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Simple synthesis of highly catalytic carbon-free MnCo2O4@Ni as an oxygen electrode for rechargeable Li-O2 batteries with long-term stability.

Kalubarme RS, Jadhav HS, Ngo DT, Park GE, Fisher JG, Choi YI, Ryu WH, Park CJ - Sci Rep (2015)

Bottom Line: The highly porous structure of the electrode allows the electrolyte and oxygen to diffuse effectively into the catalytically active sites and hence improve the cell performance.The Li-O2 cell has demonstrated a cyclability of 119 cycles while maintaining a moderate specific capacity of 1000 mAh g(-1).Furthermore, the synergistic effect of the fast kinetics of electron transport provided by the free-standing structure and the high electro-catalytic activity of the spinel oxide enables excellent performance of the oxygen electrode for Li-O2 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Material Science and Engineering, Chonnam National University, 77, Yongbongro, Bukgu, Gwangju 500-757, South Korea.

ABSTRACT
An effective integrated design with a free standing and carbon-free architecture of spinel MnCo2O4 oxide prepared using facile and cost effective hydrothermal method as the oxygen electrode for the Li-O2 battery, is introduced to avoid the parasitic reactions of carbon and binder with discharge products and reaction intermediates, respectively. The highly porous structure of the electrode allows the electrolyte and oxygen to diffuse effectively into the catalytically active sites and hence improve the cell performance. The amorphous Li2O2 will then precipitate and decompose on the surface of free-standing catalyst nanorods. Electrochemical examination demonstrates that the free-standing electrode without carbon support gives the highest specific capacity and the minimum capacity fading among the rechargeable Li-O2 batteries tested. The Li-O2 cell has demonstrated a cyclability of 119 cycles while maintaining a moderate specific capacity of 1000 mAh g(-1). Furthermore, the synergistic effect of the fast kinetics of electron transport provided by the free-standing structure and the high electro-catalytic activity of the spinel oxide enables excellent performance of the oxygen electrode for Li-O2 cells.

No MeSH data available.


Related in: MedlinePlus

FE-SEM images of the surface of the KB-MCO electrode.(a) after the 1st full discharge; and (b) charge, and the FSMCO electrode; (c) after the discharge; and (d) charge. Insets in (a,c) show corresponding TEM images.
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f5: FE-SEM images of the surface of the KB-MCO electrode.(a) after the 1st full discharge; and (b) charge, and the FSMCO electrode; (c) after the discharge; and (d) charge. Insets in (a,c) show corresponding TEM images.

Mentions: FE-SEM and TEM images were obtained to investigate the change in surface of the KB-MCO and FSMCO electrodes after the 1st full discharge and charge cycle. Figure 5 shows the FE-SEM and TEM images observed for the KB-MCO and FSMCO electrodes after full discharge and charge. On the whole, these two electrodes exhibited quite different morphologies. For the FSMCO electrode, the nanorods appear to be covered evenly with discharge products (Fig. 5c), whereas distinct toroid shaped discharge products were formed on the KB-MCO electrode. Specifically, the toroid shape was found to consist of nano-flakes. Toroid-like morphologies of Li2O2 have also been reported for the electrode containing KB as the carbon source3647. Further, the nature of the discharge products formed on the surface of the electrodes was analyzed using XRD. The crystalline character of the discharge product was confirmed for the KB-MCO electrode. The peaks obtained in the pattern corresponded to the (100) and (101) planes of crystalline Li2O2 as shown in Supplementary Fig. S9. However, for the FSMCO, no additional peak was observed in the XRD pattern (Supplementary Fig. S9), which indicates the low degree of crystallinity of the discharge product. Furthermore, the formation of Li2O2 was verified by Raman spectroscopy. The presence of a peak at 780 cm−1 in the Raman plot (Supplementary Fig. S10) and the absence of a peak after charging confirms the reversibility of the amorphous Li2O2 formation on the FSMCO surface. As confirmed in Fig. 5b,d, the Li2O2 disappeared when the cell was charged to 4.2 V and, in particular, the bare MnCo2O4 nanorods reappeared for FSMCO. After charging, the formed discharge product is oxidized and the surface becomes ready for the next ORR process. These results imply that the FS-MCO catalyst without carbon affects both the morphology and crystallinity of the discharge product of Li2O2 simultaneously, thus improving the reversibility in each cycle through increased contact area between Li2O2 and the catalyst.


Simple synthesis of highly catalytic carbon-free MnCo2O4@Ni as an oxygen electrode for rechargeable Li-O2 batteries with long-term stability.

Kalubarme RS, Jadhav HS, Ngo DT, Park GE, Fisher JG, Choi YI, Ryu WH, Park CJ - Sci Rep (2015)

FE-SEM images of the surface of the KB-MCO electrode.(a) after the 1st full discharge; and (b) charge, and the FSMCO electrode; (c) after the discharge; and (d) charge. Insets in (a,c) show corresponding TEM images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543937&req=5

f5: FE-SEM images of the surface of the KB-MCO electrode.(a) after the 1st full discharge; and (b) charge, and the FSMCO electrode; (c) after the discharge; and (d) charge. Insets in (a,c) show corresponding TEM images.
Mentions: FE-SEM and TEM images were obtained to investigate the change in surface of the KB-MCO and FSMCO electrodes after the 1st full discharge and charge cycle. Figure 5 shows the FE-SEM and TEM images observed for the KB-MCO and FSMCO electrodes after full discharge and charge. On the whole, these two electrodes exhibited quite different morphologies. For the FSMCO electrode, the nanorods appear to be covered evenly with discharge products (Fig. 5c), whereas distinct toroid shaped discharge products were formed on the KB-MCO electrode. Specifically, the toroid shape was found to consist of nano-flakes. Toroid-like morphologies of Li2O2 have also been reported for the electrode containing KB as the carbon source3647. Further, the nature of the discharge products formed on the surface of the electrodes was analyzed using XRD. The crystalline character of the discharge product was confirmed for the KB-MCO electrode. The peaks obtained in the pattern corresponded to the (100) and (101) planes of crystalline Li2O2 as shown in Supplementary Fig. S9. However, for the FSMCO, no additional peak was observed in the XRD pattern (Supplementary Fig. S9), which indicates the low degree of crystallinity of the discharge product. Furthermore, the formation of Li2O2 was verified by Raman spectroscopy. The presence of a peak at 780 cm−1 in the Raman plot (Supplementary Fig. S10) and the absence of a peak after charging confirms the reversibility of the amorphous Li2O2 formation on the FSMCO surface. As confirmed in Fig. 5b,d, the Li2O2 disappeared when the cell was charged to 4.2 V and, in particular, the bare MnCo2O4 nanorods reappeared for FSMCO. After charging, the formed discharge product is oxidized and the surface becomes ready for the next ORR process. These results imply that the FS-MCO catalyst without carbon affects both the morphology and crystallinity of the discharge product of Li2O2 simultaneously, thus improving the reversibility in each cycle through increased contact area between Li2O2 and the catalyst.

Bottom Line: The highly porous structure of the electrode allows the electrolyte and oxygen to diffuse effectively into the catalytically active sites and hence improve the cell performance.The Li-O2 cell has demonstrated a cyclability of 119 cycles while maintaining a moderate specific capacity of 1000 mAh g(-1).Furthermore, the synergistic effect of the fast kinetics of electron transport provided by the free-standing structure and the high electro-catalytic activity of the spinel oxide enables excellent performance of the oxygen electrode for Li-O2 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Material Science and Engineering, Chonnam National University, 77, Yongbongro, Bukgu, Gwangju 500-757, South Korea.

ABSTRACT
An effective integrated design with a free standing and carbon-free architecture of spinel MnCo2O4 oxide prepared using facile and cost effective hydrothermal method as the oxygen electrode for the Li-O2 battery, is introduced to avoid the parasitic reactions of carbon and binder with discharge products and reaction intermediates, respectively. The highly porous structure of the electrode allows the electrolyte and oxygen to diffuse effectively into the catalytically active sites and hence improve the cell performance. The amorphous Li2O2 will then precipitate and decompose on the surface of free-standing catalyst nanorods. Electrochemical examination demonstrates that the free-standing electrode without carbon support gives the highest specific capacity and the minimum capacity fading among the rechargeable Li-O2 batteries tested. The Li-O2 cell has demonstrated a cyclability of 119 cycles while maintaining a moderate specific capacity of 1000 mAh g(-1). Furthermore, the synergistic effect of the fast kinetics of electron transport provided by the free-standing structure and the high electro-catalytic activity of the spinel oxide enables excellent performance of the oxygen electrode for Li-O2 cells.

No MeSH data available.


Related in: MedlinePlus