Facile Construction of Flexible Pitch@PAN Heterojunction Nanofibers with Excellent Conductivity Performance Based on Spontaneous Phase Separation Spinning Technology

Heterojunction nanofibers have attracted scholars' attention due to their structural and performance advantages. Their unique structure allows for a clear interface between two or even multiphase components of the material, fully leveraging the coupling and synergistic effects of the multicomponents and multilevel. We report a spontaneous phase separation spinning technology under ambient conditions suitable for the mixture of pitch and polyacrylonitrile (PAN), which achieves one-step facile preparation of pitch@PAN coaxial heterojunction nanofibers. This spinning method overcomes the problem of shape difficulty, easy melting, and merging of asphalt precursors during the preoxidation stage. Additionally, it can prepare conductive functional heterojunction nanofibers under environmental conditions without a coagulation bath. In the coaxial heterojunction fibers, the pitch phase is arranged on the outer surface of the heterojunction nanofiber to serve as a fast electronic transmission channel and enhance its conductivity, while the PAN phase acts as a mechanical skeleton structure inside. Based on the skin effect, the conductivity of heterojunction fibers is achieved at 238 Sm(-1), which significantly increases by 3-5 times. Meanwhile, its double-layer capacitance characteristic remains stable at different current densities, with a specific capacity of 173.61 Fg(-1) at 0.5 Ag(-1). This innovative method provides an efficient solution for the construction of heterojunction nanofibers, opening up new avenues for the multifunctional integrated flexible conductive fiber materials.