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

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 H₂ SO₄ 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.