β‐Ketoenamine‐Linked Benzobisthiazole‐Based COF Nanocomposite Anode for High‐Performance Sodium‐Ion Battery

Sodium‐ion batteries (SIBs) have gained attention as a viable alternative to lithium‐ion batteries (LIBs), owing to their comparable ion storage mechanisms, lower cost, and high natural abundance of sodium. Nonetheless, the unfavorable interaction between Na + ions and graphite anodes relative to Li + ions presents a key obstacle in advancing SIB technology. To address this challenge and develop more efficient electrode materials, a redox‐active covalent organic framework (COF) based on β ‐ketoenamine‐linked benzobisthiazole is designed and grown in situ on multi‐walled carbon nanotubes (CNTs) via a polycondensation method. The incorporation of CNTs improves the electrical conductivity of the COF composite through π–π interactions. The high density of carbonyl and thiazole units within the framework enhances sodium‐ion storage, delivering a high specific capacity of 567 ± 12 mAh g −1 at 20 mA g −1 and maintaining excellent rate performance, with capacities reaching 150 mAh g −1 at 2 A g −1 . Furthermore, the COF composite exhibits high cyclic stability, retaining ≈77% of its initial capacity after 3000 charge‐discharge cycles. Electrochemical and spectroscopic analyses reveal that a combination of adsorption and insertion processes governs the sodium‐ion storage mechanism in the COF nanocomposite.