Eutectic Electrolytes Chemistry for Rechargeable Zn Batteries

Abstract

Rechargeable zinc batteries (RZBs) have proved to be promising candidates as an alternative to lithium‐ion batteries due to their low cost, inherent safety, and environmentally benign features. While designing cost‐effective electrolyte systems with excellent compatibility with electrode materials, high energy/power density as well as long life‐span challenge their further application as grid‐scale energy storage devices. Eutectic electrolytes as a novel class of electrolytes have been extensively reported and explored taking advantage of their feasible preparation and high tunability. Recently, some perspectives have summarized the development and application of eutectic electrolytes in metal‐based batteries, but their infancy requires further attention and discussion. This review systematically presents the fundamentals and definitions of eutectic electrolytes. Besides, a specific classification of eutectic electrolytes and their recent progress and performance on RZB fields are introduced as well. Significantly, the impacts of various composing eutectic systems are disserted for critical RZB chemistries including attractive features at electrolyte/electrode interfaces and ions/charges transport kinetics. The remaining challenges and proposed perspectives are ultimately induced, which deliver opportunities and offer practical guidance for the novel design of advanced eutectic electrolytes for superior RZB scenarios.

Eutectic Electrolyte with Unique Solvation Structure for High‐Performance Zinc‐Ion Batteries

“…[15,16] Unlike conventional electrolytes with solvated cations and anions through simple dissolving, the eutectic electrolytes contain complex anions and cations, which are formed through the strong interactions between the components. [17][18][19] For example, 2.0 M ZnCl 2 aqueous electrolyte contains solvated Zn ] + cations. [20] Compared with the traditional electrolytes, the eutectic electrolytes possess many characteristics, such as structural flexibility, good thermal/chemical stability, low vapor pressure, and wide potential windows.…”

“…When DESs is applied as the electrolyte for batteries, it is usually called eutectic electrolyte [15, 16] . Unlike conventional electrolytes with solvated cations and anions through simple dissolving, the eutectic electrolytes contain complex anions and cations, which are formed through the strong interactions between the components [17–19] . For example, 2.0 M ZnCl 2 aqueous electrolyte contains solvated Zn 2+ cations and Cl − anions, while AlCl 3 /acetamide (AcA) eutectic electrolyte has AlCl 4 − and Al 2 Cl 7 − anions and [AlCl 2 (AcA) 2 ] + cations [20] .…”

Regulating zinc metal anodesvianovel electrolytes in rechargeable zinc-based batteries

“…[53][54][55][56] Though a few varieties of anodes exist in the form of galvanized and zinc-free anodes, the most widely used anode material is still pure zinc foil so far. [57][58][59] The reliability and reversibility of Zn akes are vital to achieve outstanding performance of ZMBs. [60][61][62][63][64][65][66] However, some issues and challenges including the dendrite growth and shape change, gassing, corrosion, and passivation caused by the harsh HER side reaction with aqueous electrolytes still remain, limiting their actual applications.…”

Protic ethers as highly efficient hydrogen-bond regulators for aqueous eutectic electrolytes

“…However, this eutectic electrolyte-designed approach still faces challenges associated with eutectic component selection and composition collocation. 12 Considering its infancy stage, eutectic-solvent systems require a pivotal study of novel "eutectic regime" dedicated to the molecular structure transition from ordinary "diluted solutions" to unique "solvent-ineutectic" domination. 13 To circumvent the challenges above, most recent studies have demonstrated "water-in-DES" (WiDES) 14 and hydrated eutectic electrolytes 15 through the precise regulation of H 2 O content to suppress water activity and facilitate ion transport.…”

“…However, this eutectic electrolyte-designed approach still faces challenges associated with eutectic component selection and composition collocation. 12 Considering its infancy stage, eutectic-solvent systems require a pivotal study of novel “eutectic regime” dedicated to the molecular structure transition from ordinary “diluted solutions” to unique “solvent-in-eutectic” domination. 13…”