posted on 2021-09-13, 11:34authored byShuhui Xia, Yuanyuan Zhang, Yun Zhao, Xiao Wang, Jianhua Yan
Porous carbon nanofibers (PCNFs)
have rich channels for transporting
ions, molecules, and nanoparticles, but the control over their porous
structures is a challenge. Here, we report a scalable electrospinning
technique by using poly(tetrafluoroethylene) as a pore template, boric
acid as a cross-linking agent, and polyvinyl alcohol and polyurethane
as dual carbon precursors to fabricate flexible PCNFs with tunable
geometries and macro/meso/microporous structures. In the water solvent,
the negatively charged template cross-links with the positively charged
carbon precursors to form a stable sol for electrospinning. By varying
the mass ratios of these precursors, the electrospun hybrid nanofibers
are directly transformed into B–F–N–O doped PCNFs
with tunable macro-, meso-, and micropores after carbonization. The
porosity of an individual PCNF is as high as ∼85%, and the
pore volume can be tuned from 0.23 to 0.58 cm3·g–1. When constructing high-sulfur-content (86 wt %)
electrodes with the freestanding PCNF films, the porous structures
with rich electroactive sites provide rapid pathways for poly-anions
and have strong chemisorption of poly-sulfides, leading to a great
electrochemical performance. The reported strategy offers a new perspective
for synthesizing hierarchical PCNFs with appealing applications.