Tuning MXene Pathways via Silver Nanoparticle Size Variations for Anode-Free Battery Applications.

MXenes, a class of two-dimensional titanium carbide materials, have emerged as promising materials for film-based applications due to their exceptional properties. However, their densely layered structures hinder ion diffusion, metal-ion mobility, and nanoscale particle transfer, limiting their potential in energy-related applications. Expanding and controlling interlayer spacing is essential for overcoming these limitations and optimizing MXene performance. In this study, silver nanoparticles (AgNPs) measuring 20 and 55 nm in size were incorporated into dense MXene structures to control and expand their pathways. X-ray diffraction confirmed the lamellar structure of pristine MXene, and detailed analyses using electron microscopy and small-angle neutron scattering demonstrated that the size and concentration of AgNPs directly influenced pathway expansion. The interlayer spacing increased significantly, with widths growing from 2.4 nm to ∼25 nm as the AgNP parameters varied. Electrochemical impedance spectroscopy results revealed that the densely packed structure of pristine MXene was unsuitable for use as an anode-current collector coating in batteries. In contrast, the MXene/AgNP composite demonstrated effective functionality due to the expanded pathways, which improved ion transfer and conductivity. These findings underscore the importance of pathway engineering and the use of additive insertion methods in advancing MXene-based materials for energy storage and other functional applications.