Ultrafine Sb nanoparticles in situ confined in covalent organic frameworks for high-performance sodium-ion battery anodes

Organic-inorganic hybrid materials hold great promise in commercial energy storage and conversion. This work aims to develop an advanced hybrid material of ultrafine antimony (Sb) nanoparticles uniformly anchored in the pores of COFs (Sb@NGA-CMP) through a facile in situ synthetic strategy. Sb³⁺ is introduced as an essential catalyst for COF formation and is subsequently fixed in the channels of the COFs by reduction. Such a well-designed architecture affords intimate electron interaction between the Sb nanoparticles and π-conjugated microporous polymers (CMPs) through the nitrogen groups, which greatly accelerates charge transfer along the COF skeleton. Meanwhile, the stable nanostructure of the ultrafine Sb encapsulated in the COFs effectively alleviates the high Sb volume expansion upon long cycling performance. This uniquely designed anode exhibits a high rate performance of 223 mA h g⁻¹ at 5 A g⁻¹ and an excellent sodium storage performance of 344 mA h g⁻¹ after 5000 long cycles at 1 A g⁻¹. Our work provides a promising and facile strategy to construct hybrid organic-inorganic materials for high-performance energy storage applications.