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A critical review presentationA critical review presentationonon
Porous Porous ZnCo ZnCo22OO44 Nanowires Nanowires Synthesis via Synthesis via Sacrificial Templates: High Performance Sacrificial Templates: High Performance
Anode Materials of Li Anode Materials of Li--Ion Batteries Ion Batteriesbyby
Anita G SharmaAnita G SharmaUnder GuidanceUnder Guidance
of of
Prof.Prof. G.D.YadavG.D.Yadav1
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IntroductionIntroduction::
y Li-Ion battery: Need for improvement in capacity
and efficiency
y Use of transition metal oxides
y Development of environmental friendly metal oxides
y Development of one dimensional nanostructured
metal oxides for improvement in electrochemical performance.
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Experiment:Experiment:
y Development of a microemulsion based technique by
using reagents CTAB (1 gram)
(Cetyltrimethylammonium bromide) Cyclohexane
(35 mL) n-Pentanol (1.5 mL) 1 M H2C2O4 (2mL)aqueous solution Mixture of 0.05M Zn(NO3) and 0.1
M Co(NO3)2 (1.25mL)
y Template obtained: ZnCo2 (C2O4)3
y Precipitates heated at 500-700 oC for three hours to
obtain final product.
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I
mportant features of the paperI
mportant features of the papery Production of 1D nanowires via a sacrificial template
using microemulsion technique with well controlled
dimensions.
y Porous 1D nanowires with large surface area were
responsible for superior performance.
y Surface of nanowires formed were smooth with no
isolated nanoparticles.y Reversible capacities of nanowires were higher than
nanoparticles
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y Porous nanowires synthesized at 500oC showed
larger capacity and better cycling performance thanat 700oC because of larger surface area and high
porosity.
y Initial coulombic efficiency was 82% which was due
to formation of Solid electrolyte interphase film
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Literature surveyLiterature surveyy Replacement of carbon anodes with transition metal
oxides.
y Need for organizing nanomaterial on a template.
y Different oxides that can be used as anode materialfor Li-ion batteries(e.g. silicon oxide, manganeseoxide, iron oxide, cobalt oxide & nickel oxide)
y Nanotubes one of the promising structures for Li-Ion
batteries but initial Coulombic efficiency of around70%.
y Spinel structure for nanowires used as they act asefficient catalysts.
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y ZnCo2O4 as an attractive material for anode material
of Li-Ion batteries.y Chemical Reactions:
ZnCo2O4 + 8Li++8e ± Zn+ 2Co + 4 Li2O
Zn + Li++e ± LiZn
Zn + Li2OZnO+ 2Li++2e ±
2Co + 2Li2O2CoO+ 4Li++4e ±
2CoO+ 2/3Li2O2/3Co3O4 + 4/3Li++ 4/3e ±
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OriginalityOriginalityy Work done is modification and extension to the other
researches carried out.
y Modification is the synthesis of ZnCo2O
4nanowires
at different annealing temperatures.
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AssumptionsAssumptions
y Large surface area of 1D nanowires responsible for
good performance and high capacity.
y Higher surface area at 500oC due to smaller diameters and larger quantities of nanocrystals and
nanopores.
y ZnCo2O4 nanowires give superior performance in
comparison to ZnCo2O4 nanoparticles
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Technical correctnessT
echnical correctnessy Microemulsion technique with advantage of
Biocompatibility and biodegradability.
y No fact supporting the statement that ZnCo2O4
nanowires have better capacity compared to ZnCo2O4nanoparticles.
y Effect of temperature on morphology is discussed buteffect of time is not discussed.
y Some typographical errors like Colombic efficiencyinstead of Coulombic efficiency.
y Difficulty in synthesizing Spinel structure.
y Aging and annealing of precipitates formed bymicroemulsion.
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y The apparatus used is not mentioned.
y
Substrate used not mentioned.y No sample treatment done with variation of aging
times and different CTAB concentration.
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Bibliography
Typographical errors
Wrong
referenceciting
Irrelevantreference
Not citingreferences
where needed
Wrong
informationabout the
references
Wrong year of publication
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Title/abstractTitle/abstract
y Abstract same as that of conclusions.
y Title inappropriate as it does clearly define the
process
y Title mentions the use of sacrificial templates but the
use of only one template is made.
y Suitable title suggested´ ZnCo2O4 synthesis by
annealing ZnCo2 (C2O4)3 template; used as anode inLi-Ion batteries.
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Illustrations and tablesIllustrations and tables
y Too many figures when things can be made clear by
a few figures.
Figure showing XRD pattern of product prepared by
calcination of ZnCo2 (C2O4)3 . The x-axis of the
graph does not specify units used 14
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The graph depicts voltammogram curves of electrodes
made from ZnCo2O4. Herein the x-axis of the graph is not
defined which makes the validity of the plot unsure.15
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Above is a plot of capacity versus cycle number for porous
ZnCo2O4 synthesized at 500 & 700 oC.
There is a slight increase in the capacity after 5-6 cycles and
then the capacity fairly remains a constant. This slight
increase in value is not clarified16
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Alternative InterpretationsAlternative Interpretations
y Comparison of nanowires with nanoparticle but not
with nanotubes
y
Need for further research.
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ConclusionsConclusions
y Work could not clearly explain as to with what the
comparisons where made
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R eferences:R eferences:
y Poizot P., Laruelle S., Grugeon S., Dupont L., Tarascon J
M., Nature Volume 407,y 496-499, 2000y Lee H.W., Muralidharan P., Ruffo R., Mari C M., Cui Y.,
Kim D K., Nano Lett., 3852-3856, 2010.y Murphy C J., Science Volume 298, 2139-2141, 2002.
y Arico A S., Bruce P., Scrosati B., Tarascon J M., Schalkwijk WV., Nature Materials 4, 366-375, 2005.
y Nam K. T., Kim D.W., Yoo P. J., Chiang C Y., Meethong N. L., Hammond P T., Chiang Y M., Belcher A. M.,Science, 312, 885-888, 2006.
y
Cao M., Hu C.,Wang E., J Am. Chem. Soc., 11196-11197,2003.y Chan C K., Peng H L., Liu G., Mcilwrath K., Zhang X F.,
Huggins R. A., Cui Y., Nature Nanotechnology, 3, 31-34,2008
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y Yu Y., Chen C H., Shui J L., Xie S., Angew. Chem., Int. Ed.44,7085-7089,2005
y LiWY., Xu L N., Chen J., Adv. Funct. Mater., 15, 851-856, 2005.y Du N., Zhang H., Chen B D.,Wu J B., Ma X Y., Liu Z H., Zhang Y.
Q., Yang D R., Huang X H., Tu J P., Adv. Mater., 19, 4505-4509,2007
y Wang G., Gao X. P., Shen PW., J. Power Sources, 192, 719-723,2009.
y Kang Y M., Kim K T., Kim J H., Kim H S., Lee P S., Lee J Y., Liu
H K., Dou S X , J. Power Sources, 133, 252-259, 2004y Chu Y Q., Fu ZW., Qin Q Z., Electrochim. Acta., 49, 4915-4921,
2004.y Wei X H., Chen D H., TangW J., Mater. Chem. Phys., 103, 54-58,
2007y Ai C C., Yin M C.,Wang CW., Sun J T., J. Mater. Sci., 39, 1077-
1079, 2004y Fan H J., Knez M., Scholz R., Nielsch K., Pippel E., Hesse D.,
Zacharias M., Gosele U., Nat. Mater, 5, 627-631, 2006y Shamara Y., Shamara N., Rao., G V S., Chowdari B. V., R. Adv.
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Bhushan B., µSpringer Handbook of nanotechnology¶,40-115, 200720