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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

Schematic illustration of the growth mechanism for the free standing spinel MnCo2O4 nanorod arrays on Ni foam substrate as a carbon-free oxygen electrode for Li-O2 batteries.
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f1: Schematic illustration of the growth mechanism for the free standing spinel MnCo2O4 nanorod arrays on Ni foam substrate as a carbon-free oxygen electrode for Li-O2 batteries.

Mentions: Figure 1 schematically illustrates the strategy for the direct growth of ternary spinel MnCo2O4 nanorod arrays on metallic Ni foam substrates. In this process, the fresh Ni foam was slightly etched in an ultrasonic bath containing a mixture of HCl and HNO3 to remove the surface oxide layers and form fresh surface for the growth of spinel oxide. The etched Ni substrate was then immersed in the reaction solution containing Mn and Co precursors. During the hydrothermal process, at the initial temperature, the hydrolysis–precipitation process was initiated with the help of the reaction between urea and the metal ions leading to the formation of a thin seed layer of Mn, Co–hydroxide on the Ni substrate as shown in Supplementary Fig. S1. A very thin layer was observed on the nickel foam compared with the pristine Ni surface when removed from the solution after reaction for 1 h. The formed layer can act as the nucleation center for the growth of nanorod arrays. In the further hydrothermal process, the newly formed nuclei grew perpendicularly on the seed layer. As a result, large-scale, self-aligned Mn, Co–hydroxide nanorod arrays were formed on the conductive Ni foam. Some chestnut bur-like structures that might have grown from the pre-existing nanorod arrays were also formed, as confirmed in Fig. 2. The reactions for the formation of spinel MnCo2O4 are as follows.


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)

Schematic illustration of the growth mechanism for the free standing spinel MnCo2O4 nanorod arrays on Ni foam substrate as a carbon-free oxygen electrode for Li-O2 batteries.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Schematic illustration of the growth mechanism for the free standing spinel MnCo2O4 nanorod arrays on Ni foam substrate as a carbon-free oxygen electrode for Li-O2 batteries.
Mentions: Figure 1 schematically illustrates the strategy for the direct growth of ternary spinel MnCo2O4 nanorod arrays on metallic Ni foam substrates. In this process, the fresh Ni foam was slightly etched in an ultrasonic bath containing a mixture of HCl and HNO3 to remove the surface oxide layers and form fresh surface for the growth of spinel oxide. The etched Ni substrate was then immersed in the reaction solution containing Mn and Co precursors. During the hydrothermal process, at the initial temperature, the hydrolysis–precipitation process was initiated with the help of the reaction between urea and the metal ions leading to the formation of a thin seed layer of Mn, Co–hydroxide on the Ni substrate as shown in Supplementary Fig. S1. A very thin layer was observed on the nickel foam compared with the pristine Ni surface when removed from the solution after reaction for 1 h. The formed layer can act as the nucleation center for the growth of nanorod arrays. In the further hydrothermal process, the newly formed nuclei grew perpendicularly on the seed layer. As a result, large-scale, self-aligned Mn, Co–hydroxide nanorod arrays were formed on the conductive Ni foam. Some chestnut bur-like structures that might have grown from the pre-existing nanorod arrays were also formed, as confirmed in Fig. 2. The reactions for the formation of spinel MnCo2O4 are as follows.

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