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

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 similar to 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.