Design of L‐asparaginasespacer Molecules Intercalated 2D Ti₂C with Increased Interlayer Spacing towards High‐performance Sodium‐ions Storage

Abstract MXenes are promising insertion‐type two‐dimensional (2D) anode materials for rechargeable sodium‐ions batteries owing to unique layered structure, tunable interlayer spacing, and abundant surface functional groups. However, MXenes suffer from inevitably self‐stacking and narrow interlayer spacing, leading to the limited utilization of layered structure and sluggish ions diffusion kinetics. Herein, the (L‐asparaginase) LAG molecules as intercalation spacers were intercalated into the interlayer of Ti₂C by hydrogen‐bond interaction and electrostatic interaction to prepare the intercalated Ti₂C by LAG molecules (named as LAG‐Ti₂C). The LAG‐Ti₂C not only avoids self‐stacking and broadens interlayer spacing to maximumly utilize the layered structure, but also buffers the volume expansion via the pillar effect of intercalated LAG molecules. Such LAG‐Ti₂C could remarkably enhance the cycling stability and rate capability of Na⁺ ions storage. A decent specific capacity of 113.5 mAh g⁻¹ and high capacity retention of ~98.7 % at 0.1 A g⁻¹ after 1000 cycles can be presented. In addition, the LAG‐Ti₂C//AC sodium‐ions capacitor (SIC) delivers a high energy density of 27.56 Wh kg⁻¹ at power density of 3937.1 W kg⁻¹. The work promotes the further development of layered MXenes and optimizes electrochemical performance of sodium‐ions storage via the strategy of intercalating spacers.