Preparation and characterization of electrospun.pdf

Preparation and characterization of electrospunLiFePO4/carbon complex improving rate performanceat high C-rate

Sei-Hyun Lee • Min-Jung Jung • Ji Sun Im •

Kyou-Yoon Sheem • Young-Seak Lee

Received: 15 December 2009 / Accepted: 6 February 2010 / Published online: 18 September 2010

� Springer Science+Business Media B.V. 2010

Abstract LiFePO4/carbon complexes were prepared by electrospinning to

improve rate performance at high C-rate and their electrochemical properties were

investigated to be used as a cathode active material for lithium ion battery. The

LiFePO4/carbon complexes were prepared by the electrospinning method. The

prepared samples were characterized by SEM, EDS, XRD, TGA, electrometer, and

electrochemical analysis. The LiFePO4/carbon complexes prepared have a contin-

uous structure with carbon-coated LiFePO4 and the LiFePO4 in LiFePO4/carbon

complex has improved thermal stability from carbon coating. The conductivity of

LiFePO4/carbon complex heat-treated at 800 �C is measured as 2.23 9 10-2 S

cm-1, which is about 106–107 times more than that of raw LiFePO4. The capacity

ratio of coin cell manufactured from raw LiFePO4 is 40%, whereas the capacity

ratio of coin cell manufactured from LiFePO4/carbon complex heat-treated at

800 �C is 61% (10 C/0.1 C). The improved rate performance of LiFePO4/carbon

complex heat-treated at 800 �C is due to the carbon coating and good electrical

connection.

Keywords High C-rate � Rate performance � LiFePO4/carbon complex �Electrospinning

S.-H. Lee

Department of Electrical and Electronic Engineering, Korea Polytechnic College,

Daejeon 300-702, Republic of Korea

M.-J. Jung � J. S. Im � Y.-S. Lee (&)

Department of Applied Chemistry and Biological Engineering, Chungnam National University,

Daejeon 305-764, Republic of Korea

e-mail: [email protected]

K.-Y. Sheem

Energy Lab., CRD Center, Samsung SDI, Suwon, Gyeonggi-do 443-390, Republic of Korea

123

Res Chem Intermed (2010) 36:591–602

DOI 10.1007/s11164-010-0167-9

Introduction

Recently, lithium-ion batteries have drawn an interest to be used for electric vehicles

(EVs), hybrid electric vehicles (HEVs), dispersed energy storage systems, etc. [1].

Such applications require safety, high-rate performance, and energy density [2].

Especially good rate performance at high C-rate is essential for batteries of electric

vehicles [3]. Lithium-ion batteries consist of a cathode, an anode, and an electrolyte.

Among several components of the lithium-ion batteries, cathode materials are a

major concern for the improvement of rate performance at high C-rate. Cobalt or

manganese-based oxides, such as LiCoO2 and Li2MnO4, are generally used as

cathode materials of commercial lithium-ion batteries. The cobalt-based oxides have

disadvantages of high cost and toxicity [4], whereas manganese-based oxides have

advantages of low cost and low toxicity. However, they suffer from important

capacity fading during cycling, especially at high temperatures [5]. Since the study of

Padhi et al. [6], the olivine structure of lithium iron phosphate (LFP, LiFePO4) has

attracted great interest as a substitute for conventional cathode materials.

It has many advantages of high energy density, high theoretic capacity, low cost,

safety, and environmental friendliness [7]. However, LiFePO4 has poor conductiv-

ity. This disadvantage results from the low lithium-ion diffusion rate and low

electronic conductivity in the LiFePO4 phase. In order to improve the electronic

conductivity of LiFePO4, some methods have been studied, including coating

conductive carbon [8–10] or metals [11–13] on LiFePO4 surface or doping ions in

the crystalline lattice of LiFePO4 [14–16]. Above all, the carbon-coating method is

very efficient in increasing conductivity of LiFePO4 due to high electronic

conductivity of carbon, and the increase of the electronic conductivity of LiFePO4

surface is expected to provide a good rate performance at high C-rate [17–19].

The LiFePO4/carbon complex has been prepared by the sol–gel method,

hydrothermal method, freeze–drying method, spray-pyrolysis method, etc. [20–24].

For improvement of the rate performance at high C-rate, LiFePO4 and carbon must

be connected effectively. Therefore, the ameliorated method is necessary to

manufacture a well-connected LiFePO4/carbon complex. Electrospinning is well

known as a simple and effective method for fabrication of complex [25, 26]. It is

expected that LiFePO4/carbon complex is manufactured well-connected form of

carbon and LiFePO4.

In this study, LiFePO4/carbon complexes for a cathode active material of a lithium-ion

battery were prepared by the electrospinning method in order to improve rate perfor-

mance at high C-rate, and their electrochemical characteristics were also evaluated.

Materials and methods

Preparation of LiFePO4/carbon complexes by electrospinning method

Carbon precursor, PAN (polyacrylonitrile, mW 80,000, Aldrich, USA) was

dissolved in DMF (N,N-dimethyl formamide, Acros, USA) at 80 �C, and its

concentration was 10 wt%.

592 S.-H. Lee et al.

123

An active material of cathode, LiFePO4 (lithium iron phosphate (LFP), Postech,

Korea) was added to PAN solution to produce a mixture solution with a

PAN:LiFePO4 ratio of 1:4, and then the solution was spun out of fibers with the

electrospinning experiment. The electrospinning conditions were as followings;

3 ml/h of solution feeding rate and 15 kV of applied electric power. The details of

the electrospinning method have been presented elsewhere [27]. After electrospin-

ning, as-spun fibers were stabilized at a temperature of 250 �C for 5 h in air with a

heating rate of 1 �C/min. The stabilized fibers were then heated at 600 and 800 �C

for 1 h in nitrogen atmosphere (heating rate: 10 �C/min) to investigate electro-

chemical property changes with different heat-treatment temperatures. The prepared

samples were named as follows; r-LFP (raw LiFePO4), LFP/C600 (LiFePO4/carbon

complex heat-treated at 600 �C), and LFP/C800 (LiFePO4/carbon complex heat-

treated at 800 �C).

Characterizations of LiFePO4/carbon complexes

The morphologies of the samples were observed with field emission scanning

electron microscope (SEM, S-5500, Hitachi, Japan). Elemental mapping was carried

out with energy dispersive spectroscopy (EDS) images. Crystal structures of

samples were investigated by X-ray diffraction (XRD, D/MAX-2200 Ultima/PC,

Rigaku International Corporation, Japan) with a Cu cathode (CuKa radiation

k = 1.54056 A) at room temperature. Carbon content was evaluated by the

thermogravimetric analysis (TGA, 2960SDT, TA Instruments, USA) in air and

nitrogen from room temperature to 600 �C with a heating rate of 5 �C min-1. The

conductivity of LiFePO4/carbon complexes was measured in air at ambient

temperature with an electrometer (6514 system electrometer, Keithley, USA).

Electrochemical analysis of LiFePO4/carbon complex

LiFePO4/carbon complex electrodes were fabricated by mixing the prepared

electrospun LiFePO4/carbon complex (80 wt%) and polyvinylidene fluoride (PVDF,

Aldrich) binder (20 wt%). LiFePO4 electrode was fabricated by mixing r-LFP (70

wt%), PVDF (20 wt%), and carbon black (10 wt%, Super-P, MMM Carbon) as a

conductive material. The disc electrodes, having a diameter of 16 mm, were cut out

of the coating film and cast onto metal foil current collector using a punch. The coin

half cells (CR2016 standard size) were assembled in an argon-filled glove box at

room temperature. The electrolyte was prepared by mixing ethylene carbonate (EC,

Aldrich), ethyl methyl carbonate (EMC, Aldrich), and dimethyl carbonate (DMC,

Aldrich) with a ratio of EC:EMC:DMC = 3:3:4 to assemble the coin cells.

Electrochemical investigations were performed by using a CC/CV mode. The coin

cells were named as follows; C-rLFP (coin cell manufactured from r-LFP), C-

LC600 (coin cell manufactured from LFP/C600), and C-LC800 (coin cell

manufactured from LFP/C800). The ratio of coin cells with each sample are

presented in Table 1.

Preparation and characterization of electrospun LiFePO4/carbon complex 593

123

Results and discussion

Morphology of electrospun LiFePO4/carbon complexes

Figure 1 shows SEM images of r-LFP and LiFePO4/carbon complex samples

prepared with different heat-treatment temperatures. As shown in Fig. 1a, r-LFP is

observed with uniform oval-shaped particles. It confirms many clusters of small

particles that have an average particle size with a major axis of about 200 nm.

Manufactured LFP/C600 and LFP/C800 by electrospinning (Fig. 1b, c) are fibrous

with a rough surface. The average diameter of LiFePO4/carbon complexes is about

5 ± 0.8 lm. The surfaces of the LiFePO4/carbon complexes become rougher with

increasing heat-treatment temperature. The surface of LFP/C800 is more porous

than that of LFP/C600 because the PAN shrank during heat-treatment [28]. Since

PAN shrinks more at higher heat-treatment temperature [29], LFP/C800 is more

Table 1 The ratio of coin cells with each sample

The ratio of coin cell (wt%) Real weight of

LiFePO4 in cell (g)LiFePO4 Conducting material Binder

CB PBCa

C-rLFP 70.0 10.0 – 20.0 0.0060

C-LC600 71.1 – 8.9 20.0 0.0037

C-LC800 72.2 – 7.8 20.0 0.0047

a PAN-based carbon

Fig. 1 SEM images of a r-LFP, b LFP/C600, c LFP/C800, d a cross-section of LFP/C600 and e a cross-section of LFP/C800


123

porous than LFP/C600. It is expected to have more chances for electrolyte to be

absorbed into an internal electrode, improving rate performance.

The schematic diagrams of r-LFP, prepared LiFePO4/carbon complex, and

electron transfer pathway of the prepared complex in this study is suggested in

Fig. 2. r-LFP is observed as a form of clusters, without any connection between

each LiFePO4 particle. However, LiFePO4/carbon complexes are observed as a

continuous structure with LiFePO4 particles coated and linked with PAN-based

carbon. As shown in the cross section of LiFePO4/carbon complexes (Fig. 1d, e), it

is also observed that LiFePO4 particles are dispersed uniformly in LiFePO4/carbon

complex and coated and connected with carbon. In addition, LiFePO4/carbon

complexes have a high-density fiber structure due to the effect of the electrospinning

method. As shown in Fig. 2b, these carbon coatings and connections ensure that

LiFePO4 particles get electrons effectively, and could further alleviate this

polarization phenomenon [30]. In the EDS images (Fig. 3), carbon is observed as

white spots on the surface of LiFePO4/carbon complexes. This can be another

evidence for the existence of carbon coating on the LiFePO4/carbon complex

surface.

XRD analysis

Figure 4 shows the XRD patterns of r-LFP and LiFePO4/carbon complexes. The

XRD pattern of r-LFP (Fig. 4a) is identified as an orthorhombic system in Pnmaspace group (JCPDS card No. 81-1137) and it is almost similar to those of LiFePO4/

carbon complexes (Fig. 4b,c), not showing the presence of crystalline carbon. It is

hard to observe the crystalline carbon peak (002) in the XRD patterns of the

complexes due to the overlapping of the crystalline carbon peak with LiFePO4 peak

(111).

According to previous studies [31], XRD pattern of LiFePO4/carbon complex

treated at 800 �C exhibited the impurity peaks caused by reduction of LiFePO4,

such as Fe2P (22, 23�) or Li3PO4 (41, 44�). The presence of impurities causes the

decrease of ionic conductivity, capacity, and cycling rates [32–34]. In this study,

structural changes of LiFePO4 are not observed in the XRD patterns of the LiFePO4/

carbon complexes (Fig. 1b, c). This result suggests that carbon coating contributes

to increasing thermal stability of LiFePO4. It is expected that electrochemical

properties of LiFePO4 in LiFePO4/carbon complexes are not affected by impurities.

Fig. 2 The schematic diagrams of a r-LFP, b prepared LiFePO4/carbon complex, and c electron transferpathway of the LiFePO4/carbon complex


123

Fig. 3 EDS images of a LFP/C600, b LFP/C800, c C mapping of LFP/C600, and d C mapping of LFP/C800

20 30 40 50 60 70

313

213

701

040

430

331

412,

610

231

131

022

102,

221

321,

212

112

41012

131

1

301

020

111

01121

010

1

LiFePO4(c)

(b)

Inte

nsity

(a.

u.)

2θ (Degree)

(a)

200

Fig. 4 X-ray diffraction patterns of (a) r-LFP, (b) LFP/C600, and (c) LFP/C800


123

TGA and electrical conductivity analysis

Figure 5 shows TGA curves of r-LFP, LiFePO4/carbon complexes, and PAN-based

electrospun carbon fiber under air flow, and stabilized electrospun PAN fiber under

N2 flow. As shown in the TGA curve of r-LFP (Fig. 5a), it is observed that oxidation

of r-LFP started at around 250 �C. As it has been previously reported by Belharouak

[35], r-LFP is oxidized with two steps of weight increment and formatted two

phases, Li3Fe2(PO4)3 and Fe2O3. In addition, the TGA curve shows a weight gain of

2.2% for the r-LFP after oxidation. As shown in Fig. 4b and c, LiFePO4 in LiFePO4/

carbon complexes is also oxidized at or above 400 �C. The LiFePO4 oxidation peak

of LFP/C600 and LFP/C800 is shifted to a higher temperature than that of r-LFP,

which means that the carbon coating will be able to delay oxidation of LiFePO4 and

0

20

40

60

80

100(a)

(1)

(2)

(3)

(4)

(5)

Res

idua

l mas

s (%

)

Temperature (Co)

(b)

100 200 300 400 500 600 700 800

100 200 300 400 500 600

85

90

95

100

105(b)

(1)

(2)

(3)

Temperature (Co)

Res

idua

l mas

s (%

)

Fig. 5 TGA results of prepared samples (a) and expansion of selected area (b); (1) r-LFP observed in air,(2) LFP/C600 observed in air, (3) LFP/C800 observed in air, (4) PAN-based electrospun carbon fiberobserved in air, and (5) stabilized electrospun PAN fiber in observed nitrogen


123

improve thermal stability. The improved thermal stability of active material is a

very important factor to determine the safety of Li-ion batteries. This result is

similar to XRD patterns of the LiFePO4/carbon complexes, where no structural

changes of LiFePO4 were observed.

Below 400 �C, the weight loss of LFP/C800 is faster than that of LFP/C600

because LFP/C800 is more porous than LFP/C600, as explained above. Rapid

weight loss of LFP/C600 and LFP/C800 is observed at around 400 and 450 �C,

respectively. The starting temperature of rapid weight loss of LiFePO4/carbon

complexes increases with increasing heat-treatment temperature. Weight loss of

LiFePO4/carbon complexes occurs because of decomposition of existing carbon in

LiFePO4/carbon complexes. It is also observed in TGA curve of PAN-based

electrospun carbon fiber (Fig. 5d). A weight loss of LiFePO4/carbon complexes is

associated with oxidation of carbon and some organic compounds, which means that

carbon contents of the LiFePO4/C complex can be calculated from weight loss of

the complex and the amount of carbon coated on the LFP/C600 and LFP/C800 is

calculated to be around 11.1 and 9.8 wt%, respectively. The carbon amount of

LiFePO4/carbon complexes is calculated theoretically using TGA curve of

stabilized electrospun PAN fiber. According to the TGA curve of stabilized

electrospun PAN fiber (Fig 5e), the carbon yield of PAN in LFP/C600 and LFP/

C800 is estimated to be around 43.5 and 34.7 wt%, respectively. The theoretical

amount of carbon coated on the LFP/C600 and LFP/C800 is calculated to be around

9.8 and 7.9 wt%, respectively.

Even though LFP/C600 contains a larger percentage of carbon than LFP/C800,

crystallinity of carbon in LFP/C800 would be higher than that of carbon in LFP/

C600 because crystallinity and conductivity of carbon increases with increasing

heat-treatment temperature [36]. Therefore, it is expected that conductivity of LFP/

C800 has higher than that of LFP/C600. Actually, the conductivity of LFP/C600 and

LFP/C800 is measured at 5.62 9 10-4 and 2.23 9 10-2 S cm-1, respectively. LFP/

C800 has improved conductivity about 40 times more than LFP/C600. Therefore, it

suggests that increasing the heat-treatment temperature in this experiment led to an

increase in the conductivity. Compared to low electrical conductivity of LiFePO4

about 10-9–10-10 S cm-1 [37], conductivity of LFP/C800 is considerably increased

about 107–108 times. As each LiFePO4 particle is coated with carbon, a conductive

network is formed between the LiFePO4 particles. Therefore, conductivity of the

material can dramatically increase. It is expected to improve rate performance at a

high C-rate.

Electrochemical performance

Figures 6, 7, 8, and 9 and Table 2 show the discharge profiles of the coin cells

measured from 4.5 and 2.0 V vs. Li at different discharge rates of 0.1, 1, 5, and

10 C. The cells are cycled between 2.4 and 4.1 V. In case of C-LC600, it shows a

poor electrochemical property with the discharge capacities of 0.08 mAh g-1 at 0.1

C, which is much lower than the discharge capacities of C-rLFP, 153.18 mAh g-1 at

0.1 C. This is the conductivity difference between conductive materials used for cell

manufacturing. C-rLFP was manufactured with carbon black as a conductive


123

material, which usually has a conductivity of 10-1–102 S cm-1 [38], whereas

C-LC600 was manufactured with heat-treated PAN fibers at 600 �C, which has a

measured conductivity of 3.34 9 10-3 S cm-1. Therefore, due to the low

conductivity of heat-treated PAN fiber at 600 �C, the conductivity of C-LC600 is

2.4

2.8

3.2

3.6

4.0

Vol

tage

(V

vs.

Li/L

i+)

Capacity (mAh g-1)

C-rLFP C-LC600 C-LC800

0 20 40 60 80 100 120 140 160

Fig. 6 The discharge curvesat 0.1 C

0 20 40 60 80 100 120 140 160

2.4

2.8

3.2

3.6

4.0

Vol

tage

(V

vs.

Li/L

i+)

Capacity (mAh g-1)


Fig. 7 The discharge curvesat 1 C

2.4

2.8

3.2

3.6

4.0

Vol

tage

(V

vs.

Li/L

i+)

Capacity (mAh g-1)


0 20 40 60 80 100 120



123

expected to be significantly lower than that of C-rLFP, causing low discharge

capacity of C-LC600. The low conductivity of heat-treated PAN fiber at 600 �C is

due to the presence of a large amount of amorphous carbon in the fiber heat-treated

at relatively low temperature and the amorphous carbon obstructs movement of

lithium ion inside of the active materials.

The discharge capacities of C-rLFP are 153.18 mAh g-1 (0.1 C) and 61.06 mAh

g-1 (10 C), and the capacity ratio of 10 C/0.1 C is 40%. In case of C-LC800,

discharge capacities are 139.95 mAh g-1 (0.1 C) and 85.60 mAh g-1 (10 C), and

the capacity ratio of 10 C/0.1 C is 61%. The high rate performance reveals that the

LiFePO4/carbon complex would be suited for cathode material of a high-power

lithium-ion battery. The high rate performance in the high discharge rate condition

is attributed to dramatic conductivity improvement through carbon coating and

connecting.

At a high discharge rate, the lithium ion diffusion is restricted inside of active

materials [5]. For this reason, discharge capacity and rate performance of cell is

greatly influenced by surface conductivity of active materials and connection of

active materials at high discharge rate. There are continuities between restricting of

lithium-ion diffusion and change of the voltage plateau region [5]. As Figs. 6, 7, 8,

and 9 show, the voltage plateau of C-rLFP is changed dramatically with increasing

discharge rate. However, the C-LC800 has an excellent flat voltage plateau around

3.2–3.4 V in most discharge rates. This effect can be attributed to the improved

lithium-ion diffusion at active material surface, due to the carbon coating and

connecting.

0 20 40 60 80 100

2.4

2.8

3.2

3.6

4.0 C-rLFP C-LC600 C-LC800

Vol

tage

(V

vs.

Li/L

i+ )Capacity (mAh g-1)


Table 2 Discharge capacity

with different discharge rateDischarge capacity (mAh g-1)

0.1 C 1 C 5 C 10 C

C-rLFP 153.18 146.23 105.12 61.06

C-LC600 0.08 0.04 0.03 0.03

C-LC800 139.95 112.23 93.52 85.60


123

Conclusions

Electrospun LiFePO4/carbon complexes are manufactured as high dense fibers with

continuous structure of LiFePO4 particles which are linked with PAN-based carbon

coating. In this study, structural changes of LiFePO4 are not observed in the XRD

patterns of LiFePO4/carbon complexes. As shown in the TGA curves, the LiFePO4

oxidation peak of LiFePO4/carbon complexes are shifted to higher temperatures

than that of r-LFP. These results suggest that carbon coating contributes to

increasing thermal stability of LiFePO4. The amount of carbon coated on the LFP/

C600 and LFP/C800 is calculated to be around 11.1–9.8 wt%, respectively, from

TGA curves. The conductivity of LFP/C600 and LFP/C800 is measured to be

5.62 9 10-4 and 2.23 9 10-2 S cm-1, respectively. Even though LFP/C600 con-

tains a larger percentage of carbon than LFP/C800, crystallinity of carbon in LFP/

C800 would be higher than that of carbon in LFP/C600 because of crystallinity and

conductivity of carbon increase with increasing heat-treatment temperature.

Therefore, conductivity of LFP/C800 is higher than that of LFP/C600. The discharge

capacities of C-rLFP are 153.18 mAh g-1 (0.1 C) and 61.06 mAh g-1 (10 C), and

the capacity ratio of 10 C/0.1 C is 40%. In case of C-LC800, discharge capacities

are 139.95 mAh g-1 (0.1 C) and 85.60 mAh g-1 (10 C), and the capacity ratio of 10

C/0.1 C is 61%. The improved rate performance of C-LC800 can be explained with

increased conductivity of active materials and network between active materials

caused by carbon coating and connecting.

Acknowledgments This work was partially supported by Samsung SDI, Korea.

References

1. D.Y. Park, D.Y. Park, Y. Lan, Y.S. Lim, M.S. Kim, J. Ind. Eng. Chem. 15, 588 (2009)

2. B.B. Owens, S. Passerini, W.H. Smyrl, Electrochim. Acta 45, 215 (1999)

3. J.K. Kim, News. Inf. Chem. Eng. 23, 423 (2005)

4. K. Wang, R. Cai, T. Yuan, X. Yu, R. Ran, Z. Shao, Electrochim. Acta 54, 2861 (2009)

5. Y.Z. Dong, Y.M. Zhao, Y.H. Chen, Z.F. He, Q. Kuang, Mater. Chem. Phys. 115, 245 (2009)

6. A.K. Padhi, K.S. Nanjudaswamy, J.B. Goodenough, J. Electrochem. Soc. 144, 1188 (1997)

7. M. Konarova, I. Taniguchi, Powder Technol. 191, 111 (2009)

8. Z. Chen, J.R. Dahn, J. Electrochem. Soc. 149, A1184 (2002)

9. H. Huang, S.C. Yin, L.F. Nazar, Electrochem. Solid State Lett. 4, A170 (2001)

10. C.H. Mi, X.B. Zhao, G.S. Cao, J.P. Tu, J. Electrochem. Soc. 152, A483 (2005)

11. W. Wang, J. Zhang, F. Chen, M. Anpo, D. He, Res. Chem. Intermed. 36, 163 (2010)

12. J.F. Ni, H.H. Zhou, J.T. Chen, X.X. Zhang, Mater. Lett. 59, 2361 (2005)

13. M. Abbate, S.M. Lala, L.A. Montoro, J.M. Rosolen, Electrochem. Solid State Lett. 8, A288 (2005)

14. H. Liu, Q. Cao, L.J. Fu, C. Li, Y.P. Wu, H.Q. Wu, Electrochem. Commun. 8, 1553 (2006)

15. G. Wang, Y. Cheng, M. Yan, Z. Jiang, J. Solid State Electrochem. 11, 457 (2007)

16. C.H. Mi, Y.X. Cao, X.G. Zhang, X.B. Zhao, H.L. Li, Powder Technol. 179, 171 (2007)

17. Y. Huang, K. Park, J.B. Goodenough, J. Electrochem. Soc. 153, A2282 (2006)

18. M.M. Doeff, J.D. Wilcox, R. Kostecki, G. Lau, J. Power Sources 163, 180 (2006)

19. X. Li, F. Kang, X. Bai, W. Shen, J. Electrochem. Commun. 9, 663 (2007)

20. K. Konstantinova, S. Bewlay, G.X. Wang, M. Lindsay, J.Z. Wang, H.K. Liu, S.X. Dou, J.-H. Ahn,

Electrochim. Acta 50, 421 (2004)

21. A. Kuwahara, S. Suzuki, M. Miyayama, The 48th Battery Symposium in Japan (2007), 2A05


123

22. H. Tannai, S. Koizumi, K. Dokko, H. Nakano and K. Kanamura, The 48th Battery Symposium in

Japan (2007), 2A09

23. V. Palomares, A. Goni, I.G. Muro, I. Meatza, M. Bengoechea, O. Miguel, T. Rojo, J. Power Sources

171, 879 (2007)

24. S.L. Bewlay, K. Konstantinov, G.X. Wang, S.X. Dou, H.K. Liu, Mater. Lett. 581, 788 (2004)

25. J.S. Im, O. Kwon, Y.H. Kim, S.J. Park, Y.S. Lee, Micropor. Mesopor. Mater. 115, 514 (2008)

26. J.S. Im, S.J. Kim, P.H. Kang, Y.S. Lee, J. Ind. Eng. Chem. 15, 699 (2009)

27. J.S. Im, J.S. Jang, Y.S. Lee, J. Ind. Eng. Chem. 15, 914 (2009)

28. E. Zussman, X. Chen, W. Ding, L. Calabri, D.A. Dikin, J.P. Quintana, R.S. Ruoff, Carbon 43, 2175

(2005)

29. J. Mittal, H. Konno, M. Inagaki, O.P. Bahl, Carbon 36, 1327 (1998)

30. Y. Wang, Y. Wang, E. Hosono, K. Wang, H. Zhou, Angew. Chem. Int. Ed. 47, 7461 (2008)

31. M. Konarova, I. Taniguchi, Mater. Res. Bull. 43, 3305 (2008)

32. A.A. Salah, A. Mauger, C.M. Julien, F. Gendron, Mater. Sci. Eng.129, 232 (2006)

33. C.M. Julien, A. Mauger, A. Ait-Salah, M. Massot, F. Gendron, K. Zaghib, Ionics 13, 395 (2007)

34. Z.L. Zhang, J.C. LU, Y.S. Yang, J. Inorg. Mater.22, 864 (2007)

35. I. Belharouak, C. Johnson, K. Amine, Electrochem. Commun. 7, 983 (2005)

36. S.H. Park, S.M. Jo, D.Y. Kim, W.S. Lee, B.C. Kim, Synth. Met. 150, 265 (2005)

37. H.C. Shin, W.I. Cho, H. Jang, Electrochim. Acta 52, 1472 (2006)

38. S. Wolff, in Carbon Black: Science and Technology, 2nd edn., ed. by J.B. Donnet, R.C. Bansal, M.J.

Wang (Marcel Dekker, New York, 1993), p. 271


123

Preparation and characterization of electrospun.pdf

Documents

Transcript of Preparation and characterization of electrospun.pdf