Stabilizing Zinc Anode Reactions by Polyethylene Oxide Polymer in Mild Aqueous Electrolytes

Abstract

Zn dendrites growth and poor cycling stability are significant challenges for rechargeable aqueous Zn batteries. Zn metal deposition-dissolution in aqueous electrolytes is typically determined by Zn anode-electrolyte interfaces. In this work, the role of a long-chain polyethylene oxide (PEO) polymer as a multifunctional electrolyte additive in stabilizing Zn metal anodes is reported. PEO molecules suppress Zn 2+ ion transfer kinetics and regulate Zn 2+ ion concentration in the vicinity of Zn anodes through interactions between ether groups of PEO and Zn 2+ ions. The suppressed Zn 2+ ion transfer kinetics and homogeneous Zn 2+ ion distribution at the interface promotes dendrite-free homogeneous Zn deposition. In addition, electrochemically inert PEO molecules adsorbed onto Zn anodes can protect the anode surfaces from H 2 generation and, thereby, enhance their electrochemical stability. Stable cycling over 3000 h and high reversibility (Coulombic efficiency > 99.5%) of Zn anodes is demonstrated in 1 m ZnSO 4 electrolyte with 0.5 wt% PEO. This finding provides helpful insights into the mechanism of Zn metal anodes stabilization by low-cost multifunctional polymer electrolyte additives that stabilize interfacial reactions.

Heterometallic Seed‐Mediated Zinc Deposition on Inkjet Printed Silver Nanoparticles Toward Foldable and Heat‐Resistant Zinc Batteries

“…The initial nucleation stage is an important step in determining the zinc plating quality. [ 32 ] To estimate the zincophilic degree of the AgNPs@CC, nucleation overpotential of Zn on different electrode surfaces were investigated at a low current density of 0.2 mA cm −2 . The Zn nucleation overpotential is the voltage difference between tip potential and the flat part of the voltage plateau.…”

“…Accordingly, several strategies have been devoted to suppressing dendrite growth and minimizing side reactions, including optimizing electrolyte composition, [ 12–24 ] adopting gel or solid electrolyte, [ 25–27 ] and coating multifunctional protective layers. [ 28–33 ] Metallic Zn anode is a hostless electrode that is dynamically deposited and stripped at the Zn‐electrolyte interfaces, eventually undergoing huge volume variation during repeated Zn deposition‐dissolution processes. [ 34 ] Compared with common planar configuration, constructing 3D conductive skeletons with large free space is a feasible approach to accommodate metallic Zn, which can reduce the local current density and minimize the volume variation of Zn deposits.…”

Issues and rational design of aqueous electrolyte for Zn‐ion batteries

“…In the mild aqueous electrolyte, Zn 2+ with fast reaction kinetics on the Zn anode surface may facilitate the inhomogeneous Zn deposition. A long‐chain polyethylene oxide polymer (PEO) additive in ZnSO 4 electrolyte can effectively slow down Zn 2+ transfer to regulate concentration distribution and electrolyte flux through interactions between Zn 2+ and ether group in PEO, which ensures homogeneous Zn 2+ distribution on the interface between Zn anode and electrolyte to achieve a uniform deposition/dissolution process 79 . Some organics additives introduced in the aqueous electrolyte remain in the anode surface and participate in the interfacial reactions, which may complicate the continuous Zn plating/stripping processes.…”

A Patternable and In Situ Formed Polymeric Zinc Blanket for a Reversible Zinc Anode in a Skin‐Mountable Microbattery

“…To improve the stability of Zn anodes, a general strategy is to coat a protective polymer layer onto the Zn anode, which prohibits the contact of Zn with reactive water molecules and corrosive ions in electrolytes. [16][17][18][19] Despite high efficiency in corrosion inhibition, the polymeric coating, to some extent, impedes the access of cations to the Zn anode, resulting in the large overpotential of the plating/stripping process and the limitation of the reaction kinetics. [15,18] Towards a highperformance Zn anode, it is of great importance to develop a polymeric protection layer that resolves corrosion-induced problems and allows for fast kinetics, including low overpotential of plating/stripping and a fast charge/discharge ability.…”