Ion desolvation for boosting the charge storage performance in Ti₃C₂ MXene electrode

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Fast and efficient energy storage relies on understanding ion intercalation in host materials.
• Limited knowledge exists on ion desolvation and surface termination interactions impacting energy storage mechanisms.

Purpose of the Study:

• To investigate Li-ion intercalation in Ti3C2 MXenes with varying surface chemistries (HF- and MS-MXenes).
• To visualize ion desolvation and solvent-ion co-intercalation at the atomic scale.
• To elucidate the role of surface terminations and ion desolvation in charge storage capacity.

Main Methods:

• Atomic-scale visualization of ion desolvation and co-intercalation.
• Utilizing multiple characterization techniques to analyze MXene surface interactions.
• Comparing Li-ion intercalation in HF-Ti3C2 (F-, OH-, O-terminated) and MS-Ti3C2 (O-, Cl-terminated) MXenes.

Main Results:

• Direct visualization of complete ion desolvation in MS-MXenes and solvent-ion co-intercalation in HF-MXenes.
• Complete ion desolvation in Cl- and O-terminated MS-MXenes correlates with a dense solid electrolyte interface layer.
• O-rich surface terminations on MS-MXenes are identified as crucial for efficient Li-ion storage.

Conclusions:

• Non-electrostatic ion-electrode interactions and ion desolvation significantly influence energy storage performance.
• Surface chemistry of MXenes plays a critical role in dictating ion intercalation and charge storage.
• Findings provide insights for designing advanced energy storage devices with enhanced capacity.