Thermally Conductive Ti3C2Tx Fibers with Superior Electrical Conductivity

Abstract

High-performance Ti₃C₂T_x fibers have garnered significant potential for smart fibers enabled fabrics. Nonetheless, a major challenge hindering their widespread use is the lack of strong interlayer interactions between Ti₃C₂T_x nanosheets within fibers, which restricts their properties. Herein, a versatile strategy is proposed to construct wet-spun Ti₃C₂T_x fibers, in which trace amounts of borate form strong interlayer crosslinking between Ti₃C₂T_x nanosheets to significantly enhance interactions as supported by density functional theory calculations, thereby reducing interlayer spacing, diminishing microscopic voids and promoting orientation of the nanosheets. The resultant Ti₃C₂T_x fibers exhibit exceptional electrical conductivity of 7781 S cm^-1 and mechanical properties, including tensile strength of 188.72 MPa and Young's modulus of 52.42 GPa. Notably, employing equilibrium molecular dynamics simulations, finite element analysis, and cross-wire geometry method, it is revealed that such crosslinking also effectively lowers interfacial thermal resistance and ultimately elevates thermal conductivity of Ti₃C₂T_x fibers to 13 W m^-1 K^-1, marking the first systematic study on thermal conductivity of Ti₃C₂T_x fibers. The simple and efficient interlayer crosslinking enhancement strategy not only enables the construction of thermal conductivity Ti₃C₂T_x fibers with high electrical conductivity for smart textiles, but also offers a scalable approach for assembling other nanomaterials into multifunctional fibers.

Keywords: Density functional theory simulation; Equilibrium molecular dynamics simulation; High electrical conductivity; Interlayer crosslinking; Thermally conductive Ti3C2Tx fibers.

Fig. 1

Preparation and characterization of Ti₃C₂T_x nanosheets and dispersion. a Schematic for fabrication of Ti₃C₂T_x. b SEM image of Ti₃AlC₂. c SEM, d AFM, e TEM, f HR-TEM and its FFT diffraction pattern (the inset), and g SAED images of Ti₃C₂T_x. POM images of Ti₃C₂T_x dispersion at concentrations of h 5 mg mL⁻¹, i 15 mg mL⁻¹, and j 25 mg mL⁻¹

Fig. 2

Fabrication, morphology, and chemical characterization of Ti₃C₂T_x fibers. a Schematic for fabricating Ti₃C₂T_x fibers. Photographs of Ti₃C₂T_x fibers b wound on the bobbin and c-d woven. SEM images of Ti₃C₂T_x fibers: e overall, f cross section, and g side-section views. h XPS full spectra, and XPS narrow spectra of i Ti 2p and j O 1s of Ti₃C₂T_x powder and Ti₃C₂T_x fiber

Fig. 3

Structural characterization, mechanical, and electrical properties of Ti₃C₂T_x fibers. a DFT calculations of borate ester bond between adjacent Ti₃C₂T_x nanosheets. b XRD patterns, c WAXS and SAXS (inset) patterns graphs, d plots of azimuthal angle according to the WAXS patterns, e density and porosity, f tensile strength and Young’s modulus, and g electrical conductivity of Ti₃C₂T_x fibers with different Na₂B₄O₇ contents. h Comparisons of electrical conductivity versus tensile strength of Ti₃C₂T_x fibers prepared with 0.75 wt% Na₂B₄O₇ against reported Ti₃C₂T_x-based fibers and Ti₃C₂T_x fibers

Fig. 4

ITR between Ti₃C₂T_x nanosheets and thermal conductivity of Ti₃C₂T_x fibers. a Schematic illustration of EMD simulation of borate ester covalently bonded Ti₃C₂T_x nanosheets. b ITR between borate ester covalently bonded Ti₃C₂T_x nanosheets with different Na₂B₄O₇ contents obtained by EMD simulation. c Extremely fine grid divisions corresponding to the finite element analysis models of Ti₃C₂T_x fibers with different Na₂B₄O₇ contents. d Temperature distribution of Ti₃C₂T_x fibers with different Na₂B₄O₇ contents under the same heating temperature and time simulated by finite element analysis. e λ of Ti₃C₂T_x fibers with different Na₂B₄O₇ contents. f Star-plot of the d-spacing, orientation order, density, ITR, and λ of Ti₃C₂T_x fibers with different Na₂B₄O₇ contents

Fig. 5

Joule heating performance of Ti₃C₂T_x fibers. a Temperature–time curves of single Ti₃C₂T_x fibers with different Na₂B₄O₇ contents when applied DC voltage of 7 V. b Temperature–time curves of single Ti₃C₂T_x fibers with 0.75 wt% Na₂B₄O₇ when applied DC voltage of 1 ~ 9 V. c Temperature–time curves and infrared thermal images of single Ti₃C₂T_x fibers at bending angles of 0° ~ 180°. d Infrared thermal images of Ti₃C₂T_x fibers with different letter shapes. e Temperature performance retention of Ti₃C₂T_x fibers after 5000 bending cycles