A Mechanistic Study of MXene Current Collectors for Lithium-Metal-Based Batteries

Lithium metal is widely investigated as a high-energy-density anode replacement for graphite in lithium-ion batteries. It is important for next-generation lithium-metal-based battery technologies. However, lithium dendrites tend to grow during deposition and stripping, resulting in poor battery life or short circuits. Literature shows that using MXene instead of copper as the current collector can mitigate lithium dendrite growth. Two mainstream hypotheses for dendrite suppression include forming a hexagonal close-packed structured lithium layer and a homogeneous growth of solid-electrolyte interphase (SEI) on the surface of MXene. However, there is a lack of experimental evidence to support those hypotheses. Here we used a suite of characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), X-ray photoelectron spectroscopy (XPS), <i>in situ </i>Raman spectroscopy, scanning electron microscopy (SEM), and <i>operando</i> optical microscopy to investigate the crystal structure, SEI, and morphology of lithium nucleated on Ti₃C₂T<i>_x </i>MXene at different rates and capacity.