A Critical Review Seminar

8/3/2019 A Critical Review Seminar

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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



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.

2



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.

3



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

4



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

5



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.

6



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 ±

7



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.

8



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

9



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.

10



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.

11



Bibliography

Typographical errors

Wrong

referenceciting

Irrelevantreference

Not citingreferences

where needed

Wrong

informationabout the

references

Wrong year of publication

12



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.

13



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



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



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



Alternative InterpretationsAlternative Interpretations

y Comparison of nanowires with nanoparticle but not

with nanotubes

y

Need for further research.

17



ConclusionsConclusions

y Work could not clearly explain as to with what the

comparisons where made

18



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

19



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.

Funct. Mater., 17, 2855-2861, 2007.y

Bhushan B., µSpringer Handbook of nanotechnology¶,40-115, 200720

A Critical Review Seminar

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