A Highly Reversible Zinc Anode for Rechargeable Aqueous Batteries

Abstract

Zinc metal holds a great potential as an anode material for next-generation aqueous batteries due to its suitable redox potential, high specific capacity, and low cost. However, the uncontrollable dendrite growth and detrimental side reactions with electrolytes hinder the practical application of this type of electrodes. To tackle the issues, an ultrathin (∼1 μm) sulfonated poly­(ether ether ketone) (SPEEK) solid–electrolyte interphase (SEI) is constructed onto the Zn anode surface by a facile spin-coating method. We demonstrate that the polymeric SEI simultaneously blocks the water molecules and anions, uniformizes the ion flux, and facilitates the desolvation process of Zn2+ ions, thus effectively suppressing the side reactions and Zn dendrite formation. As a result, the newly developed Zn@SPEEK anode enables a symmetric cell to stably operate over 1000 cycles at 5 mA cm–2 without degradation. Moreover, with the Zn anode paired with a MnO2 cathode, the full cell exhibits an improved Coulombic efficiency (over 99% at 0.1 A g–1), a superior rate capability (127 mA h g–1 at 2 A g–1), and excellent cycling stability (capacity retention of 70% over 1000 cycles at 1 A g–1). This work provides a facile yet effective strategy to address the critical challenges in Zn anodes, paving the way for the development of high-performance rechargeable aqueous batteries.

Stable Zinc Anodes Enabled by a Zincophilic Polyanionic Hydrogel Layer

“…In the meantime, negatively charged –SO 3 − groups can repel the SO 4 2− ions and retard the transport of water molecules. [ 31 ] This is regarded beneficial to achieving fast diffusion of Zn ions and uniform nucleation (Figure 1d). As shown in Figure 1f, the hydrogel layer on Zn plate is smooth and uniform without obvious cracks or wrinkles.…”

“…Hydrogels have been widely reported as a compatible electrolyte for flexible zinc-based batteries. [29][30][31][32][33] The H 2 O-saturated…”

“…Hydrogels have been widely reported as a compatible electrolyte for flexible zinc‐based batteries. [ 29–33 ] The H 2 O‐saturated framework and the good polymeric crosslinking degree provides sufficient 3D transport channels for Zn 2+ and presents efficient elasticity to accommodate dendrites protrusion. [ 34 ] In addition, tailorable properties (e.g., self‐healing, ionic conductivity, anti‐freezing ability, and mechanical strength) can be realized in hydrogels via additives modification and monomers combination.…”

“…The adsorption peaks locate around 1020 and 1200 cm −1 can be assigned to the stretching vibrations of OSO and SO bonds, respectively. [31,38] In the XPS spectrum of S 2p, the existence of -SO 3 − in indicated by the peak around 168 eV (Figure S3c, Supporting Information), and the peak at 399.6 eV in N 1s spectrum represents the NH on PAAm chains (Figure S3d, Supporting Information). [39] Hence, the results of FTIR and XPS indicate that -SO 3 − can be successfully induced by AMPS, which is one of key components toward its multiple functions.…”

Highly Reversible Zinc Anode Enabled by a Cation-Exchange Coating with Zn-Ion Selective Channels

“…Designing artificial solid-electrolyte interphase (SEI) films on a Zn anode shows great potential to address the aforementioned issues. − Polymers with good flexibility, high ionic conductivity, and superior processability are regarded as an ideal substance for the generation of artificial SEI films. − However, most of polymer-based artificial SEI films exhibit high polarization and inferior selective access of Zn 2+ ions. Cui et al .…”