Polymer Coating with Balanced Coordination Strength and Ion Conductivity for Dendrite‐Free Zinc Anode

• Published in: Advanced materials (Weinheim) 2024-01, Vol.36 (3), p.e2307727-n/a
• Main Authors: Cai, Xiaomin, Tian, Wenzhi, Zhang, Zekai, Sun, Yan, Yang, Lei, Mu, Hongchun, Lian, Cheng, Qiu, Huibin
• Format: Article
• Language: English
• Subjects: Anodes; aqueous zinc ion battery; Coating; Coordination; Decay rate; Electrolysis; Glass fibers; Ion migration; Low level; Nucleation; poly(2‐vinylpyridine); polymer coating; Polymer coatings; Reaction kinetics; Synergistic effect; Wettability; zinc dendrite
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202307727

Decorating Zn anodes with functionalized polymers is considered as an effective strategy to inhibit dendrite growth. However, this normally brings extra interfacial resistance rendering slow reaction kinetics of Zn2+. Herein, a poly(2‐vinylpyridine) (P2VP) coating with modulated coordination strength and ion conductivity for dendrite‐free Zn anode is reported. The P2VP coating favors a high electrolyte wettability and rapid Zn2+ migration speed (Zn2+ transfer number, tZn2+ = 0.58). Electrostatic potential calculation shows that P2VP mildly coordinates with Zn2+ (adsorption energy = −0.94 eV), which promotes a preferential deposition of Zn along the (002) crystal plane. Notably, the use of partially (26%) quaternized P2VP (q‐P2VP) further reduces the interfacial resistance to 126 Ω, leading to a high ion migration speed (tZn2+ = 0.78) and a considerably low nucleation overpotential (18 mV). As a result of the synergistic effect of mild coordination and partial electrolysis, the overpotential of the q‐P2VP‐decorated Zn anode retains at a considerably low level (≈46 mV) over 1000 h at a high current density of 10 mA cm−2. The assembled (NH4)2V6O16·1.5H2O || glass fiber || q‐P2VP‐Zn full cell reveals a lower average capacity decay rate of only 0.018% per cycle within 500 cycles at 1 A g−1. Poly(2‐vinylpyridine) (P2VP) limits the unrestricted 2D diffusion of zinc ions through soft coordination and the partially quaternized derivative (q‐P2VP) further enables a balance between coordination trapping and ion transporting, leading to a rapid ion migration speed and a lower capacity decay.