Lean-water hydrogel electrolyte for zinc ion batteries

Abstract

Solid polymer electrolytes (SPEs) and hydrogel electrolytes were developed as electrolytes for zinc ion batteries (ZIBs). Hydrogels can retain water molecules and provide high ionic conductivities; however, they contain many free water molecules, inevitably causing side reactions on the zinc anode. SPEs can enhance the stability of anodes, but they typically possess low ionic conductivities and result in high impedance. Here, we develop a lean water hydrogel electrolyte, aiming to balance ion transfer, anode stability, electrochemical stability window and resistance. This hydrogel is equipped with a molecular lubrication mechanism to ensure fast ion transportation. Additionally, this design leads to a widened electrochemical stability window and highly reversible zinc plating/ stripping. The full cell shows excellent cycling stability and capacity retentions at high and low current rates, respectively. Moreover, superior adhesion ability can be achieved, meeting the needs of flexible devices.

Controlling Dendrite Growth with Xylan-Enhanced Hydroxyl-Rich Hydrogel Electrolyte for Efficient Zn-Ion Energy Storage

“…25,26 The adhesion strengths of PBXHE on different substrates are somewhat lower than those of PBHE (1.47, 2.07, and 3.43 kPa) (Figure S2), which stems from more interactions between hydroxyl groups (adhesion sites) and water molecules in the water-rich cross-linked PBXHE network. 27 Nevertheless, the adhesion capability of PBXHE is still satisfactory compared with that of some reported hydrogel electrolytes, which contributes to the stability of the electrolyte−electrode interface. 14,28 Superior electrochemical characteristics of hydrogel electrolytes play a pivotal role in zinc-based devices, ensuring fast transport kinetics, high resistance to dendrites and parasitic effects, and long life.…”

“…The quantitative adhesion strengths of PBXHE are determined to be 1.12, 1.49, and 1.88 kPa on copper sheet, zinc sheet, and carbon paper used as current collectors, respectively (Figure e). The bonding of PBXHE to metals involves possible electrostatic attraction and interaction with the metal (known as metal complexation), originating from boron ester bonds and hydroxyl groups in PBXHE (Figure f). , The adhesion strengths of PBXHE on different substrates are somewhat lower than those of PBHE (1.47, 2.07, and 3.43 kPa) (Figure S2), which stems from more interactions between hydroxyl groups (adhesion sites) and water molecules in the water-rich cross-linked PBXHE network . Nevertheless, the adhesion capability of PBXHE is still satisfactory compared with that of some reported hydrogel electrolytes, which contributes to the stability of the electrolyte–electrode interface. , Figure g presents photographs of PBXHE under stretching, twisting, and bending, indicating its potential in flexible devices.…”

Challenges, Strategies, and Perspectives of Anode Protection in Aqueous Zinc-Ion Batteries

“…e) A linear sweep voltammetry of ZIG (20, 40, 60 wt % water content), PAM, and PAA (conventional HPEs). Reprinted with permission from ref . Copyright 2023, Springer Nature Publishing.…”

Organohydrogel electrolytes with solvated structure regulation for highly reversible low-temperature zinc metal batteries

“…More crucially, the HER, corrosion, and dendrites occurring at the Zn anode cannot fundamentally be eliminated by HPEs. 33,34 Organohydrogels with organic co-solvent can coordinate with Zn 2+ and reduce water activity. Moreover, the low-temperature tolerance of RAZIBs can be enhanced simultaneously by the incorporation of organic solvents with fast ion transport at low temperatures.…”