Facile Fabrication of Ultrathin Bimetal‐Organic Nanosheets as High‐Performance Anode of Lithium‐Ion Batteries

Abstract Two‐dimensional metal‐organic frameworks (2D MOFs) with more exposed active sites and stable structures are auspicious electrode materials for high‐performance lithium‐ion batteries (LIBs). In the current work, ultrasonic treatment was used to prepare two‐dimensional CoNi‐BDC ultrathin nanosheets (N‐CoNi‐BDC) by coordinating Ni2+, Co2+, and benzenedicarboxylic acid (BDC). The N‐CoNi‐BDC was used as the anode of LIBs, demonstrating an exceptional reversible storage capacity of 1358 mAh g−1 after 200 cycles at 0.1 A g−1. In addition, a charging capacity of 757 mAh g−1 was observed at a high current density of 1 A g−1 without observable capacity degradation up to 300 cycles. The superior behavior of N‐CoNi‐BDC was attributed to its distinct morphology of ultrathin nanosheets with more exposed active sites and stable structures. Ex‐situ FTIR and XPS results revealed that the benzene ring, carboxylate, and Ni2+ in N‐CoNi‐BDC were the active parts of lithium‐ion storage.