to provide insights into the future exploration of high‐performance electrolytes and thus promote the development of ERZABs.

A MOF‐Derivative Decorated Hierarchical Porous Host Enabling Ultrahigh Rates and Superior Long‐Term Cycling of Dendrite‐Free Zn Metal Anodes

“…In order to address the issues mentioned above, several strategies have been proposed to regulate the Zn plating/stripping behaviors for stable Zn metal batteries, including surface modification, [ 12–14 ] electrolyte optimization, [ 15–17 ] and electrode structural design. [ 18–20 ] For instance, an ultrathin MXene layer and glucose have been used as an artificial layer and a multifunctional electrolyte additive to stabilize Zn metal anodes, respectively.…”

“…[6][7][8] Unfortunately, the uncontrolled formation of dendrites, undesired side reactions (e.g., corrosion, hydrogen evolution, and by-product formation), and huge volume variation during repeated Zn deposition-dissolution processes of the host-less metallic Zn anode not only limit the efficiency of plating and stripping, but also result in a remarkably short lifespan, or even internal short-circuiting. [9][10][11] In order to address the issues mentioned above, several strategies have been proposed to regulate the Zn plating/stripping behaviors for stable Zn metal batteries, including surface modification, [12][13][14] electrolyte optimization, [15][16][17] and electrode structural design. [18][19][20] For instance, an ultrathin MXene layer and glucose have been used as an artificial layer and a multifunctional electrolyte additive to stabilize Zn metal anodes, Aqueous Zn metal batteries have attracted much attention due to their high intrinsic capacity, high safety, and low cost.…”

“Water‐in‐Salt” Nonalkaline Gel Polymer Electrolytes Enable Flexible Zinc‐Air Batteries with Ultra‐Long Operating Time

“…Hydroxide ions (OH − ) exhibits high mobility in water-based liquid or semi-solid electrolytes, which is considered to be due to their unique "Grotthuss" mechanism. [6] The OH − migration is formed by specific fluctuations in the local hydrogen bonds network. Second, gel polymer electrolytes based on KOH and Zn(OTF) 2 have different charge and discharge mechanisms.…”

“…[4,5] Solid-state ZABs assembled with gel polymer electrolyte commonly have good capability to withstand mechanical deformation with slight sacrifice of the electrochemical performance, which demonstrates a great potential in the real scenarios of wearable electronic devices. [6][7][8] At present, primary ZABs have been commercialized, and known as power sources methods have slowed down the rate of water evaporation in gel polymer electrolytes to different extents. Unfortunately, they could not completely and thoroughly solve the issue.…”

In Situ Integrating Highly Ionic Conductive LDH‐Array@PVA Gel Electrolyte and MXene/Zn Anode for Dendrite‐Free High‐Performance Flexible Zn–Air Batteries

“…In the ZABs with alkaline aqueous electrolytes, inhomogeneous Zn dissolution occurs during discharge and the produced zincate ions are highly soluble, which leads to the nonuniform re-deposition of metallic Zn on the electrode surface during next charge process, finally resulting in harmful Zn dendrites (Figure S20, Supporting Information). [56] Herein, to investigate the influence of electrode-electrolyte interfacial structure on the Zn deposition state for ZABs with GPEs, we evaluate the surface microstructure evolution of the long-time cycled Zn-based anode and the electrode-electrolyte interfacial compatibility for the ZABs with pure PVA, Mix-PVA@LDH, and MXene/Zn-LDH-array@PVA. As shown in Figure 6a and Figure S21a in the Supporting Information, needle-like dendrites are observed on the surface of cycled Zn anode for the ZAB with pure PVA GPE, and there exists a distinct void gap at the interface between Zn anode and water-loss PVA electrolyte, indicating the poor interfacial contact.…”