Supplemental Material
Hierarchical
mesoporous/microporus
carbon
with
graphitized
frameworks for high-performance lithium-ion batteries
Yingying Lv,a Zhangxiong Wu,b Yin Fang,a Xufang Qian,a Abdullah M. Asiri,c Bo Tua
and Dongyuan Zhao*, a, b
a
Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and
Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai
200433, P. R. China.
b
Department of Chemical Engineering, Moansh University, Clayton, VIC 3800,
Australia.
c
Chemistry Department and The Center of Excellence for Advanced Materials
Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
Tel: +86-21-5163-0205; Fax: +86-21-5163-0307
E-mail: dyzhao@fudan.edu.cn
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1.Experimental section
1.1 Chemicals
The mesoporous zeolite Y templates were purchased from Novel Chemical
Technology Co, Ltd (Shanghai, China). High-purity methane (99.99 %) gas was
purchased from Sinopharm Chemical Reagent Co., Ltd. Hydrofluoric (HF) acid (40 %)
and hydrochloric acid (HCl) were purchased from Shanghai Chemical Company. All
the chemicals were used as received without further purification. Deionized water was
used wherever needed.
1.2 Synthesis
The hierarchical meso/micro-porous carbons were prepared as follows: an
alumina boat loaded with 0.5 g of the zeolites was placed in a flow-through tube
furnace. The furnace was heated to 600 °C (5 °C/min) under argon flow (60 mL/min).
Then, the gas supply was switched from argon to methane (60 mL/min) which was
introduced into the reactor at 600 °C. The temperature was further increased to the
target temperature (700, 800, or 900 °C) and held for 1-4 h for carbon deposition,
growth and graphitization, and then cooled to room temperature under inert argon gas.
The resultant zeolite/carbon (denoted as ZY-x-y, where x stands for the CVD
temperature and y for the duration time) composites were washed with 20 % HF for
several times, followed by refluxing at 60 °C in concentrated HCl for 3 h to
completely remove the zeolite templates. After washed with copious amount of water,
the resultant carbon materials were dried in an oven at 100 °C. At this stage,
thermogravimetric analysis indicated a residual mass typically lower than 2 %, which
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confirmed that the carbon materials were virtually zeolite-free. The resultant carbon
samples were denoted as CY-x-y, where CY stands for the meso/micro-porous carbons
replicated from mesoporous zeolite Y, x for the CVD temperature, and y for the
duration time.
1.3 Characterization
Powder X-ray diffraction (XRD) patterns were acquired by using a D8
equipment from Bruker Instruments (wavelength  of 0.154 nm, Cu Kα radiation).
Raman spectra were obtained with a Dilor LabRam-1B Raman spectroscope, using
the He–Ne laser with the excitation wavelength of 514 nm. Thermogravimetric (TG)
analyses were conducted by using a Mettler Toledo TGA-SDTA851 analyzer
(Switzerland) from 30 to 900 °C under air (20 mL/min). Scanning electron
microscopy (SEM) images were obtained with a Hitach S4800 scanning electron
microscope (Japan) operated at 1 kV. Nitrogen sorption isotherms were measured on
a Micromeritics ASAP 2420 analyzer at 77 K. Before measurements, the samples
were outgassed at 200 °C in vacuum for 6 h. The Brumauer–Emmett–Teller (BET)
method was utilized to calculate the specific surface areas. The pore size distribution
was derived from the adsorption branches of the isotherms by using the NLDFT
(Nonlocal density functional theory) method, and the total pore volumes (Vt) were
estimated from the adsorbed amount at a relative pressure of 0.995. The micropore
volume and micropore surface area were calculated by using the V–t plot method.
Transmission electron microscopy (TEM) experiments were conducted on a JEOL
2100F microscope (Japan) operated at 200 kV. The samples for TEM measurements
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were ground and suspended in ethanol and then supported onto a lacey carbon film on
a copper grid for direct observation.
1.4 Electrochemical measurements
The electrodes were prepared by mixing 90 % of the nanoporous carbon with
10 % of polyvinylidene fluoride (PVDF) binder dispersed in N-methylpyrrolidinone
(NMP) solvent. Anode electrodes were produced by coating the slurry on copper foils
and followed by drying at 80 °C for 12 h. The resulting slurry-coated copper foil was
roll-pressed with a punching machine. The electrolyte solution was 1 M LiPF6 in
ethylene carbonate (EC)/dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC)
(1 : 1 : 1 by volume). Electrochemical performance tests were conducted on 2032
coin-type cells, which were fabricated in an argon-filled glove box using lithium
metal as the counter electrode and a microporous polyethylene separator. Lithium
insertion into a carbon electrode was referred to as discharge and extraction as charge.
The cell capacity was calculated on the basis of the weight of the carbon active
material.
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FIG. S1. SEM images of the hierarchical meso/micro-porous carbons synthesized via
a methane CVD process at 800 °C for 1 h (a), 4 h (b), 6 h (c), and 900 °C for 2 h (d),
respectively.
FIG. S2. Raman spectra of the hierarchical meso/micro-porous carbons synthesized
via a methane CVD process at 700 (a), 800 (b) and 900 °C (c) for 3 h, respectively.
The intensity ratio (ID/IG) of the two bands is about 0.90 (CY-700-3h, line a), 0.84
(CY-800-3h, line b) and 0.76 (CY-900-3h, line c), respectively, demonstrating the
improving graphitization degree as the increasing temperature.
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FIG. S3. The TEM image of the hierarchical meso/micro-porous carbons synthesized
via a methane CVD process at 900 °C for 3 h.
FIG. S4. N2 sorption isotherms (A) and the corresponding pore size distribution
curves (B) of the hierarchical meso/micro-porous carbons synthesized via a methane
CVD process at 700 - 900 °C for 3 h and 900 °C for 4 h, respectively.
TABLE S1. Textural properties of the hierarchical meso/micro-porous carbons.
Sample
SBET a
(m2/g)
VTotal b
(cm3/g)
SMic c
(m2/g)
VMic d
(cm3/g)
CY-700-3h
CY-800-3h
CY-900-3h
CY-900-4h
2218
2136
2177
1423
1.4
1.3
1.2
0.89
1595
1530
1825
1007
0.68
0.66
0.75
0.43
a Surface
b Total
areas were obtained by the BET method from adsorption branches of the isotherms.
pore volumes were estimated from the adsorbed amount at p/p0 = 0.995.
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c
Micropore surface areas and d micropore volumes were calculated through the t-plot method.
2. Zeolite/carbon composites
The zeolite/carbon composites prepared at CVD temperature of 700-800 °C and
a constant duration time of 3 h lose 6.0 wt % of its original weight up to 500 °C, and
is completely combusted at ~ 700 °C (Fig. S4), demonstrating excellent oxidation
resistance in air. For samples prepared at a higher temperature of 900 °C and a
duration time of 3 h, a weight loss of only 1.0 wt % at a temperature up to 500 °C and
completely combusted temperature at about 800 °C is demonstrated, suggesting
higher graphization degree. A higher carbon yield is obtained at a higher temperature,
which increases from 18 to 29 wt % as the temperature increases from 700 to 900 °C,
and then further to 37 % as the duration time is prolonged to 4 h at 900 °C.
Replication of zeolite-like structural regularity requires extensive infiltration of the
carbon precursor into the zeolite pores of templates, which is consistent with the XRD
results (Fig. 2).
Nitrogen sorption isotherms (Fig. S5A) of the zeolite/carbon composites
obtained at 800 °C for 1-3 h show typical type I curves and H2 hysteresis loops with
little change for the mesopore size. However, the surface areas and total pore volumes
decrease dramatically after the CVD treatment, demonstrating that the zeolite
micropores are filled by the deposited carbon gradually. The cumulative pore volume
(Fig. S5B) calculated from the adsorption branch suggests that the reduction of the
surface area and total pore volume is mainly attributed to the filling micropores (Table
S2). At a high temperature of 900 °C, the surface area and pore volume of the
zeolite/carbon composites further decrease significantly, suggesting almost a full
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filling of carbon in zeolite micropores.
FIG. S5. TG curves of the zeolite/carbon composites prepared via a methane CVD
process at 700 °C (a), 800 °C (b), 900 °C (c) for 3 h and 900 °C for 4 h (d),
respectively.
FIG. S6. N2 sorption isotherms (left) and accumulative pore volume distribution (right)
of the zeolite templates and the zeolite/carbon composite samples prepared via a
methane CVD process at 800 °C for 1-3 h, and 900 °C for 2 h.
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TABLE S2. Textural properties of the mesoporous zeolite template and zeolite/carbon
composites.
Sample
Zeolite Ya
a
SBET c
(m2/g)
VTotal d
(cm3/g)
SMic e
(m2/g)
VMicf
(cm3/g)
VMeso g
(cm3/g)
743
0.40
678
0.26
0.14
ZY-800-1h
b
444
0.30
387
0.15
0.15
ZY-800-2h
ZY-800-3h
ZY-900-3h
172
31
15
0.16
0.08
0.05
136
6
-
0.06
0.003
-
0.10
0.077
-
Mesoporous zeolite Y was used as a template, through a methane CVD method at a temperature
of 800 °C for 1 h; b a zeolite/carbon composites named as ZY-800-1h was obtained. Following, a
series of zeolite/carbon composites obtained at 800-900 °C for 1-3 h was synthesized by this
method. c Surface areas were obtained by the BET method from adsorption branches of the
isotherms. d Total pore volumes were estimated from the adsorbed amount at p/p0 = 0.995. e
Micropore surface areas and f micropore volumes were calculated through the t-plot method. g
Mesopore volumes were calculated as that VMeso = VTotal – VMic.
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