A Covalent Organic Framework as a Long‐life and High‐Rate Anode Suitable for Both Aqueous Acidic and Alkaline Batteries

We prepared a covalent organic framework containing pyrazine (C=N) and phenylimino (−NH−) groups (HPP-COF) as an anode. The robust covalent linkage and the hydrogen bond network between −NH− and H₂O collectively improve the acid-alkaline co-tolerance and promote the rapid conduction of H⁺/OH⁻ by the Grotthuss mechanism. Thus the HPP-COF exhibits superior cycle stability and rate performance in both acidic and alkaline electrolytes.

Abstract

Aqueous rechargeable batteries are prospective candidates for large-scale grid energy storage. However, traditional anode materials applied lack acid-alkali co-tolerance. Herein, we report a covalent organic framework containing pyrazine (C=N) and phenylimino (−NH−) groups (HPP-COF) as a long-cycle and high-rate anode for both acidic and alkaline batteries. The HPP-COF′s robust covalent linkage and the hydrogen bond network between −NH− and water molecules collectively improve the acid-alkaline co-tolerance. More importantly, the hydrogen bond network promotes the rapid transport of H⁺/OH⁻ by the Grotthuss mechanism. As a result, the HPP-COF delivers a superior capacity and cycle stability (66.6 mAh g⁻¹@ 30 A g⁻¹, over 40000 cycles in 1 M H₂SO₄ electrolyte; 91.7 mAh g⁻¹@ 100 A g⁻¹, over 30000 cycles @ 30 A g⁻¹ in 1 M NaOH electrolyte). The work opens a new direction for the structural design and application of COF materials in acidic and alkaline batteries.

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