A Rhombic 2D Conjugated Metal–Organic Framework as Cathode for High‐Performance Sodium‐Ion Battery

Abstract Two‐dimensional conjugated metal–organic frameworks (2D c ‐MOFs) have garnered significant attention as promising electroactive materials for energy storage. However, their further applications have been hindered by low capacity, limited cycling life, and underutilization of the active sites. Herein, we introduce Cu‐TBA (TBA = octahydroxyl tetrabenzoanthracene) with large conjugation units (narrow energy gap) and a unique rhombus topology as the cathode material for sodium‐ion batteries (SIBs). Notably, Cu‐TBA with a rhombus topology exhibits a high specific surface area (613 m 2 g −1 ) and metallic band structure. Additionally, Cu‐TBA outperforms its hexagonal counterpart, Cu‐HHTP (HHTP = 2,3,6,7,10,11‐hexahydroxyphenanthrene), demonstrating superior reversible capacity (153.6 mAh g −1 at 50 mA g −1 ) and outstanding cyclability with minimal capacity decay even after 3,000 cycles at 1 A g −1 . This work elucidates a new strategy to enhance the electrochemical performance of 2D c ‐MOFs cathode materials by narrowing the energy gap of organic linkers, effectively expanding the utilization of 2D c ‐MOFs for SIBs. This article is protected by copyright. All rights reserved