Zinc ion interactions in a two-dimensional covalent organic framework based aqueous zinc ion battery

The two-dimensional structural features of covalent organic frameworks (COFs) can promote the electrochemical storage of cations like H⁺, Li⁺, and Na⁺ through both faradaic and non-faradaic processes. However, the electrochemical storage of cations like Zn²⁺ ion is still unexplored although it bears a promising divalent charge. Herein, for the first time, we have utilized hydroquinone linked β-ketoenamine COF acting as a Zn²⁺ anchor in an aqueous rechargeable zinc ion battery. The charge-storage mechanism comprises of an efficient reversible interlayer interaction of Zn²⁺ ions with the functional moieties in the adjacent layers of COF (−182.0 kcal mol⁻¹). Notably, due to the well-defined nanopores and structural organization, a constructed full cell, displays a discharge capacity as high as 276 mA h g⁻¹ at a current rate of 125 mA g⁻¹.