Interlayer engineering of Ti₃C₂T_x MXenes towards high capacitance supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Electrochemical pseudocapacitors utilize intercalation, electrosorption, and redox reactions for energy storage.
• MXenes exhibit high theoretical capacitances, making them promising for supercapacitor electrodes.
• Current MXene applications are limited by the inability to reach theoretical capacitance limits.

Purpose of the Study:

• To develop a rational design concept for MXene electrode materials to achieve theoretical capacitance limits.
• To enhance ion diffusion and charge transfer kinetics in MXene-based supercapacitors.
• To improve the overall performance of MXene materials for large-scale energy storage applications.

Main Methods:

• Interlayer engineering of Ti3C2Tx MXene via annealing under an ammonia atmosphere.
• Simultaneous optimization of interlayer spacing for ion diffusion and incorporation of heteroatoms for redox activity.
• Characterization of electrochemical performance, including capacitance, rate capability, and cyclability.

Main Results:

• Engineered MXene exhibits broadened and uniform interlayer spacing, facilitating fast ion diffusion.
• Incorporated heteroatoms act as redox-active sites, enhancing charge transfer.
• The modified MXene demonstrates significantly improved capacitance, rate performance, and cyclability compared to unmodified materials.
• Achieved performance surpasses that of other pseudocapacitive electrode materials.

Conclusions:

• Interlayer engineering is a viable strategy to unlock the theoretical capacitance of MXenes.
• The developed approach provides a pathway to high-performance supercapacitors for grid-scale applications.
• The engineered Ti3C2Tx MXene represents a significant advancement in pseudocapacitive electrode materials.