Variation in the interface strength of silicon with surface engineered Ti₃C₂ MXenes.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Advanced battery technologies necessitate robust electrode materials combining high-performance active materials like silicon (Si) with 2D materials such as MXenes.
• The interface between Si and MXenes is critical for achieving prolonged cycle stability and enhanced electrochemical performance in batteries.

Purpose of the Study:

• To investigate the interface strength variations between amorphous silicon and Ti3C2Tx MXenes.
• To determine how MXene surface functional groups (Tx) influence interface properties using first-principles calculations.

Main Methods:

• Utilized first-principles calculations based on Density Functional Theory (DFT).
• Simulated interfaces between amorphous Si and three Ti3C2 MXene substrates with varying surface functional groups (-OH, mixed -OH/-O, -F).

Main Results:

• The interface between amorphous Si and fully hydroxylated Ti3C2 (Ti3C2Tx with -OH groups) exhibited the highest interface strength (0.6 J m-2).
• Interface strength decreased with an increasing proportion of surface -O and -F groups on the Ti3C2 substrate.
• Analyzed electron redistribution and charge separation to elucidate the physicochemical factors governing interface strength.

Conclusions:

• Surface functionalization of MXenes significantly impacts their interface strength with silicon.
• Targeted surface engineering of MXenes, particularly promoting hydroxylation, can optimize electrode performance for advanced battery applications.
• Understanding these interfacial phenomena is key to developing next-generation battery electrodes.