Highly aligned Ti₃C₂T_x MXene films with high anisotropic thermal conductivity

High-density integration in modern electronic components induces severe heat accumulation, compromising operational stability and device longevity. Traditional metallic thermal conductors are heavily restricted by their substantial mass density and poor mechanical processability in lightweight electronics, demanding anisotropic materials that can provide robust thermal insulation across the out-of-plane direction while facilitating rapid heat dissipation along the in-plane direction. Here, we fabricate scalable and highly aligned Ti₃C₂T_x MXene films using the minimally intensive layer delamination method followed by vacuum-assisted filtration. Employing frequency-domain thermoreflectance, we achieve a precise characterization of directional heat transport on identical samples, revealing an exceptional thermal anisotropy ratio of 85. The fabricated films exhibit a significantly suppressed room-temperature out-of-plane thermal conductivity of 0.54 ± 0.09 W m^-1 K^-1 and an in-plane thermal conductivity of 46 ± 6 W m^-1 K^-1. Temperature-dependent characterization shows that out-of-plane thermal conductivity exhibits a positive temperature coefficient up to 353 K before stabilizing into a saturation plateau near 373 K, confirming that cross-plane heat transport is fundamentally regulated by the dense interlayer physical boundaries. At the microscopic interface, surface hydroxyl groups and interfacial hydrogen-bonding networks may modify local inter-flake phonon transport channels. The in-plane thermal conductivity decreases overall with increasing temperature, reducing the anisotropy while preserving substantial directional contrast. This work provides a versatile and high-performance platform for implementing structurally oriented MXene assemblies in advanced directional thermal management.