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Graphene wrapped ordered LiNi0.5Mn1.5O4 nanorods as promising cathode material for lithium-ion batteries.

Tang X, Jan SS, Qian Y, Xia H, Ni J, Savilov SV, Aldoshin SM - Sci Rep (2015)

Bottom Line: The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100-200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite.Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability.As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g(-1) at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China [2] Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China.

ABSTRACT
LiNi0.5Mn1.5O4 nanorods wrapped with graphene nanosheets have been prepared and investigated as high energy and high power cathode material for lithium-ion batteries. The structural characterization by X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy indicates the LiNi0.5Mn1.5O4 nanorods prepared from β-MnO2 nanowires have ordered spinel structure with P4332 space group. The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100-200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite. Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability. As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g(-1) at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode. The outstanding performance of the LiNi0.5Mn1.5O4-graphene composite makes it promising as cathode material for developing high energy and high power lithium-ion batteries.

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Typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode.
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f7: Typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode.

Mentions: To evaluate the electrochemical properties of the LiNi0.5Mn1.5O4-graphene composite, half cells were assembled using lithium foil as both counter and reference electrodes. Fig. 7 compares the typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode between 3.5 and 5 V (vs. Li/Li+) at a scan rate of 0.05 mV s−1. For both electrodes, a pair of strong redox peaks at about 4.7 V (vs. Li/Li+) can be clearly observed, which can be attributed to the Ni2+/Ni4+ redox reactions827. The 4 V redox peaks, corresponding to the Mn3+/Mn4+ redox couple, are almost negligible in the CV curves for the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode, indicating their nearly perfect stoichiometry. By contrast, apart from the obvious 4 V (vs. Li/Li+) redox peaks, the disordered LiNi0.5Mn1.5O4 will show clear two pairs of redox peaks at about 4.7 V (vs. Li/Li+) in CV28. Previous studies indicate that the redox peak splitting at about 4.7 V (vs. Li/Li+) for the high voltage LixNi0.5Mn1.5O4 (0 < x < 1) is probably due to two separate redox couples of Ni2+/Ni3+ and Ni3+/Ni4+ and/or Li/vacancy ordering at x = 0.529. However, such peak splitting is not obvious for the ordered spinel as only one pair of redox peaks are observed in the typical CV curve. As discussed in our previous work on disordered LiNi0.5Mn1.5O4-δ thin films30, the ordering arrangement of Ni and Mn in the ordered spinel is probably not commensurate with the preferred Li/vacancy ordering at x = 0.5 so that the Ni/Mn ordering suppresses Li/vacancy ordering and redox peak splitting at about 4.7 V (vs. Li/Li+). In comparison with the bare LiNi0.5Mn1.5O4 nanorod electrode, the LiNi0.5Mn1.5O4-graphene composite electrode shows much smaller peak separation between the cationic peak and anodic peak in the CV curve, indicating the electrode polarization can be greatly reduced by incorporating the graphene nanosheets into LiNi0.5Mn1.5O4 nanorods.


Graphene wrapped ordered LiNi0.5Mn1.5O4 nanorods as promising cathode material for lithium-ion batteries.

Tang X, Jan SS, Qian Y, Xia H, Ni J, Savilov SV, Aldoshin SM - Sci Rep (2015)

Typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493710&req=5

f7: Typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode.
Mentions: To evaluate the electrochemical properties of the LiNi0.5Mn1.5O4-graphene composite, half cells were assembled using lithium foil as both counter and reference electrodes. Fig. 7 compares the typical CV curves of the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode between 3.5 and 5 V (vs. Li/Li+) at a scan rate of 0.05 mV s−1. For both electrodes, a pair of strong redox peaks at about 4.7 V (vs. Li/Li+) can be clearly observed, which can be attributed to the Ni2+/Ni4+ redox reactions827. The 4 V redox peaks, corresponding to the Mn3+/Mn4+ redox couple, are almost negligible in the CV curves for the bare LiNi0.5Mn1.5O4 nanorod electrode and the LiNi0.5Mn1.5O4-graphene composite electrode, indicating their nearly perfect stoichiometry. By contrast, apart from the obvious 4 V (vs. Li/Li+) redox peaks, the disordered LiNi0.5Mn1.5O4 will show clear two pairs of redox peaks at about 4.7 V (vs. Li/Li+) in CV28. Previous studies indicate that the redox peak splitting at about 4.7 V (vs. Li/Li+) for the high voltage LixNi0.5Mn1.5O4 (0 < x < 1) is probably due to two separate redox couples of Ni2+/Ni3+ and Ni3+/Ni4+ and/or Li/vacancy ordering at x = 0.529. However, such peak splitting is not obvious for the ordered spinel as only one pair of redox peaks are observed in the typical CV curve. As discussed in our previous work on disordered LiNi0.5Mn1.5O4-δ thin films30, the ordering arrangement of Ni and Mn in the ordered spinel is probably not commensurate with the preferred Li/vacancy ordering at x = 0.5 so that the Ni/Mn ordering suppresses Li/vacancy ordering and redox peak splitting at about 4.7 V (vs. Li/Li+). In comparison with the bare LiNi0.5Mn1.5O4 nanorod electrode, the LiNi0.5Mn1.5O4-graphene composite electrode shows much smaller peak separation between the cationic peak and anodic peak in the CV curve, indicating the electrode polarization can be greatly reduced by incorporating the graphene nanosheets into LiNi0.5Mn1.5O4 nanorods.

Bottom Line: The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100-200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite.Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability.As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g(-1) at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China [2] Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China.

ABSTRACT
LiNi0.5Mn1.5O4 nanorods wrapped with graphene nanosheets have been prepared and investigated as high energy and high power cathode material for lithium-ion batteries. The structural characterization by X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy indicates the LiNi0.5Mn1.5O4 nanorods prepared from β-MnO2 nanowires have ordered spinel structure with P4332 space group. The morphological characterization by scanning electron microscopy and transmission electron microscopy reveals that the LiNi0.5Mn1.5O4 nanorods of 100-200 nm in diameter are well dispersed and wrapped in the graphene nanosheets for the composite. Benefiting from the highly conductive matrix provided by graphene nanosheets and one-dimensional nanostructure of the ordered spinel, the composite electrode exhibits superior rate capability and cycling stability. As a result, the LiNi0.5Mn1.5O4-graphene composite electrode delivers reversible capacities of 127.6 and 80.8 mAh g(-1) at 0.1 and 10 C, respectively, and shows 94% capacity retention after 200 cycles at 1 C, greatly outperforming the bare LiNi0.5Mn1.5O4 nanorod cathode. The outstanding performance of the LiNi0.5Mn1.5O4-graphene composite makes it promising as cathode material for developing high energy and high power lithium-ion batteries.

No MeSH data available.


Related in: MedlinePlus