Pillar-Structured Ti₃C₂T_x MXene with Engineered Interlayer Spacing for High-Performance Magnesium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Two-dimensional (2D) Ti3C2Tx MXene is promising for non-lithium-ion batteries due to its conductivity and capacity.
• Rechargeable magnesium batteries offer high energy density and safety but face challenges with sluggish Mg2+ ion kinetics in MXene.
• The large polarity of Mg2+ ions hinders their insertion into MXene layers, limiting battery performance.

Purpose of the Study:

• To enhance the magnesium ion storage capability of Ti3C2Tx MXene.
• To overcome the sluggish kinetics of Mg2+ ion insertion into MXene layers.
• To improve the electrochemical performance of MXene as a cathode material for magnesium batteries.

Main Methods:

• A self-assembly strategy was employed to intercalate a hyperbranched polyethylene ionomer containing quaternary ammonium ions into Ti3C2Tx MXene.
• The interlayer spacing of MXene was expanded, and its affinity to THF-based electrolytes was improved.
• Electrochemical performance was evaluated for magnesium batteries using the modified MXene as a cathode material.

Main Results:

• The ionomer-modified delaminated MXene exhibited significantly improved electrochemical performance.
• Promising cycling stability was achieved, with 86% capacity retention after 400 cycles at 200 mA g-1.
• Outstanding high-rate performance was demonstrated, retaining 110 mAh g-1 at 1,000 mA g-1 compared to 213 mAh g-1 at 20 mA g-1.

Conclusions:

• The intercalation of hyperbranched polyethylene ionomer effectively enhances the magnesium ion storage capability of Ti3C2Tx MXene.
• The modified MXene demonstrates superior cycling stability and high-rate performance, making it a viable cathode material for magnesium batteries.
• This approach offers a promising pathway for developing high-performance magnesium-ion battery technologies.