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Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance.

Yang Z, Lv J, Pang H, Yan W, Qian K, Guo T, Guo Z - Sci Rep (2015)

Bottom Line: Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment.The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside.The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode.

View Article: PubMed Central - PubMed

Affiliation: National &Local United Engineering Laboratory of Flat Panel Display Technology, Fuzhou University, Fuzhou 350002, P. R. China.

ABSTRACT
Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg(-1), a high reversible specific capacity of 560.5 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

No MeSH data available.


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FE-SEM images of as-prepared CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers:(a) acidized CNTs, (b) high magnification image of the acidized CNTs, (c) CNTs/MnOx, (d) CNTs/MnOx-Carbon hybrid nanofibers.
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f2: FE-SEM images of as-prepared CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers:(a) acidized CNTs, (b) high magnification image of the acidized CNTs, (c) CNTs/MnOx, (d) CNTs/MnOx-Carbon hybrid nanofibers.

Mentions: The morphologies of the as-prepared MnO2 powders, CNTs/MnOx, and CNTs/MnOx-Carbon hybrid nanofibers, as well as the acidized CNTs, have been respectively investigated by field-emission scanning electron microscopy (FE-SEM) (see Fig. 2 and Supporting Information Fig. S2). The pure MnO2 nanoparticles prepared by LCRR with diameters of only a few nanometers (see Fig. S2) are so small that only some aggregates consisting of many tiny MnO2 nanoparticles can be seen. As shown in Fig. 2, the acidized CNTs, the one-dimensional template precursors, with diameters of 15–20 nm and lengths extending to a few micrometers are randomly aligned. After the liquid chemical redox reaction (LCRR) and subsequent carbonization treatment in argon at 500 °C for 2 h, the one-dimensional morphology is maintained (see Fig. 2(c,d)), and the CNTs/MnOx-PVP hybrid nanofibers have finally been converted to fully carbonized CNTs/MnOx-Carbon hybrid nanofibers with diameters of 20–30 nm, which are slightly thicker than those of the acidized CNTs. Both the CNTs/MnOx hybrid nanofibers and the CNTs/MnOx-Carbon hybrid nanofibers are encapsulated by many MnOx nanocrystals than 5 nm in size, which are tightly aligned around the CNT core, and those MnOx nanoscale particles are too small to be discerned clearly from each other. Additionally, the template precursor, the acidized CNTs, the as-prepared CNTs/MnOx-Carbon hybrid nanofibers, and the CNTs/MnOx hybrid nanofibers all have become attached together to form many meso/micro holes/voids/pores (see Fig. 2(b–d)). These meso/micro holes/voids/pores that are formed in these hybrid nanofibers, as well as the high content of carbon matrix (see Supporting Information Fig. S3) with high conductivity, including both the CNT cores and the carbon matrix coated on the outside, would ensure a high electrode-electrolyte contact area, so that a large amount of lithium ions can be accommodated without any remarkable degradation of the structure during the charge/discharge cycling, which is favorable for both lithium ion storage and lithium ion diffusion.


Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance.

Yang Z, Lv J, Pang H, Yan W, Qian K, Guo T, Guo Z - Sci Rep (2015)

FE-SEM images of as-prepared CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers:(a) acidized CNTs, (b) high magnification image of the acidized CNTs, (c) CNTs/MnOx, (d) CNTs/MnOx-Carbon hybrid nanofibers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664925&req=5

f2: FE-SEM images of as-prepared CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers:(a) acidized CNTs, (b) high magnification image of the acidized CNTs, (c) CNTs/MnOx, (d) CNTs/MnOx-Carbon hybrid nanofibers.
Mentions: The morphologies of the as-prepared MnO2 powders, CNTs/MnOx, and CNTs/MnOx-Carbon hybrid nanofibers, as well as the acidized CNTs, have been respectively investigated by field-emission scanning electron microscopy (FE-SEM) (see Fig. 2 and Supporting Information Fig. S2). The pure MnO2 nanoparticles prepared by LCRR with diameters of only a few nanometers (see Fig. S2) are so small that only some aggregates consisting of many tiny MnO2 nanoparticles can be seen. As shown in Fig. 2, the acidized CNTs, the one-dimensional template precursors, with diameters of 15–20 nm and lengths extending to a few micrometers are randomly aligned. After the liquid chemical redox reaction (LCRR) and subsequent carbonization treatment in argon at 500 °C for 2 h, the one-dimensional morphology is maintained (see Fig. 2(c,d)), and the CNTs/MnOx-PVP hybrid nanofibers have finally been converted to fully carbonized CNTs/MnOx-Carbon hybrid nanofibers with diameters of 20–30 nm, which are slightly thicker than those of the acidized CNTs. Both the CNTs/MnOx hybrid nanofibers and the CNTs/MnOx-Carbon hybrid nanofibers are encapsulated by many MnOx nanocrystals than 5 nm in size, which are tightly aligned around the CNT core, and those MnOx nanoscale particles are too small to be discerned clearly from each other. Additionally, the template precursor, the acidized CNTs, the as-prepared CNTs/MnOx-Carbon hybrid nanofibers, and the CNTs/MnOx hybrid nanofibers all have become attached together to form many meso/micro holes/voids/pores (see Fig. 2(b–d)). These meso/micro holes/voids/pores that are formed in these hybrid nanofibers, as well as the high content of carbon matrix (see Supporting Information Fig. S3) with high conductivity, including both the CNT cores and the carbon matrix coated on the outside, would ensure a high electrode-electrolyte contact area, so that a large amount of lithium ions can be accommodated without any remarkable degradation of the structure during the charge/discharge cycling, which is favorable for both lithium ion storage and lithium ion diffusion.

Bottom Line: Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment.The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside.The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode.

View Article: PubMed Central - PubMed

Affiliation: National &Local United Engineering Laboratory of Flat Panel Display Technology, Fuzhou University, Fuzhou 350002, P. R. China.

ABSTRACT
Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg(-1), a high reversible specific capacity of 560.5 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

No MeSH data available.


Related in: MedlinePlus