Nano SIMS characterization of boron- and aluminum-coated LiNi1/3Co1/3Mn1/3O2 cathode materials for lithium secondary ion batteries

Abstract

The LiNi1/3Co1/3Mn1/3O2 powders required for the present study, obtained by coprecipitation method has been surface coated with boron and aluminum. The morphology and crystal structure of powders have been characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy techniques. The elemental distribution of the coated samples analyzed by transmission electron microscopy images and nano secondary ion mass spectrometry indicates a thin uniform layer of [B, Al]2O3 on the surface of spherical LiNi1/3Co1/3Mn1/3O2. The surface-modified LiNi1/3Co1/3Mn1/3O2 has been explored as a cathode material for lithium secondary ion battery applications. The electrochemical charge–discharge results reveal that the capacity retention rate of coated LiNi1/3Co1/3Mn1/3O2 after 40 cycles at 1 C rate maintains 93% of the initial discharge capacity while the rate of bare LiNi1/3Co1/3Mn1/3O2 maintains only 88%. It is noticed that the small amounts of boron and aluminum coatings on the surface of LiNi1/3Co1/3Mn1/3O2 can significantly improve the electrochemical properties of electrode materials because of the suppression of reaction between the cathode and the electrolytes.

Full text

1 23
Journal of Applied Electrochemistry
ISSN 0021-891X
Volume 42
Number 1
J Appl Electrochem (2012) 42:41-46
DOI 10.1007/s10800-011-0369-x
Nano SIMS characterization of boron- and
aluminum-coated LiNi1/3Co1/3Mn1/3O2
cathode materials for lithium secondary ion
batteries
Tae Eun Hong, E.D.Jeong, S.R.Baek,
M.R.Byeon, Young-Suck Lee, F.Nawaz
Khan & Ho-Soon Yang

1 23
Your article is protected by copyright and
all rights are held exclusively by Springer
Science+Business Media B.V.. This e-offprint
is for personal use only and shall not be self-
archived in electronic repositories. If you
wish to self-archive your work, please use the
accepted author’s version for posting to your
own website or your institution’s repository.
You may further deposit the accepted author’s
version on a funder’s repository at a funder’s
request, provided it is not made publicly
available until 12 months after publication.

ORIGINAL PAPER
Nano SIMS characterization of boron- and aluminum-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
cathode materials for lithium secondary
ion batteries
Tae Eun Hong •E. D. Jeong •S. R. Baek •
M. R. Byeon •Young-Suck Lee •F. Nawaz Khan •
Ho-Soon Yang
Received: 2 September 2011 / Accepted: 4 November 2011 / Published online: 7 December 2011
ÓSpringer Science+Business Media B.V. 2011
Abstract The LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders required for
the present study, obtained by coprecipitation method has
been surface coated with boron and aluminum. The mor-
phology and crystal structure of powders have been
characterized using scanning electron microscopy, X-ray
diffraction and X-ray photoelectron spectroscopy tech-
niques. The elemental distribution of the coated samples
analyzed by transmission electron microscopy images and
nano secondary ion mass spectrometry indicates a thin
uniform layer of [B, Al]
2
O
3
on the surface of spherical
LiNi
1/3
Co
1/3
Mn
1/3
O
2
. The surface-modified LiNi
1/3
Co
1/3
Mn
1/3
O
2
has been explored as a cathode material for lith-
ium secondary ion battery applications. The electrochem-
ical charge–discharge results reveal that the capacity
retention rate of coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
after 40
cycles at 1 C rate maintains 93% of the initial discharge
capacity while the rate of bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
maintains only 88%. It is noticed that the small amounts
of boron and aluminum coatings on the surface of LiNi
1/3
Co
1/3
Mn
1/3
O
2
can significantly improve the electrochem-
ical properties of electrode materials because of the
suppression of reaction between the cathode and the
electrolytes.
Keywords Lithium secondary ion battery Cathode
material Lithium-nickel-cobalt-manganese oxide 
Electrochemical properties Nano secondary ion mass
spectrometry
1 Introduction
Recently, rechargeable lithium-ion batteries have found
their way into portable electronic devices and in other
fields including automotive applications [1–5]. Recharge-
able lithium-ion batteries have mainly utilized the LiCoO
2
as the cathode material because of the simplicity of pro-
duction and stable cycling performance [6]. However,
LiCoO
2
has its own limitation due to the toxicity and the
high cost of cobalt, and the poor thermal stability when it is
fully charged. In search of highly improved cathode mate-
rials for the lithium-ion battery applications, various systems,
such as carbon-coated LiFePO
4
cathode [7], Al
2
O
3
-and
AlF
3
-coated LiFePO
4
cathode [8], chitosan-added LiFePO
4
cathode [9], and LiCoO
2
cathodes [10,11], are reported.
The LiNi
1/3
Co
1/3
Mn
1/3
O
2
materials have been recently
utilized as an alternative substitute to conventional LiCoO
2
cathodes in lithium battery applications because of their
advantages, such as high capacity [6,12], relatively good
rate capability [13,14], and enhanced safety [15–18].
However, the insufficient rate capability still limits their
further applications. The studies of these mixed transition
T. E. Hong E. D. Jeong S. R. Baek M. R. Byeon
Busan Center, Korea Basic Science Institute,
Busan 618-230, Korea
T. E. Hong (&)H.-S. Yang
Department of Physics, Pusan National University,
Busan 609-735, Korea
e-mail: tehong@kbsi.re.kr
H.-S. Yang
e-mail: hsyang@pusan.ac.kr
Y.-S. Lee
Interdisciplinary School of Green Energy, Ulsan National
Institute of Science and Technology, Ulsan 689-798, Korea
F. N. Khan
School of Advanced Sciences, VIT University,
Tamil Nadu 632-014, India
123
J Appl Electrochem (2012) 42:41–46
DOI 10.1007/s10800-011-0369-x
Author's personal copy

metal oxides reveal that only the trivalent cobalt plays a
more active redox role in the later stages of lithium
removal than the divalent nickel and the tetravalent man-
ganese, by virtue of its being predominantly electrochem-
ically active. However, all these layered oxides have their
inherent thermodynamic instabilities upon lithium
removal; hence, their kinetic instabilities can create prob-
lems if there is any thermal excursion in the electro-
chemical cell. The stability can, however, be improved
with aluminum substitution.
There are several methods of improving the electro-
chemical properties of electroactive materials, such as
covering electrode material surfaces with conductive sur-
face coating [19–24], and doping with metals which
improves the stability of electrode by rising electronic
conductivity, and deflating polarization [25–32]. Since the
energy density of batteries is very sensitive to the particle
shape and size of cathode materials, it is believed that the
surface coating is a useful and easy way to improve the
electrochemical properties of cathode materials [19–24].
Many investigations have reported that surface-coating
approach is an effective way to improve the electrochem-
ical properties of cathode materials [16,17]. Based on the
facts mentioned above, the present study envisions the
coating electroactive materials, LiNi
1/3
Co
1/3
Mn
1/3
O
2
,
with a trivalent oxide of [B, Al]
2
O
3
for the enhancement
of electrochemical properties. In this study, the surface
modification using boron and aluminum elements to sta-
bilize the surface of LiNi
1/3
Co
1/3
Mn
1/3
O
2
has been
explored. LiNi
1/3
Co
1/3
Mn
1/3
O
2
powder has been obtained
by coprecipitation method, and the effect of the surface
modification of LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders is discussed.
2 Experimental
The (Ni
1/3
Co
1/3
Mn
1/3
)(OH)
2
has been prepared from
NiSO
4
, CoSO
4
, and CoSO
4
by coprecipitation [18,33–36].
The obtained (Ni
1/3
Co
1/3
Mn
1/3
)(OH)
2
powders were then
dried at 120 °C for 12 h. In order to prepare the LiNi
1/3
Co
1/3
Mn
1/3
O
2
powder, the (Ni
1/3
Co
1/3
Mn
1/3
)(OH)
2
and Li
2
CO
3
at a molar ratio of 1:1.03 were mixed thoroughly and heated
to 900 °C for 10 h in air. The surface of LiNi
1/3
Co
1/3
Mn
1/3
O
2
corresponding to 0.2 mol was coated with boron
(B) and aluminum (Al) by mixing 0.1 mol of the aluminum
isopropoxide and 0.03 mol of boron trifluoridediethyl
etherate dissolved in 100 ml of ethanol at ambient condi-
tion. It was then dried at 100 °C for 6 h and heated up to
700 °C for 10 h. The morphology and crystal structure of
the coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders were character-
ized using a scanning electron microscope (SEM; Nano-
Sem 230, USA), X-ray diffractometry (XRD; Rigaku
D/Max-2200V, Japan) X-ray photoelectron spectrometer
(XPS; Escalab 250, UK) and transmission electron
microscopy (TEM; JEM2011, Japan).
Nano secondary ion mass spectrometry equipped with a
cesium gun (Nano SIMS; Cameca Nano-SIMS 50, France)
having spatial resolution of 50 nm which is superior to
other dynamic SIMS is employed to analyze the compo-
sition and spatial distribution of elements on the surface
and the cross section of materials. The experimental data
were obtained in multi collection detector mode by sput-
tering the sample with a *1pACs
?
primary ion beam
focused into a spot of *100 nm diameter. The primary
ion beam was rastered over 20 920 lm
2
. Samples were
coated with gold for charge compensation, and a
pre-sputtering of the surface was performed before any
measurements to remove the surface contamination of
gold-coated layer. The powders were also mounted using
epoxy resin and then polished with SiC paper to measure
the element distribution on the cross section of the coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders.
The charge–discharge characteristics of LiNi
1/3
Co
1/3
Mn
1/3
O
2
cathodes have been investigated in CR2016 coin-
type half cells. The coin-type half cell 2016-size contained
a test electrode, a lithium-metal counter-and-reference
electrode, a 15-lm-thick microporous polyethylene sepa-
rator, and an electrolyte solution of 1.15 M LiPF
6
in eth-
ylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl
carbonate (DEC) (3:4:3 vol.%) (LG Chem., Korea). The
amount of active materials in the cathode composite was
20 mg. The cathodes for the battery test cell were made
from the cathode materials, super P carbon black, and
polyvinylidene fluoride (PVdF) binder (Solef) in a weight
ratio of 94:3:3. The electrodes were prepared by coating a
cathode-slurry onto an Al foil followed by drying at 130 °C
for 20 min, and finally subjected to a roll-pressing.
3 Results and discussion
Figure 1a, b represent the SEM images of the bare and the
surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
, respectively. The bare
LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders show round shapes with the
10–15 lm size. The SEM images reveal the surface-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
remains unaltered even after the surface-
coating process, but the particle size is increased by about 1 lm.
The XRD patterns of the bare and the surface-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders are presented in Fig. 2a, b,
respectively. All the observed diffraction lines correspond
to those of a a-NaFeO
2
layered structure with a space
group of R-3m [37–40]. The lattice parameter aobtained
from Fig. 2is 2.863 A
˚for the both samples, and the cal-
culated lattice parameter cis 14.242 and 14.260 A
˚for the
bare and the coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
, respectively.
These results suggest that the crystal structure of LiNi
1/3
42 J Appl Electrochem (2012) 42:41–46
123
Author's personal copy

Co
1/3
Mn
1/3
O
2
is not affected significantly by the surface
coating.
The Ni and Mn distributions as well as those of boron and
aluminum were examined by means of Nano SIMS 50
having spatial resolution of 100 nm. Figure 3a, b shows the
elemental distributions (B, Al, Ni, and Mn) on the surface
and the cross section of the surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders, respectively. The distributions of B and
Al elements are given in the left and the right images,
respectively, at the top in each of (a) and (b), and reveal that
these elements are distributed only on the surface of the
LiNi
1/3
Co
1/3
Mn
1/3
O
2
. The chemical composition of boron
and aluminum elements on the surface was explored by
X-ray photoelectron spectroscopy measurements (Fig. 4).
The core-level spectra analysis reveals that the boron forms
B
2
O
3
and aluminum forms Al
2
O
3
. Nano SIMS images on
the cross section of the surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders show that the thickness of coated layer is about
0.7 lm. The distribution of Ni and Mn elements given in the
left and the right images, respectively, at the bottom in each
of (a) and (b) show that Ni and Mn elements are distributed
uniformly throughout the LiNi
1/3
Co
1/3
Mn
1/3
O
2
particles as
desired. It is worth to mention that in enhancing the elec-
trochemical properties, it is important to have dense coating.
In Fig. 3b, the Nano SIMS image shows that the coverage of
the coating is uniformly distributed throughout the entire
surface, even though there is slight variation of the intensity
of the coated material. Furthermore, TEM observation
(Fig. 5) also showed the existence of the the fully covered
dense coating.
The capacity–voltage curves for the first cycle of the
bare and surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
, respectively,
as the cell voltages are changed from 3.0 to 4.5 V at a
constant current density, are shown in Fig. 6a, b. The
curves were obtained at the charge–discharge rates of 0.1,
0.2, 0.5, and 1.0 C for each sample. The discharge capac-
ities of the bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
corresponding to 0.1,
0.2, 0.5, and 1.0 C were 181, 177, 166 and 152 mAhg
-1
,
respectively. Similar to the bare sample, the surface-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
exhibits the discharge capacities of
182, 177, 163, and 149 mAhg
-1
corresponding to 0.1, 0.2,
0.5 and 1 C, respectively. Previously, Huang et al. [37]
reported that the initial discharge-specific capacities in
LiNi
1/3
Co
1/3
Mn
1/3
O
2
at 0.1, 0.5, 1, and 2 C were 153, 140,
130 and 118 mAhg
-1
, respectively. The discharge capac-
ities of the both samples are significantly improved com-
pared with the previous reported results of LiNi
1/3
Co
1/3
Mn
1/3
O
2
materials [38–40].
Figure 7shows the capacity as a function of cycle
numbers for the bare and the surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
. As the cycle of charge–discharge repeats at a rate
of 1.0 C, the discharge capacity decreases. However, the
variation of capacity as the number of cycle increases is
different between the bare and surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
powers. The retention capacity of bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
after 40 cycles is 88% of initial capacity, but
the retention capacity of the surface-coated LiNi
1/3
Co
1/3
Fig. 1 SEM images of (a) bare and (b) [B, Al]
2
O
3
-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
powder
20 30 40 50 60 70
(a)
(b)
2 theta / Deg.
Intensity / a.u.
(003)
(101)
(006)/(102)
(104)
(105)
(107)
(018)
(110)
(113)
Fig. 2 X-ray diffraction patterns of (a) bare and (b) [B, Al]
2
O
3
-
coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
J Appl Electrochem (2012) 42:41–46 43
123
Author's personal copy

Mn
1/3
O
2
improves to 93%. Even though there is no sig-
nificant difference in the irreversible capacity loss between
the bare and the surface-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
.
194 192 190 188
160
180
200
220
B1s raw data
B
2
O
3
curve fit
B2O3
Intensity / a.u.
Binding Energy / eV
(a)
(b)
80 75 70 65
100
200
300
400
Al
2
O
3
Al2p raw data
Al
2
O
3
curve fit
Ni3p curve fit
Ni3p
Intensity / a.u.
Binding Energy (eV)
Fig. 4 X-ray photoelectron spectra of (a) B1s and (b) Al2p on the
surface of [B, Al]
2
O
3
-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
Fig. 5 Transmission electron microscopy image of [B, Al]
2
O
3
-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
Fig. 3 Elemental distributions of B, Al, Mn, and Ni on (a) the surface
and (b) the cross section of [B, Al]
2
O
3
-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
obtained by Nano SIMS. The left and the right images at the top in
both (a) and (b) are the distributions of B and Al, respectively, and the
left and the right images at the bottom are the distributions of Mn and
Ni, respectively
44 J Appl Electrochem (2012) 42:41–46
123
Author's personal copy

4 Conclusions
Spherical LiNi
1/3
Co
1/3
Mn
1/3
O
2
powders forming in a a-
NaFeO
2
crystal structure were synthesized with coprecipi-
tation method. The surface of LiNi
1/3
Co
1/3
Mn
1/3
O
2
powder
was coated successfully with boron and aluminum. The thin
and uniform [B, Al]
2
O
3
layer is observed on the surface of
LiNi
1/3
Co
1/3
Mn
1/3
O
2
by Nano SIMS. There is significant
improvement in the initial discharge specific capacities of
both bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
and [B, Al]
2
O
3
-coated
LiNi
1/3
Co
1/3
Mn
1/3
O
2
compared with the results of others.
Although the coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
has no significant
difference in initial discharge capacity, the capacity reten-
tion is improved compared with bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
.
The enhancement of retention capacity is attributed to the
improvement in the charge transfer kinetics and the stability
in electrolyte due to [B, Al]
2
O
3
coating. We confirm that a
thin coating of boron and aluminum on surface of LiNi
1/3
Co
1/3
Mn
1/3
O
2
can significantly improve the electrochemi-
cal properties as an electrode material.
Acknowledgment This study was supported by KBSI Grant
(T31601) to T. E. Hong.
References
1. Scrosati B (1995) Nature 373:557
2. Tarascon JM, Armand M (2001) Nature 414:359
3. Guyomard D (2000) New trends in electrochemical technology:
energy storage systems for electronics. Gordon & Breach Science
Publishers, New York
4. Wakihara W, Yamamoto O (1998) Lithium ion batteries—fun-
damentals and performance. Kodansha-Wiley-VCH, Weinheim
5. Bruce PG, Scrosti B, Tarascon JM (2008) Angew Chem Int Ed
47:2930
6. Antolini E (2004) Solid State Ionics 170:159
7. Jeong ED, Kim HJ, Ahn CW, Ha MG, Hong TE, Kim HG, Jin JS,
Bae JS, Hong KS, Kim YS, Kim HJ, Doh CH, Yang HS (2009)
J Nanosic Nanotechnol 9:4467
8. Ahn CW, Ha MG, Hong KS, Lee DJ, Doh CH, Doh KY, Na JM,
Song BH, Jeon HM, Cho YG, Yang HS, Jeong ED (2010) Defect
Diffus Forum 297:906
9. Hong KS, Yu SM, Ha MG, Ahn CW, Hong TE, Jin JS, Kim HG,
Jeong ED, Kim YS, Kim HJ, Doh CH, Yang HS, Jung H (2009)
Bull Korean Chem Soc 30:1719
10. Cho PJ, Jeong ED, Shim YB (1998) Bull Korean Chem Soc 19:39
11. Jeong ED, Won MS, Shim YB (1998) J Power Sources 70:70
12. Stewart SG, Srinivasan V, Newman J (2008) J Electrochem Soc
155:A664
13. He SS, Ma ZF, Liao XZ, Jiang Y (2007) J Power Sources
163:1053
14. Martha SK, Markevich E, Burgel V, Salitra G, Zingigrad E,
Markovsky B, Sclar H, Pramovich Z, Heik O, Aurbach D, Exnar
I, Buqa H, Drezen T, Semrau G, Schmidt M, Kovacheva D,
Saliyski N (2009) J Power Sources 189:288
15. Martha SK, Sclar H, Framowitz ZS, Kovacheva D, Saliyski N,
Gofer Y, Sharon P, Golik E, Markovsky B, Aurbach D (2009)
J Power Sources 189:248
16. Ohzuku T, Makimura Y (2001) Chem Lett 7:642
17. Yabuuchi N, Ohzuku T (2003) J Power Sources 119:171
18. Kim J, Park C, Sun Y (2003) Solid State Ionics 164:43
19. Huang SH, Wen ZY, Zhang JC, Gu ZH, Xu XH (2006) Solid
State Ionics 177:851
20. Dominko R, Gaberscek M, Bele U, Mihailovic D, Jamnik J
(2007) J Eur Ceram Soc 27:909
21. Liu H, Feng Y, Wang K, Xie JY (2008) J Phys Chem Solids
69:2037
22. Huang JJ, Jiang ZY (2008) Electrochim Acta 53:7756
0 60 120 180 240
3.0
3.5
4.0
4.5
Cell Potential (V)
Capacity(mAh/g)
(a)
(b)
0.1C
0.2C
0.5C
1C
0 60 120 180 240
3.0
3.5
4.0
4.5
Cell Potential (V)
Capacity(mAh/g)
0.1C
0.2C
0.5C
1C
Fig. 6 Capacity–voltage curves of (a) bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
(b) [B, Al]
2
O
3
-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
for the initial cycle at the
charge–discharge rates of 0.1, 0.2, 0.5, and 1.0 C
0 10203040
120
130
140
150
160
170
Cycle Number
Capacity /mAh g
-1
Bare
[B,Al]O
3
coated
Fig. 7 Cycle performances of bare LiNi
1/3
Co
1/3
Mn
1/3
O
2
and [B,
Al]
2
O
3
-coated LiNi
1/3
Co
1/3
Mn
1/3
O
2
at a 1.0 C rate in lithium half
cells
J Appl Electrochem (2012) 42:41–46 45
123
Author's personal copy

23. Yang LZ, Gao LJ (2009) J Alloys Comp 485:93
24. Wolfenstine J, Lee U, Allen JL (2006) J. Power Sources 154:287
25. Liu DT, Quyang CY, Shu J, Jiang J, Wang ZX, Chen LQ (2006)
Phys Stat Sol (b) 243:1935
26. Hao YJ, Lai QY, Lu JZ, Ji XY (2007) Ionics 13:369
27. Kubiak P, Garcia A, Womes M, Aldon L, Olivier-Fourcade J,
Lippens PE, Jumas JC (2003) J Power Sources 119:626
28. Huang SH, Wen ZY, Gu ZH, Zhu XJ (2005) Electrochim Acta
50:4057
29. Huang SH, Wen ZY, Zhu XJ, Lin ZX (2007) J Power Sources
165:408
30. Yu HY, Zhang XF, Jalbout AF, Yan XD, Pan XM, Xie HM,
Wang RS (2008) Electrochim Acta 53:4200
31. Tabuchi T, Yasuda H, Yamachi M (2006) J Power Sources 162:813
32. Wolfenstine J, Allen JL (2008) J Power Sources 180:582
33. Wu Y, Manthiram A (2009) Solid State Ionics 180:50
34. Liu J, Manthiram A (2009) Chem Mater 21:1695
35. Lee MH, Kang YJ, Myung ST, Sun YK (2004) Electrochem Acta
50:939
36. Cho TH, Park SM, Yoshio M (2004) Chem Lett 700
37. Huang ZD, Liu XM, Zhang B, Oh S, Ma PC, Kim JK (2011)
Scripta Mater 64:122
38. Kim GH, Myung ST, Kim HS, Sun YK (2006) Electrochim Acta
51:2447
39. Chang Z, Chen Z, Wu F, Tang H, Zhu Z, Yuan ZZ, Wang H
(2008) Electochim Acta 53:5927
40. Zhang S, Deng C, Fu BL, Yang SY, Ma L (2010) Powder
Technol 198:373
46 J Appl Electrochem (2012) 42:41–46
123
Author's personal copy