Fullerene Intercalation of MXene Toward Super‐Long‐Cycle Sodium Ion Storage

Abstract2D layered MXene‐based materials are applied as cation‐intercalation electrode materials for sodium‐ion batteries (SIBs) due to their layered structures but suffer from spontaneous restacking during Na+ insertion and deintercalation processes, resulting in sluggish reaction kinetics and poor cycling stability. Herein, fullerene C60 is intercalated covalently into the interlayer of Ti3C2Tx MXene nanosheets by using a low‐temperature hydrothermal reaction between a water‐soluble C60 derivative and hydrophilic MXene nanosheets, resulting in enlarged interlayer spacing of MXene nanosheets from 12.8 to 14.1 Å and consequently retarded self‐restacking. Moreover, the strong electron extraction ability of C60 facilitates electron transfer from MXene to C60, enabling faster charge transport during Na+ transportation. The as‐prepared C60@MXene hybrid is applied as a novel anode of SIBs, exhibiting outstanding electrochemical performance and super‐long cycling stability. C60@MXene‐based SIB delivers a specific capacity of 226.8 mAh g−1 at 0.1 A g−1 after 300 cycles, which surpasses that obtained from the pristine MXene anode, and retains 94.5% capacity at 1 A g−1 after 10 000 cycles. DFT simulations confirm that C60‐induced enlarged interlayer spacing benefits Na+ migrations, which is responsible for improved electrochemical performance and cycling stability.