Multi‐Pleated Alkalized Ti3C2Tx MXene‐Based Sandwich‐Like Structure Composite Nanofibers for High‐Performance Sodium/Lithium Storage

Abstract The volume expansion of CoFe 2 O 4 anode poses a significant challenge in the commercial application of lithium/sodium‐ion batteries (LIBs/SIBs). However, metal–organic‐frameworks (MOF) offer superior construction of heterostructures with refined interfacial interactions and lower ion diffusion barriers in Li/Na storage. In this study, the CoFe 2 O 4 @carbon nanofibers derived from MOF are produced through electrospinning, in situ growth followed by calcination, which are then confined within an MXene‐confined MOF‐derived porous CoFe 2 O 4 @carbon composite architecture under alkali treatment. The CoFe 2 O 4 nanofibers anchor on the alkalized MXene that is decorated with the NaOH solution to form a multi‐pleated structure. The sandwich‐like structure of the composite effectively alleviates the volume expansion and shortens the Li/Na‐ion diffusion path, which displays high capacity and outstanding rate performance as anode materials for LIBs/SIBs. As a consequence, the obtained CoFe 2 O 4 @carbon@alkalized MXene composite anode shows satisfied rate performance at current density of 10 A g −1 for LIBs (318 mAh·g −1 ) and 5 A g −1 for SIBs (149 mAh g −1 ). The excellent cycling performance is further demonstrated at a high current density, where it maintains a discharge capacity of 807 mAh g −1 at 2 A g −1 after 400 cycles for LIBs and 130 mAh g −1 at 1 A g −1 even after 1000 cycles for SIBs.