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Facile solvothermal synthesis of mesoporous
manganese ferrite (MnFe2O4) microspheres as
anode materials for lithium-ion batteries
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Journal of Colloid and Interface Science
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DOI: 10.1016/j.jcis.2013.01.067
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Facile solvothermal synthesis of mesoporous manganese ferrite (MnFe 2O4)
microspheres as anode materials for lithium-ion batteries
Zailei Zhanga, Yanhong Wanga,⇑, Qiangqiang Tana, Ziyi Zhongb, Fabing Sua,⇑
aState Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
bInstitute of Chemical Engineering and Sciences, A ⁄Star, 1 Pesek Road, Jurong Island, Singapore 627833, Singapore
article info
Article history:
Received 19 November 2012
Accepted 28 January 2013Available online 16 February 2013
Keywords:
Mesoporous manganese ferritemicrospheresAnode materialsElectrochemical propertiesLi-ion batteriesabstract
We report the synthesis and characterization of the mesoporous manganese ferrite (MnFe 2O4) micro-
spheres as anode materials for Li-ion batteries. MnFe 2O4microspheres were synthesized by a facile solvo-
thermal method using Mn(CH 3COO) 2and FeCl 3as metal precursors in the presence of CH 3COOK,
CH3COOC 2H5, and HOCH 2CH2OH. The samples were characterized by X-ray diffraction, transmission elec-
tron microscopy, scanning electron microscopy, nitrogen adsorption, thermal gravimetric, X-ray photo-electron spectroscopy, temperature programmed reduction, and temperature programmed oxidation.The synthesized mesoporous MnFe
2O4microspheres composed of nanoparticles (10–30 nm) were
100–500 nm in diameter and had surface areas between 60.2 and 86.8 m2g/C01, depending on the CH 3-
COOK amounts added in the preparation. After calcined at 600 /C176C, MnFe 2O4was decomposed to Mn 2O3
and Fe 2O3mixture. The mesoporous MnFe 2O4microspheres calcined at 400 /C176C showed a capacity of
712.2 mA h g/C01at 0.2 C and 552.2 mA h g/C01at 0.8 C after 50 cycles, and an average capacity fading rate
of around 0.28%/cycle and 0.48%/cycle, much better than those of the samples without calcination andcalcined at 600 /C176C. The work would be helpful in the fabrication of binary metal oxide anode materials
for Li-ion batteries.
/C2112013 Elsevier Inc. All rights reserved.
1. Introduction
In recent years, with the increase in portable electronic devices
and upcoming electric vehicles, the demand for rechargeable lith-
ium-ion (Li-ion) batteries has become significantly increased [1–4] .
It is essential to develop electrode materials with low cost, high en-
ergy density, durability, and safety [5,6] . Transition-metal oxides
(TMOs, here TM = Mn, Co, Fe, Ni, Cu, etc.) are the promising high-
performance anode materials for the next generation of Li-ion bat-
teries because of their much higher lithium-storage capacities than
that of the commercially used graphite, as well as their safer nat-
ure, environmental benignity, and low cost [7,8] . Many nanostruc-
tured TMOs such as Co 3O4nanowires [9], hierarchical NiO spheres
[10], hollow TiO 2spheres [11], porous CuO nanostructures [12],
mesoporous MnO 2[13], porous Fe 3O4[14], porous Fe 2O3[15],
and hollow Fe 2O3spheres [16] show good electrochemical perfor-
mance, because the porous structure of these materials can bufferthe large volume change of anodes during the conversion reaction
and the repeated Li
+insertion/extraction, thus alleviating the pul-
verization problem and enhancing the cycling performance. As a
result, nanostructured binary metal oxides, including double-shelled hollow CoMn 2O4microcubes [17], porous ZnCo 2O4nano-
tubes [18], hollow ZnMn 2O4microspheres [19], core-shell
Mn 1.5Co1.5O4microspheres [20], and NiCo 2O4spinel [21], have at-
tracted great attention for Li-ion batteries, and they indeed exhibit
superior electrochemical lithium-storage performances with high
specific capacity, good cyclability, and excellent rate capability.
As one of binary metal oxides, manganese ferrite (MnFe 2O4)
with various morphologies has been fabricated, such as spinel
nanocrystals [22], monodispersed nanocrystals [23], nanocubes
[24], and hollow spheres [25]. This kind of material can be used
in magnetic devices [26], supercapacitor [27], drug delivery [28],
and synthetic wastewater [29]. However, to our knowledge, as an
anode materials, MnFe 2O4has not been explored although it can
store Li+through the conversion reaction (MnFe 2O4+ 8Li++8 e/C0-
MMn + 2Fe + 4Li 2O) and has a high theoretical capacity of
928 mA h g/C01, which is much higher than that of graphite anode
(375 mA h g/C01). On the other hand, micrometer-sized materials
with a spherical morphology are actually the optimal material
morphology in conventional electrode fabrication art, because
microspheres have high packing density for high volumetric en-
ergy and power density, and good particle mobility to form a uni-
formly compact electrode layer. As we know, most of the spherical
graphite anode materials such as spherical graphite [30], spherical
carbon-coated natural graphite [31], spherical silicon/graphite/car-
bon composites [32], and flake graphite/silicon/carbon spherical
0021-9797/$ – see front matter /C2112013 Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.jcis.2013.01.067⇑Corresponding authors. Fax: +86 10 82544851 (F. Su).
E-mail addresses: wangyanhong@mail.ipe.ac.cn (Y. Wang), fbsu@mail.ipe.ac.cn
(F. Su).Journal of Colloid and Interface Science 398 (2013) 185–192
Contents lists available at SciVerse ScienceDirect
Journal of Colloid and Interface Science
www.elsevier.com/locate/jcis

composite [33] show high coulombic efficiency and high rate
capacity. Therefore, it will be ideal to prepare porous MnFe 2O4
materials with spherical morphology as anodes for Li-ion batteries.
Herein, we report the synthesis of mesoporous MnFe 2O4micro-
spheres via a facile solvothermal method. The as-synthesized
MnFe 2O4materials are assemblage of nanoparticles, and the high
temperature calcination at 600 /C176C leads to the decomposition of
MnFe 2O4into Fe 2O3and Mn 2O3. The mesoporous MnFe 2O4micro-
spheres calcined at 400 /C176C exhibit the highest capacity and cyclic
stability.
2. Experimental
2.1. Material synthesis
All the chemicals were of analytical grade and purchased from
Sinopharm Chemical Reagent Co., Ltd. In a typical synthesis,
0.5 mmol manganese (II) acetate tetrahydrate (Mn(CH 3COO) 2/C14H2-
O, A. R.), 1.0 mmol Iron (III) chloride hexahydrate (FeCl 3/C16H2O, A.
R.), and Xmmol potassium acetate trihydrate CH 3COOK /C13H2O, A.
R.) were dissolved in 40.0 mL ethylene glycol (HOCH 2CH2OH, A.
R.), and then, 2.0 mL ethyl acetate (CH 3COOC 2H5, A. R.) was added
under stirring to form a uniform solution. The mixed solution was
sealed and heated at 200 /C176C for 16 h to get the solid products. The
resulting precipitate was collected by centrifugation and washed
with distilled water and absolute ethanol and then finally dried
in vacuum at 80 /C176C for 8 h. The obtained samples with X= 0.3,
0.6, 0.9, and 1.2 mmol were denoted as MnFe 2O4-1, MnFe 2O4-2,
MnFe 2O4-3, and MnFe 2O4-4, respectively. After a further calcina-
tion of MnFe 2O4-2 at 400 /C176C or 600 /C176C for 4 h, the obtained materi-
als were named as MnFe 2O4-2-400 and MnFe 2O4-2-600,
respectively.
2.2. Characterization
The porous nature of the samples was investigated using phys-
ical adsorption of nitrogen at liquid-nitrogen temperature
(/C0196/C176C) on an automatic volumetric sorption analyzer (NO-
VA3200e, Quantachrome). Prior to the measurement, the sample
was degassed at 200 /C176C for 5 h under vacuum. The specific surface
areas were determined according to the Brunauer–Emmett–Teller
(BET) method in the relative pressure range of 0.05–0.2. Pore size
distribution (PSD) curves were derived from the Barrett–Joyner–
Halenda (BJH) method using the adsorption branches. The pore
sizes were estimated from the maximum positions of the BJH
PSD curves. X-ray diffraction patterns (XRD) were recorded on a
PANalytical X’Pert PRO MPD using the Cu K aradiation
(k= 1.5418 Å). The microscopic feature of the samples was charac-
terized by field-emission scanning electron microscopy (SEM)
(JSM-6700F, JEOL, Tokyo, Japan) and transmission electron micros-
copy (TEM) with Energy Dispersive Spectrometer (EDS) (JEM-
2010F, JEOL, Tokyo, Japan). Thermogravimetric (TG) analysis was
carried out on an EXSTAR TG/DTA 6300 (Seiko Instruments, Japan)
at a heating rate of 5 /C176C/min in air (200 mL/min). X-ray photoelec-
tron spectroscopy (XPS) analysis was carried out on an ESCA-
Lab250 electron spectrometer from Thermo Scientific Corporation
using monochromatic 150 W Al K aradiation. Pass energy for the
narrow scan was 30 eV. The chamber pressure was about
6.5/C210/C010mbar. The binding energies were referenced to the
C1s line at 284.8 eV. Temperature programmed reduction (TPR)
and temperature programmed oxidation (TPO) measurements
were carried out on an Automated chemisorption analyzer (Chem-
BET pulsar TPR/TPD, Quantachrome). A 0.10 g of sample was
loaded in a quartz U-tube. Prior to the measurement, the sample
was degassed at 200 /C176C for 30 min under He. After the temperaturedropped to 20 /C176C, the gas was changed to 9.9% H 2/Ar. Then, the
sample was heated from 20 /C176C to 800 /C176Ca t1 0 /C176C min/C01under the
flow of 9.9% H 2/Ar at 30 mL min/C01. After the temperature dropped
to 20 /C176C, the gas was changed to 9.9% O 2/Ar. Finally, the sample was
heated from 20 /C176C to 900 /C176Ca t1 0 /C176C min/C01under the flow of 9.9%
O2/Ar at 30 mL min/C01.
2.3. Electrochemical measurement
The working electrode was prepared by mixing the mesoporous
MnFe 2O4microspheres (MnFe 2O4-2, MnFe 2O4-2-400, MnFe 2O4-2-
600) with acetylene black and polyvinylidene fluoride (PVDF) in
a weight ratio of 80:10:10 using N-methylpyrrolidone (NMP) as a
solvent. The resulting slurries were cast onto copper current collec-
tors and then dried at 120 /C176C under vacuum for 12 h. The foils were
rolled into 30 lm thin sheets and then cut into disks which are
14 mm in diameter. CR2016 coin-type cells were assembled in an
Ar-filled glove box with lithium foils as the counter electrodes
and polypropylene microporous films (Celgard 2400) as separators.
The liquid electrolyte is 1 mol L/C01LiPF 6in a mixture of ethylene
carbonate (EC) and dimethyl carbonate (DMC) (1:1, v/v). The galva-
nostatic charge and discharge tests were carried out by the
CT2001A LAND testing instrument in a voltage range between
0.01 and 3.0 V at a current rate of 0.2 and 0.8 C (1C = 928 mA g/C01).
3. Results and discussion
Fig. 1 shows the SEM images of the MnFe 2O4microspheres ob-
tained at different amounts of CH 3COOK /C13H2O added. In the ab-
sence of CH 3COOK /C13H2O, no solid products are obtained. When
0.3 mmol of CH 3COOK /C13H2O is added, MnFe 2O4microspheres
(MnFe 2O4-1) with a diameter of 100–700 nm are obtained
(Fig. 1 a). Further increasing CH 3COOK /C13H2O to 0.6 mmol (MnFe 2-
O4-2 in Fig. 1 b) and 0.9 mmol (MnFe 2O4-3 in Fig. 1 c), the obtained
MnFe 2O4microspheres become smaller (100–300 nm) and more
uniform in size. In the case, when the amount of CH 3COOK /C13H2O
reaches 1.2 mmol (MnFe 2O4-4), the obtained MnFe 2O4micro-
spheres ( Fig. 1 d) become much smaller in size (100–200 nm), but
part of them have been aggregated together. In addition, it can
be seen that all these microspheres are assemblage of nanoparti-
cles with a size range between 10 and 20 nm, and the interstitial
space among these nanoparticles forms. The surface area derived
from their N 2adsorption–desorption isotherms (not shown here)
is 76.9 m2/g for MnFe 2O4-1, 86.8 m2/g for MnFe 2O4-2, 82.5 m2/g
for MnFe 2O4-3, and 60.2 m2/g for MnFe 2O4-4. Their BJH PSD curves
indicate that these MnFe 2O4microspheres contain mesopores in
the range of 10–40 nm. Therefore, the spherical size of MnFe 2O4
microspheres can be tuned by changing the amount of CH 3-
COOK /C13H2O, which is used as a mineralizer. Previous work have
demonstrated the mineralizers (such as KCl, NaCl, NaNO 3, KNO 3,
K2SO4,N a 2SO4, (NH 4)2SO4, NaF, KF, and NH 4F) play a crucial role
in particle size and morphology of CuO microspheres [34], well-de-
fined Ni microflowers and Co microspheres [35], regular hexagonal
LaF 3nanoplates [36], CdS microtower, hexagonal plate, and octa-
hedral geometry [37] synthesized via solvothermal or hydrother-
mal methods.
Fig. 2 a shows the XRD patterns of the MnFe 2O4microspheres.
Diffraction peaks at 2 hvalues of 30.0 /C176, 35.6 /C176, 43.4 /C176, 57.2 /C176, and
62.8/C176are observed, which correspond to the lattice plane of
(220), (311), (400), (511), and (440) of MnFe 2O4(JCPDS No.
003-0864), respectively, indicating formation of MnFe 2O4crystal-
lites. The EDS spectrum of MnFe 2O4-2 in Fig. 2 b demonstrates
the presence of Mn, Fe, and O with an approximate atomic ratio
of 1:2:4, consistent with that of MnFe 2O4.186 Z. Zhang et al. / Journal of Colloid and Interface Science 398 (2013) 185–192

Fig. 3 a shows the TEM image of MnFe 2O4-2. These microspheres
in the size range of 150–250 nm are mesoporous structure. Their
high-magnification TEM image in Fig. 3 b reveals that these micro-
spheres are composed of nanoparticles in the range of 10–30 nm.
The TEM image in Fig. 3 c further confirms the high crystallinity
of these nanoparticles. The lattice fringe with a spacing of
0.296 nm is assigned to the interplanar between the (220) plane
of cubic MnFe 2O4(JCPDS No. 003-0864). Accordingly, the corre-
sponding selected-area electron diffraction (SAED) pattern in
Fig. 3 d displays the discontinuous diffraction rings, suggesting that
MnFe 2O4-2 microspheres are polycrystalline.
Fig. 4 a shows the wide XPS spectra of MnFe 2O4-2, revealing the
presence of Mn, Fe, O, and C elements. The C element ( Fig. 4 a) mayoriginate from the adventitious carbon-based contaminant and/or
from the organic compounds such as residual HOCH 2CH2OH and
CH3COOC 2H5adsorbed on the surface. The binding energy of the
C 1s peak at 284.8 eV is used as the reference for calibration.
Fig. 4 b shows the Mn 2p spectrum. Two strong peaks at 641.5 eV
for Mn 2p 3/2and 653.0 eV for Mn 2p 1/2are observed, indicating
the oxidation state of Mn2+in MnFe 2O4[38].Fig. 4 c shows the Fe
2p spectrum. Two major peaks at 711.5 and 724.9 eV are ascribed
to Fe 2p 3/2and Fe 2p 1/2of Fe3+, respectively [38]. The O1s spectra in
Fig. 4 d can be fitted by three peaks: the peak at 530.1 eV is charac-
teristic of oxygen in metal oxide such as Fe–O and Mn–O (MnFe 2O4)
[18], and other two peaks at around 531.6 and 533.3 eV may be
assigned to the oxygen in H 2O and organic compunds such as
Fig. 1. SEM images of the mesoporous MnFe 2O4microspheres obtained at different CH 3COOK /C13H2O amounts: (a) 0.3 mmol (MnFe 2O4-1), (b) 0.6 mmol (MnFe 2O4-2), (c)
0.9 mmol (MnFe 2O4-3), and (d) 1.2 mmol (MnFe 2O4-4).
20 30 40 50 60 70 80MnFe2O4-4MnFe2O4-3MnFe2O4-2Intensity (a.u.)
2Theta (Degree)(440)
(511) (400)(311)
(220)MnFe2O4-1(b) (a)
Fig. 2. (a) XRD patterns of mesoporous MnFe 2O4microspheres and (b) EDS spectrum of mesoporous MnFe 2O4microspheres (MnFe 2O4-2).Z. Zhang et al. / Journal of Colloid and Interface Science 398 (2013) 185–192 187

HOCH 2CH2OH, and CH 3COOC 2H5adsorbed on the surface [39].
These XPS results indicate that the MnFe 2O4-2 sample ( Fig. 4 b)
consists of Mn, Fe, and O with an atomic ratio of Mn:Fe at 1:2.2.
The illustration of the formation process of mesoporous MnFe 2-
O4microspheres is shown in Fig. 5 . In the first stage, the Mn2+and
Fe3+ions were nucleated under solvothermal conditions via the
reaction (Mn2++ 2Fe3++4 H 2O?MnFe 2O4+8 H+) with the water
generated from metal precursors to form nanosized crystalline
MnFe 2O4. Then, in the second stage, these small nanoparticles are
self-assembled into large secondary particles. Ethylene glycol and
CH3COOC 2H5can be absorbed on the surface of the nanosized crys-
talline particles and acted as structure-directing agents to regulate
their surface state, influencing the nucleation and aggregate pro-
cess of the nanoparticles, which are finally assembled to the micro-
spheres with mesoporous structure.
Fig. 6 a shows the TG curve of the MnFe 2O4-2 microspheres. The
weight loss below 100 /C176C is about 1.16 wt.%, which is ascribed to
the desorption of physically adsorbed H 2O, while that of
8.62 wt.% from 100 to 400 /C176C is due to the decomposition of organ-
ic species, such as adsorbed HOCH 2CH2OH and CH 3COOC 2H5on the
sample surface, which was detected by XPS. In the range of 500–
700/C176C, there is a well-defined weight rise (2.08 wt.%), which is
due to the decomposition of MnFe 2O4to Fe 2O3and MnO, and fur-
ther oxidation of MnO to Mn 2O3.Fig. 6 b shows the XRD patterns of
MnFe 2O4-2, MnFe 2O4-2-400, and MnFe 2O4-2-600. Compared with
the XRD pattern of MnFe 2O4-2, after calcined at 400 /C176C, the crystal
structure of MnFe 2O4-2-400 is well maintained. However, after cal-
cined at 600 /C176C, only the peaks of Fe 2O3[40] and Mn 2O3are ob-
served, suggesting the decomposition of MnFe 2O4to Fe 2O3andMn 2O3, which may follow the reaction steps: MnFe 2O4?Fe2O3+
MnO and 4MnO + O 2?2Mn 2O3[41].Fig. 6 c shows the SEM image
of MnFe 2O4-2-400 microspheres, which also consist of MnFe 2O4
nanoparticles with a size range of 100–300 nm. Fig. 6 d shows the
SEM images of MnFe 2O4-2-600 microspheres, which should con-
tain both Fe 2O3and Mn 2O3nanoparticles, and their size is similar
to that of the MnFe 2O4-2-400 nanoparticles. Fig. 6 e and f shows
the TEM images of MnFe 2O4-2-400 and MnFe 2O4-2-600, respec-
tively. Compared with MnFe 2O4-2 with developed mesoporous
structure, MnFe 2O4-2-400 has less porous, and MnFe 2O4-2-600
has much dense and almost non-porous due to the high tempera-
ture calcination. The surface area derived from their N 2-adsorption
isotherms (not shown here) is 62.6 m2/g for MnFe 2O4-2-400 and
23.2 m2/g for MnFe 2O4-2-600, indicating the decrease in the sur-
face area after high temperature calcination. Their BJH PSD curves
indicate that their mesopores are in the range of 10–40 nm. Fig. 6 g
and h shows the H 2-TPR and O 2-TPO curves of MnFe 2O4-2, MnFe 2-
O4-2-400, and MnFe 2O4-2-600, respectively. The two maximum H 2
consumption peaks of MnFe 2O4-2 are located at about 510 and
600/C176C, respectively, while the sole O 2consumption peak ( Fig. 6 g)
of the reduced sample is located at about 513 /C176C. For MnFe 2O4-2-
400, its TPR peaks are located at about 517 and 636 /C176C, respec-
tively, and the O 2consumption peak measured in the re-oxidation
process at about 494 /C176C(Fig. 6 h). For MnFe 2O4-2-600, the main H 2
consumption peak is located at about 508 /C176C and the two O 2con-
sumption peaks at about 641 and 806 /C176C. Clearly, MnFe 2O4-2 and
MnFe 2O4-2-400 are reduced by two steps and are re-oxidized by
one step; while MnFe 2O4-2-600 (Fe 2O3and Mn 2O3composites) is
reduced by one step and re-oxidized by two steps. From the above
Fig. 3. TEM images (a–c) and SAED patterns (d) of MnFe 2O4-2.188 Z. Zhang et al. / Journal of Colloid and Interface Science 398 (2013) 185–192

results, at least we can conclude that the MnFe 2O4sample still re-
mains microsphere morphology after calcined at 400 /C176C, but it
decomposes into Fe 2O3and Mn 2O3after calcined at 600 /C176C.
The MnFe 2O4-2, MnFe 2O4-2-400, and MnFe 2O4-2-600 samples
are tested as anodes for Li-ion batteries. Fig. 7 a shows the initial
charge–discharge profiles of the electrodes made of MnFe 2O4-2,
MnFe 2O4-2-400, and MnFe 2O4-2-600 at the current density of
0.2 C. The initial discharge and charge capacities are 1086.6 and
821.5 mA h g/C01for MnFe 2O4-2, 1042.3 and 829.7 mA h g/C01for
MnFe 2O4-2-400, and 1039.6 and 669.2 mA h g/C01for MnFe 2O4-2-
600, respectively. The irreversible capacity loss of the first cycle
for metal oxides is normally attributed to the formation of theSEI film as the reported work [17]. The formation of the SEI film
usually stemmed from a catalytic-driven electrolyte reduction,
and the small metal particles have enhanced catalytic properties
[42] and therefore will favor the decomposition of the electrolyte,
resulting in the irreversible capacity loss of the first cycle and the
lifecycle failure as seen below. The initial charge–discharge capac-
ity for MnFe
2O4-2 and MnFe 2O4-2-400 is based on the oxidation–
reduction of metallic Fe and Mn nanoparticles to MnFe 2O4,
respectively: 4Li 2O + Mn + 2Fe MMnFe 2O4+ 8Li + 8e/C0. A distinctvoltage plateau can be clearly identified at ca. 0.85 V, correspond-
ing to the reduction in Fe3+to Fe and Mn2+to Mn during the initial
discharge process. Meanwhile, a defined plateau is observed in the
charge process at ca. 2.05 V, and a poorly-defined plateau is
observed in the charge process at ca. 2.25 V. The initial charge–
discharge capacity for MnFe 2O4-2-600 based on the oxidation–
reduction in metallic Fe and Mn nanoparticles to Fe 2O3and
Mn 2O3, respectively: 6Li 2O + 2Mn + 2Fe MMn 2O3+F e 2O3+ 12-
Li + 12e/C0. But the initial charge–discharge of the MnFe 2O4-2-600
showed three voltage plateaus at ca. 0.62, 0.72, and 0.86 V, corre-
sponding to the reduction in Fe3+to Fe and Mn3+to Mn during
the initial discharge process. Meanwhile, three defined plateaus
are observed in the charging process at ca. 1.51, 2.25, and 2.58 V,
corresponding to the oxidation of Fe to Fe3+and Mn to Mn3+.
Fig. 7 b shows the discharge capacity as a function of cycle num-
ber at current densities of 0.2 and 0.8 C in the voltage range of
0.01–3.0 V versus Li/Li+for MnFe 2O4-2, MnFe 2O4-2-400, and
MnFe 2O4-2-600, respectively. From the second cycle onwards,
the discharge capacity only decreases slightly for mesoporous
MnFe 2O4microspheres. After 50 cycles at 0.2 C, a high discharge
capacity of 678.6 mA h g/C01is still retained for MnFe 2O4-2, corre-
sponding to 81.1% of the second discharge capacity, which is higher
than porous CoMn 2O4of 624 mA g/C01[17]. Even at a high current
density of 0.8 C, a discharge capacity of 442.0 mA h g/C01is retained
after 50 cycles. The average capacity fading rate is around 0.47 and
0.77%/cycle at 0.2 and 0.8 C, respectively. After 50 cycles at 0.2 C, a
higher discharge capacity of 712.2 mA h g/C01is still retained for
MnFe 2O4-2-400, corresponding to 85.3% of the second discharge
capacity. At a high current density of 0.8 C, a discharge capacity
of 552.2 mA h g/C01is retained after 50 cycles. The average capacity
fading rate is around 0.28 and 0.48%/cycle at 0.2 and 0.8 C, respec-
tively. Compared with the electrochemical performance of MnFe 2-
O4-2, MnFe 2O4-2-400 after the decomposition of carbon800 600 400 200 0
Fe 2p1/2Fe 2p3/2Intensity (a.u.)
Binding Energy (eV)
C1sO 1sMn 2p1/2Mn 2p3/2
660 655 650 645 640 635 630Mn 2p3/2
Mn 2p1/2
653.0 eVIntensity (a.u.)
Binding Energy (eV)641.5 eV
745 740 735 730 725 720 715 710 705 Intensity (a.u.)
Binding Energy (eV)Fe 2p3/2 Fe 2p1/2
724.9 eV711.5 eV
538 536 534 532 530 528 526533.3 eV531.6 eVIntensity (a.u.)
Binding Energy (eV)O 1s
530.1 eV(d) (c) (b) (a)
Fig. 4. XPS spectra of MnFe 2O4-2 microspheres: (a) wide spectrum, (b) Mn 2p, (c) Fe 2p, and (d) O 1s.
Fig. 5. Formation illustration of mesoporous MnFe 2O4microspheres.Z. Zhang et al. / Journal of Colloid and Interface Science 398 (2013) 185–192 189

200 400 600 8009092949698100
2.08 %
Temperature (oC) TG Weight (wt%)8.62 %1.16%
20 30 40 50 60 70 8 0MnFe2O4-2
MnFe2O4-2-600MnFe2O4-2-400Intensity (a.u.)
2Theta (Degree)(440)
(511)(400)(311)
(220)
**
+
++++
++
++ *Mn2O3
+Fe2O3(b) (a)
(c) (d)
(e) (f)
200 400 600 800 200 400 600 800 MnFe2O4-2
MnFe2O4-2-400
MnFe2O4-2-600 MnFe2O4-2
MnFe2O4-2-400
MnFe2O4-2-600H2-TPR Signal
Temperature (oC) Temperature (oC)O2 -TPO Signal(h) (g)
Fig. 6. TG curve of the MnFe 2O4-2 (a), XRD patterns of MnFe 2O4-2, MnFe 2O4-2-400 and MnFe 2O4-2-600 (b), SEM images of MnFe 2O4-2-400 (c) and of MnFe 2O4-2-600 (d), TEM
images of MnFe 2O4-2-400, (e) and MnFe 2O4-2-600 (f), H 2-TPR (g) and O 2-TPO (h) curves of MnFe 2O4-2, MnFe 2O4-2-400 and MnFe 2O4-2-600.190 Z. Zhang et al. / Journal of Colloid and Interface Science 398 (2013) 185–192

contamination showed better electrochemical performance. The
discharge capacity decreases quickly for MnFe 2O4-2-600 (the mix-
ture of Fe 2O3and Mn 2O3). After 50 cycles at 0.2 C, a low discharge
capacity of 410.3 mA h g/C01is retained, corresponding to 61.3% of
the second discharge capacity. When a high current density of
0.8 C is used, a discharge capacity of only 162.2 mA h g/C01is re-
tained after 50 cycles. The average capacity fading rate is around
0.78 and 1.32%/cycle at 0.2 and 0.8 C, respectively. The superior
electrochemical performance of mesoporous MnFe 2O4-2-400
microspheres can be attributed to the following four factors: (1)
the nanometer-sized subunits make the conversion reaction more
feasible, which contributes to the high specific capacity [43–45] ;
(2) nanocrystalline metal oxides with proper calcination tempera-
ture should increase crystallinity of nanosized grains, thus result-
ing in good cyclic stability [46,47] ; (3) the porosity structure can
buffer the large volume change of anodes based on the conversion
reaction during the repeated Li+insertion/extraction, thus alleviat-
ing the pulverization problem and enhancing the cycling perfor-
mance [48,49] , and can be advantageous for lithium-storage
applications that require rapid ion transport and a high contact
area between the electrode and the electrolyte [50]; and (4) the
decomposition of carbon species such as HOCH 2CH2OH and
CH3COOC 2H5adsorbed on the surface of mesoporous MnFe 2O4
microspheres may improve the cyclic stability.
However, our prepared mesoporous MnFe 2O4microspheres did
not show excellent cycling property. The recent work proved that
the incorporation of carbon materials with metal oxides, such as
carbon-coated Fe 2O3hollow nanohorns on the CNT backbone
[51],F e 2O3@C nanoparticles [52], nanocrystal manganese oxide
(Mn 3O4, MnO) anchored on graphite nanosheets [53], and amor-
phous CoSnO 3@C nanoboxes [54], can improve their electrochem-
ical cycling property. Therefore, the combination carbon materials
with MnFe 2O4may further enhance the electrochemical property
of MnFe 2O4.
4. Conclusions
In summary, we have synthesized mesoporous manganese fer-
rite (MnFe 2O4) microspheres composed of nanoparticles (10–
30 nm). These microspheres are in the range of 100–300 nm in size
and have a surface area of 60.2–86.8 m2g/C01, which can be tuned by
varying the CH 3COOK amounts added. After calcination at 600 /C176C,
MnFe 2O4is decomposed to Mn 2O3and Fe 2O3. The mesoporous
MnFe 2O4microspheres calcined at 400 /C176C show the best electro-
chemical performance than those of the samples without calcina-
tion and calcined at 600 /C176C. The work will be helpful to thefabrication and development of nanostructured anode materials
with high capacity and long cycling life for Li-ion batteries.
Acknowledgments
The authors gratefully acknowledge the supports from the Hun-
dred Talents Program of the Chinese Academy of Sciences (CAS),
State Key Laboratory of Multiphase Complex Systems of China
(No. MPCS-2011-D-14), and National Natural Science Foundation
of China (Nos. 21031005 and 51272252).
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