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Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries.

Nam SH, Kim YS, Shim HS, Kim JG, Bae Kim W - Nanoscale Res Lett (2011)

Bottom Line: We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx).The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide.Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Chemdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea. wbkim@gist.ac.kr.

ABSTRACT
We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx). The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoOxthin-film (CoOxTF) electrodes, the CuNFs@CoOxelectrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoOxcomposite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.

No MeSH data available.


Related in: MedlinePlus

AC impedance spectra for both samples. The experimental results are presented as Nyquist plots by applying a sine wave with amplitude of 5 mV over the frequency range 100 kHz to 10 mHz, which were measured at E = 1.6 V (vs. Li+/Li) after the cycles.
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Figure 5: AC impedance spectra for both samples. The experimental results are presented as Nyquist plots by applying a sine wave with amplitude of 5 mV over the frequency range 100 kHz to 10 mHz, which were measured at E = 1.6 V (vs. Li+/Li) after the cycles.

Mentions: In Figure 5, AC impedance measurements were performed to probe the kinetic factors contributing to the capacity and rate performance. The equivalent circuit analysis is based on a Randles equivalent circuit for an electrochemical system, in which Rb is the bulk resistance, corresponding to the resistance value at the high-frequency intercept of the semicircle with the real axis [9,25]. Rct and Cct are the resistance of the charge-transfer and double-layer capacitance, respectively. The Rb value of the CuNFs@CoOxwas similar to that of the bare CoOxTF electrodes, whereas the Rct and Cct values for the CuNFs@CoOxwere much smaller than those for CoOxTF. A considerable change in the sum of RSEI and Rct from 344 Ω was observed for CoOxTF to 96 Ω for CuNFs@CoOx, indicating an enhanced electrical conductivity arising from the composite, which implies that the charge transfer was significantly improved by the embedded CuNF network structure within the CoOxTF. This result confirmed that the embedded CuNF network could not only contribute to the high conductivity of the overall electrode, but also largely improve the electrochemical properties of CoOxduring the cyclings.


Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries.

Nam SH, Kim YS, Shim HS, Kim JG, Bae Kim W - Nanoscale Res Lett (2011)

AC impedance spectra for both samples. The experimental results are presented as Nyquist plots by applying a sine wave with amplitude of 5 mV over the frequency range 100 kHz to 10 mHz, which were measured at E = 1.6 V (vs. Li+/Li) after the cycles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211358&req=5

Figure 5: AC impedance spectra for both samples. The experimental results are presented as Nyquist plots by applying a sine wave with amplitude of 5 mV over the frequency range 100 kHz to 10 mHz, which were measured at E = 1.6 V (vs. Li+/Li) after the cycles.
Mentions: In Figure 5, AC impedance measurements were performed to probe the kinetic factors contributing to the capacity and rate performance. The equivalent circuit analysis is based on a Randles equivalent circuit for an electrochemical system, in which Rb is the bulk resistance, corresponding to the resistance value at the high-frequency intercept of the semicircle with the real axis [9,25]. Rct and Cct are the resistance of the charge-transfer and double-layer capacitance, respectively. The Rb value of the CuNFs@CoOxwas similar to that of the bare CoOxTF electrodes, whereas the Rct and Cct values for the CuNFs@CoOxwere much smaller than those for CoOxTF. A considerable change in the sum of RSEI and Rct from 344 Ω was observed for CoOxTF to 96 Ω for CuNFs@CoOx, indicating an enhanced electrical conductivity arising from the composite, which implies that the charge transfer was significantly improved by the embedded CuNF network structure within the CoOxTF. This result confirmed that the embedded CuNF network could not only contribute to the high conductivity of the overall electrode, but also largely improve the electrochemical properties of CoOxduring the cyclings.

Bottom Line: We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx).The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide.Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Chemdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea. wbkim@gist.ac.kr.

ABSTRACT
We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx). The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoOxthin-film (CoOxTF) electrodes, the CuNFs@CoOxelectrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoOxcomposite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.

No MeSH data available.


Related in: MedlinePlus