Interface Engineering of MOF-Derived Co₃O₄@CNT and CoS₂@CNT Anodes with Long Cycle Life and High-Rate Properties in Lithium/Sodium-Ion Batteries

Metal-organic framework materials can be converted into carbon-based nanoporous materials by pyrolysis, which have a wide range of applications in energy storage. Here, we design special interface engineering to combine the carbon skeleton and nitrogen-doped carbon nanotubes (CNTs) with the transition metal compounds (TMCs) well, which mitigates the bulk effect of the TMCs and improves the conductivity of the electrodes. Zeolitic imidazolate framework-67 is used as a precursor to form a carbon skeleton and a large number of nitrogen-doped CNTs by pyrolysis followed by the in situ formation of Co3O4 and CoS2, and finally, Co3O4@CNTs and CoS2@CNTs are synthesized. The obtained anode electrodes exhibit a long cycle life and high-rate properties. In lithium-ion batteries (LIBs), Co3O4@CNTs have a high capacity of 581 mAh g(-1) at a high current of 5 A g(-1), and their reversible capacity is still 1037.6 mAh g(-1) after 200 cycles at 1 A g(-1). In sodium-ion batteries (SIBs), CoS2@CNTs have a capacity of 859.9 mAh g(-1) at 0.1 A g(-1) and can be retained at 801.2 mAh g(-1) after 50 cycles. The unique interface engineering and excellent electrochemical properties make them ideal anode materials for high-rate, long-life LIBs and SIBs.