Tuning planar and selective Zn evolution promoted by densely grown covalent organic framework towards high performance zinc batteries

Abstract

Zn dendrites generation and excess electrolyte consumption prevent the practical application of aqueous Zn batteries (AZBs). Herein, zincophilic separators (glass fibers@ covalent organic framework, GF@COF) are synthesized via a facile one-step solvothermal method based on Schiff base reaction. Specifically, the separator surface is densely decorated by in situ grown covalent organic framework (COF). Zincophilic N and O containing groups in COF exhibit excellent binding capability with Zn ions, driving homogenous Zn distribution and boosting Zn-ion flux. COF can promote shielding of (100) and (101) plane of Zn metal and directional exposure of (002) plane, steering selective and planar Zn deposition along (002) plane. The mechanism of achieving non-dendrite growth and reduced electrolyte loss has been confirmed by in situ XRD, in situ FT-IR and theoretical calculation. Electrochemical performances of ultrastable rate capability of 4500 h at ambient condition and high reversible capacity of 78.6 mAh g⁻¹ (capacity retention of 94 %) even after 2000 cycles at a large current of 5 A g⁻¹ for MnO₂ based full cell are observed, which are substantially superior than previous literature.