“‐NH‐” Homologation Driven Self‐Exfoliated Bipolar Covalent Organic Nanosheet as Dual‐Ion Binding Anode for High‐Performance Aqueous Zinc‐Based Dual‐Ion Battery

Rechargeable aqueous zinc‐ion batteries (AZIBs) offer safe, low‐cost, and sustainable alternatives to lithium‐ion systems. However, dendritic Zn growth downgrades Coulombic efficiency and cycling stability, limiting their practical deployment. Replacing Zn‐metal anodes with reversible organic anodes capable of efficient Zn 2+ storage with average discharge voltage below 0.6 V (vs Zn/Zn 2+ ) is superior yet challenging. Herein, we report a self‐exfoliated bipolar few‐layer polyimide‐based covalent organic nanosheet ( tht ‐NDA‐PI‐CON ) as anode, synthesized via solvent‐free organic flux route using “‐NH‐” homologation strategy, which promotes self‐exfoliation by introducing structural flexibility while simultaneously generating electron‐rich sp 3 ‐NH centres, acting as electronic buffer in between carbonyl and triazine units constructing a bipolar framework, enabling low‐energy barrier dual‐ion binding kinetics. The porous nanosheet, enriched with redox centres delivers 185 mAh g −1 at 0.2 A g −1 (84.6% contributes from single discharge plateau), high‐rate capability (78.6% retention/5 A g −1 ), and 81% capacity retention over 5000 cycles. Ex situ analyses and first‐principles calculations reveal Zn 2+ coordination with carbonyl and triazine sites during discharge, while SO 4 2− is stabilized by homologated ‐NH‐ unit upon charging. When paired with MnO 2 , full cell delivers record energy density of 82.73 Wh kg −1 with 84.8% capacity retention over 3000 cycles, demonstrating its potential for next‐generation Zn‐based dual‐ion battery technologies.