Cations-Intercalated Two-Dimensional Titanium Carbonitride (Ti₃CNT_x) MXene for High-Performance Supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-performance electrochemical energy storage devices (EESDs) require advanced electrode materials with high pseudocapacitance and cycle life.
• Two-dimensional (2D) titanium carbonitride (Ti3CNT x) MXene shows promise for EESDs due to its conductivity and surface chemistry.

Purpose of the Study:

• To develop a cost-effective method for improving Ti3CNT x MXene structure by reducing sheet restacking.
• To investigate the intercalation of various cations (Li+, Na+, Mg2+, K+) to enhance gravimetric capacitance.
• To explore K+-Ti3CNT x as a high-performance anode material for potassium-ion storage.

Main Methods:

• Investigated methods to reduce sheet restacking and improve the aggregated structure of Ti3CNT x MXenes.
• Utilized hydrophilic (Li+, Na+, Mg2+) and hydrophobic (K+) cation intercalation to enhance capacitance.
• Characterized the electrochemical performance of K+-Ti3CNT x as an anode material in potassium-ion storage devices.

Main Results:

• Engineered K+-Ti3CNT x demonstrated a high charge storage capacity of 1003 F g-1, nearly tripling that of delaminated Ti3CNT x (d-Ti3CNT x).
• The K+-Ti3CNT x anode exhibited improved environmental stability and superior electrochemical performance due to the pillaring effect of K+.
• An AC //K+-Ti3CNT x device achieved an energy density of 37 Wh kg-1 with 95% capacity retention over 10,000 cycles and >99% Coulombic efficiency.

Conclusions:

• Hydrophobic K+ intercalation in Ti3CNT x MXene significantly enhances redox-active sites and electrochemical performance.
• K+-Ti3CNT x is a promising anode material for advanced potassium-ion storage devices, outperforming conventional supercapacitors.
• The developed material offers excellent energy density and long-term cycling stability, crucial for practical EESDs.