素子材料特論
第３授業

Li-ion電池負極（II）
ハードカーボン系負極

Anodic performance and their related factors
Performances

Capacity

Factors• Sites for Li incorporationand discharge• Reversibility of charge and discharge• Over potential• Non-electrochemical reaction

charge and discharge rate

• Diffusivity of Li

Non-dischargeable charge• Reactivity of electrolyte• Reactivity of anode, hetero atomic groups,
terminal C-H, edge carbon• Irreversible sites for Li incorporation

Cycle ability• Irreversible charge in structure

Safety• Stability of charged Li• Li-Carbon intercalation• Thermal stability of SEI• Reactivity of electrolyte

Potential for charge

Charge-Discharge Curves of Various Carbon Materials

1.8

Potential (V) vs. Li/Li

+

1.5
1.2
Graphitizable carbon

0.9
Non-graphitizable carbon

0.6Graphite

0.3
0.0
0

200

400

600

800

1000

-1

Capacity (mAh g )Figure 1-4. Charge-discharge profiles of representative carbon materials

Mechanisms for Lithium Insertion in Carbonaceous Materials

Figure 1-5. (a) Plot of reversible capacity for Li vs. HTT for a variety of carbon samples (□hard carbon, ■ soft carbon), (b) Charge capacity as a function of the height of stacking(Lc002)J. R. Dahn,* Tao Zheng, Yinghu Liu, J. S. Xue SCIENCE, 270, 27 OCTOBER 1995

Characteristics of various materials
Precursor

Graphite(over 2800oC)

Graphitizablecarbon(600~800oC)

Nongraphitizablecarbon(1000~1400oC)

Advantages

Disadvantages

Natural graphite
Artificial graphite
MCMB
Needle cokes
VGCF

Low dischargepotential(around 0.2V)
Long cycle life

Low discharge capacity(372 mAh/g)
High cost

MCMB
Meso phase pitch
Green cokes

High capacity(700~1000mAh/g)
Low cost

High discharge potential(around 1.0V)
High irreversible capacity
Poor cycle stability

Thermosetting polymer
Glassy carbon
Coal
Organic material
Stabilized isotropic pitch

High capacity(400~700mAh/g)
Low dischargepotential(around 0.1V)
Low cost

High irreversible capacity

Fig. 2. Plots of voltage versus reversible capacity for the second charge-discharge cycle of representative carbon
samples from regions 1, 2, and 3 of Fig. 1. (A) Synthetic graphite (Johnson-Matthey); (B) petroleum pitch (Crowley TarCo.) heated to 5500C; (C) resole resin (Occidental Chemical Co.) heated to 1 0000C. Arrows designate the directions
the curves are traversed as Li is added to (to the right) or removed from (to the left) the carbon samples.

Fig. 3. Reversible capacity of region 1 carbons plotted as a function of the probability P of turbostratic disorder
between adjacent carbon sheets. The line is the relation 0 = 372(1 - P), where Q is the capacity. For the purposes ofthis plot, samples corresponding to different symbols are equivalent.

ハードカーボンの製造•

原料：難黒鉛化性前駆体- Biomass: Husk, Cellulose, Sugar, Rignin, Tree, Crab（Chichin), …
- Polymer: Phenol Resin, Unsaturated Resin, Epoxy Resin- Pitch:Isotropic Pitch and Coke
• 熱処理温度- ８００～１４００℃• 構造- 難黒鉛化性カーボンハードカーボンの構造
Domain２次元的構造(a) Non-Graphitizing (Isotopic)

３次元的構造Cluster(b) Partially Graphitizing

Microdomain(c) Graphitizing

活性炭素繊維の微細構造
In order to remove oxygen containing functional groups for removing the heterogeneous effect of STM,
OG7A and OG20A were heat-treated at 800OC in a hydrogen atmosphere ( H2 / He =1/4).

OG20A-800H

OG7A-800H

Channeling
pore(Inter-particles)
Slit shaped pore(Intra-particle)

Slit shaped pore(Intra-particle)

5nm

25nm

5nm

25nm

Vacant spaces between the two domains of OG20A are larger than that of OG7A.
Domain size of OG20A is a little smaller than that of OG7A.
Slit type pores were observed in domains of OG7A and OG20A.
It can be presumed that almost pores larger than 2nm nucleated by the inter-particle
mechanism.
10ガラス炭素の微細構造

11

ハードカーボンの長所と短所•

長所- 高容量が可能- 安価（?）- 資源が豊富（?）- High rate property- Hybrid系材料が可能- 低温特性がよい。
- 電解液のPC使用可能
• 短所
- 低密度
- 放電プロフィルがNon-platten- 不純物の除去が困難- 低１st cycle Coulombic efficiency- 低Cycle性- …

Hard Carbon from Indonesian Mangrove Char
Elemental analysis & Surface area

STM image of IM1000

Elemental analysis (wt%)
C

H

N

O

Ash

S.A.
(m2/g)

IM

70.6

3.6

0.38

23.7

1.7

-

IM 700

89.4

1.0

0.72

582

3.1

318

IM 800

90.0

0.8

0.74

5.5

3.0

19

IM 900

91.0

0.6

1.17

4.3

3.0

3

IM 1000

91.5

0.5

1.13

4.0

2.9

54

1000

XRD
IM700
IM800
IM900
IM1000Intensity

800
600
400
200
0
10

20

30

40

50

2 theta14

Microstructure of carbon derived from mangrove charcoal and its application in Li-ion batteries, Liu, Tao; Luo, Ruiying; Qiao,
Wenming; Seong-Ho Yoon, et al., ELECTROCHIMICA ACTA, 55, 1696-1700, 2010

“Li+ storage sites in non-graphitizable carbons prepared from methylnaphthalene-derived isotropic pitches(MNIP)”, Carbon, 38, 995 1001 (2000), C. W. Park, S. I. Lee, S.H. Yoon, S. M. Oh

Li-NMR of Various Carbons
MAG(CCCV charge to 0V)

-100

-50

0

50

100

150
200
IMV1000(CCCV
charge 250
to 0V)

-100

-50

0

50

100

150

200

250

abundance

IMV2400(CCCV charge to 0V)
-100

-50

0

50

100

150

200

250

IMA1000(CCCV charge to 0V)
-100

-50

0

50

100

150

200

250

IMA700(CCCV charge to 0V)
-100

-50

0

50

100

ppm

150

200

250

ハードカーボンの充放電機構

Low-crystallized carbon materials for lithium-ion secondary batteries,
Hayato Higuchi, Keiichiro Uenae, Akira Kawakami
JOURNAL OF POWER SOURCES, 68, 1997

Hard Carbon from Indonesian Mangrove Char

Ch-Dis Profile
Potential (V) vs. Li/Li

+

2.0

1.5

1.0

0.5

Ar 1000
Vac 1000
0.0
0

100

200

300

400

500

600

Capacity (mAh/g)

Condition

Ch(mAh/g)Dis(mAh/g)Efficiency(1cy, %)

Cap.irrev.
(mAh/g)Ar 1000

628

469

74.7

159

Vac 1000

503

453

90.１

50

IM

IM V1000 showed the better initial efficiency than that of IM Ar1000
19理想的なハードカーボン
•
•
•
•
•
•
•
•
•
•
•

高密度： 1.9g/cm3以上
高容量： 650mAh/cc
高レート性： 90%以上（５C/0.2C: Half cell, ２０C/0.2C:Single cell）
Low Impurity: 100ppm以下
安価： 800円/Kg以下
高1st Coumbic efficiency
高低温特性
高サイクル性
豊富な原料からの調製
マイルドな炭化条件
Hybrid系が可能な材料：SnOxまたはSiとのハイブリッド化⇒高容量化⇒ 達成するためには、各々因子に対応する原因把握が要求。
⇒ まだ、原因解明が明らかになっていない。
⇒ 今後の研究に期待する。

Figure 1-15. Typical high performance materials as anode ;(a) Comparison of graphite, Si, Sn and Sb(b) Volume expansion model of Si during charge

High performance material & their problems
 SiO, Si and Sn (SiO 2100, Si 4200, Sn 931 mAh/g) are very promisingmaterials as anodic materials of LIB for their large theoretical capacities,
however, they have poor cycle performances because of internal crack inparticles caused by large volumetric expansion in charge process.
Li-Si systemRef.) J. Power Sources 192 (2) (2009) 644-651

CompoundStructure

Unit cell vol.
(A3)

Vol. / Si atom
(A3)

Si

Cubic

160.2

20.0

Li12Si7

Orthorhombic

243.6

58.0

Li14Si6

Rhombohedral

308.9

Li13Si4

Orthorhombic

538.4

Volume51.5 expansion(over 400%)
67.3

Li22Si5

Cubic

659.2

82.4

Ref. : A. John Appleby and et al., J Power Sources 163 (2007) 1003-1039

22

Fig. 2. Galvanostatic charge–discharge profiles for micro-Si (10 μm) anode.
J.H. Ryu, J.W. Kim, Y.-E. Sung, S.M. Oh
Electrochem. Solid State Lett., 7 (2004), p.
A306

Cycling behavior of SiOx with different oxygen content and particle size
J. Yang, Y. Takeda, N. Imanishi, C. Capiglia, J.Y. Xie, O. Yamamoto
Solid State Ionics, 152–153 (2002), p. 125

Specific capacity vs. cycle number for nano-crystalline Si and nano-amorphous Si thin film
anodes prepared by thermal vapor deposition. Specific capacity of graphite and bulksilicon anodes also shown
J. Graetz, C.C. Ahn, R. Yazami, B. Fultz
Electrochem. Solid-State Lett., 6 (2003), p. A194

SEM morphology of 250 nm a-Si film on Cu cycled at C/2.5 for (a) 1 cycle, and (b) 30
cyclesJ.P. Maranchi, A.F. Hepp, A.G. Evans, N.T. Nuhfer, P.N. Kumta
J. Electrochem. Soc., 153 (2006), p. A1246

Cycling performance of carbon-coated silicon anodes in 1 M LiPF6 EC:DMC (1:2) at different
water contents present in the electrolyte. In all cases, the ‘exhaustion point’ (last extractionpeak) is centered around 1000 mA h/g
Electrochimica Acta
Volume 48, Issue 11, 15 May 2003, Pages 1579–1587

SiO particle

(b)

(a)

Short/thin CNF

Long/thick CNF

Pyrolytic carbon

(b)
(a)
(b)
(c)

Catalyst
Relative intensity

(a)

(c)
SiO

108

106

104

102

100

98

Binding energy (eV)Figure Schematic model of cocoon shaped composite of silicon monoxide and surficial
carbon nanofiber (SiO-CNF composite)(a)Potential (V) vs. Li/Li+

1.8

1cycle2cycle3cycle

1.5
1.2
0.9
0.6
0.3
0.0
0

600
900
1200
Capacity (mAh/g)

(b)

1.8
Potential (V) vs. Li/Li+

300

1500

1cycle2cycle3cycle

1.5
1.2
0.9
0.6
0.3
0.0
0

300

600
900
1200
Capacity (mAh/g)

1500

Figure Cycle performances with SiO-CNF composite until 3 cycles according to the various amount of CNFs
with Ni (a) or Fe catalyst (b).

Comparison bet. Composite and Mixture
At 1st cycle

900

1335

1253

1180
769

825
450

Coulombic efficiency
65.8

61.9

38.1

0

Composite Composite（Ｎｉ cat.） （Fe cat.）

Mixture
(CNF)

50

52.0

Mixture(KB)

Volume expansion-1

Composite （Fe cat.）

88%

Composite （Ni cat.）68%

Mixture (CNF)

32%

Mixture (KB)

14%

15

25

600

300

0

0

5

10

20

Cycle

 High discharge capacity and coulombic

Electrolyte penetration only (2days)
After charging to 0V

Volume expansion (%)

900

Superiority of the CNF composite

400

301%

300
248%

200

efficiency at 1st cycle
 Excellent cycle performance Lower volume expansion⇒ CNF growth provides spaces to relieve volume

153%
112%

100

st

300

150

Discharge capacity
826

600

1479

Discharge capacity (mAh g )-1Capacity (mAh g )1200

Charge capacity

Coumombic efficiency at 1 cycle

1500

Retention
rate

Cycle performance

124%

126%

expansion and conductivities to improve performances

100
Composite (Fe cat.)

Mixture (CNF)

Mixture (KB)

30

(a)

(b)

(b)

(c)

(c)

Figure 2-12. SEM images of electrode surface after 3 cycles : (a) SiO-CNF composite with Fe catalyst, mixtureof SiO-KB (b) or SiO-CNF (c).

(c)

Problem in Si-CNF composite
Si-CNF composite : CNF growth directly on Si(5um, 1um, 0.4um)
Efficiency : 70.0%

5umSi-CNF(87%)

1.8

1cycle2cycle3cycle

0.3
0.0

1.2
0.9
0.6

1cycle2cycle3cycle

0.3
0.0

0

250

500

750

1000

1250

1500

1750

2000

Potential(V) vs. Li/Li

0.6

+

1.5

+

0.9

Potential(V) vs. Li/Li

Potential(V) vs. Li/Li

1.2

Efficiency : 75%

0.4umSi-CNF

1.8

1.5

+

1.5

Efficiency : 71.9%

1umSi-CNF(88%)

1.8

1.2
0.9
0.6

1cycle2cycle3cycle

0.3
0.0

0

250

500

Capacity (mAh/g)

750

1000

1250

1500

1750

2000

0

Capacity (mAh/g)

250

500

750

1000

1250

1500

1750

2000

Capacity (mAh/g)

Si-CNF model

Problems of Si-CNF composite
 Small particle size, under 1um, is reasonable

Exfoliation

 Poor initial efficiency because of high surface area by CNF growth Binding force bet. Si and CNF are needed Although CNF growth on Si particle of 0.4um (Si-CNF composite), Si-CNF composite didn’t
show improved cycle performance because CNF exfoliated from Si which had no surface acidity.

32

Oxidized Si-CNF composite
To improve surface acidity,
Si particle was oxidized at 700~900℃ for 3 hrs with H2Og.

Schematic model

Oxide film

Performance test
1263

Si

Oxidized
Si

Discharge capacity(mAh/g)

CNF

56.7
AsAs
prepared

Uniformity ↑Adhesion ↑Initial efficiency (%)

442

Prepared

336
24.3

8%

8%酸化

327
21.7

16%

16%酸化

23.0

30%

30%酸化

Extent of oxidation

Adhesive power and uniformity of CNF was improved by surface
oxidized Si, where as charge-discharge performance became poor.
33

Composite of PC coated Si and CNF
As a solution, Pyrolytic carbon (PC) coating on Si particle is suggested.
 Step I : PC is coated on Si particle to improve adhesion between Si and CNF (PCSi).
⇒ The coated PC provide conductivity with Si particles as well as adhesion strength.
 Step II : CNF is grown on PCSi to improve cycle performance Step III : Removal catalyst by HCl treatment
 Step IV : PC is re-coated on PCSi-CNF composite to improve initial efficiency bydecreasing surface area.
No PCSi

Step IFe catalyst
PC coating

Step IIRef.) Carbon 47 (15) (2009) p.3338-3391
Step III
Step IV

Carbon Nanofiber(CNF)

PC re-coating

Si

34

Preparation of PCSi-CNF composite

PC/ or CNF amount (wt. %)

Code
PC

CNF

PC recoating

Condition

Step I

Si-PC

6%

-

-

PC coating(900℃-CH4/He- 30min)

Step II

Si-PC-CNF

6%

93 %

-

CNF growth on PCSi
(580℃-CO/He- 30min)

Step III

Si-PC-CNF-RC

6%

93 %

-

Catalyst removal by HCl

Step IV

Si-PC-CNF-RC-PC

6%

93 %

8%

PC re-coating(900℃-CH4/He- 30min)

-

98 %

-

CNF growth directlyon Si surface

SamplesComparison

Si-CNF35

Analysis of PCSi-CNF composite
SEM & TEM
XRD

C(002)

Si-PC

Si-PC-CNF-RC-PC

Si-PC

Si-PC-CNF-RC-PC

Intensity (cps)Fe
Si-PC-CNF-RC-PC
Si-PC-CNF-RC
Si-PC-CNF
Si-PC
No PCSi

25

35
2 Theta

40

Adsorption amount of N2 /cm (STP) g-130

N2-BET
300

2

-1

3

Si-PC (8 m g )2 -1
Si-PC-CNF (105 m g )2 -1
Si-PC-CNF-RC (107 m g )2 -1
Si-PC-CNF-RC-PC (68 m g )

200

PC

CNF

PC 再コーティング

100

Si

0
0.0

0.2

0.4

0.6

0.8

1.0

Relative pressure, P/P036

Cycle performances of PCSi-CNF composite
Cycle performance

Si-CNF composite
Effi.：75%

Discharge capacity (mAh g -1)

Potential(V) vs. Li/Li +

1.8
1.5

Si

1.2

Exfoliation

0.9
0.6

1cycle2cycle3cycle

0.3
0.0
0

500

1000
1500
Capacity (mAh g-1)

2000

PCSi-CNF

Potential(V) vs. Li/Li+

1.8

Step II

1500

1000

PC被覆なしCNF-Si複合体
Step II
Step III
Step IV

500
0

5

10
Cycle (times)

PCSi -CNF (Fe removal)
Step III

Effi.：76%

15

20

PCSi -CNF (PC re-coating)
Step IV

Effi.：76%

Effi.：79%

1.5
1.2
0.9
0.6

1cycle2cycle3cycle0.3

1cycle2cycle3cycle1cycle2cycle3cycle

0.0
0

400

800
1200
Capacity (mAh/g)

1600

0

400

800
1200
-1
Capacity (mAh g )

1600

0

400

800
1200
-1
Capacity (mAh g )The decreased surface area

1600

37

Cycle performances of PCSi-CNF composite
Capacity at 1st cycle (mAh/g)

SamplesComparison

Samples

Ch

Dis

効率(%)

Si-PC-CNF

1709

1299

76.0

Si-PC-CNF-RC

1674

1272

76.0

Si-PC-CNF-RC-PC

1415

1115

78.8

Si-CNF

2037

1535

75.4

At 20 cycle (mAh/ g)Dis.(max)(mAh /g)Dis

Retention rate (%)

Si-PC-CNF

1317

1051

80

Si-PC-CNF-RC

1318

903

69

Si-PC-CNF-RC-PC

1136

873

77

1535

670

44

Comparison Si-CNF

38

Graphene nanosheets for enhanced lithium storage in lithium ion batteries
Carbon, 47, 2009, 2049–2053, G. Wang et al.

Charge and discharge curves of graphene nanosheets as anode in lithium-ion cells. The
inset is the cyclic voltammograms of graphene nanosheet electrodeSingle wall carbon nanotube paper as anode for lithium-ion battery
Electrochimica Acta
Volume 51, Issue 1, 5 October 2005, Pages 23–28

The charge/discharge profiles of SWNT electrodes: (a) conventional slurry coatedelectrode and (b) “Free standing” electrode.

Preparation and electrochemical properties of Ag-modified TiO2
nanotube anode material for lithium–ion battery
Electrochemistry Communications
Volume 9, Issue 3, March 2007, Pages 425–430

Hybridization of Si/PyC/CNF and NG

20Si/PyC/CNF and NG

50Si/PyC/CNF and NG
1000

900

Discharge capacity (mAh/g)

Discharge capacity (mAh/g)

1000

800
700
600
500
400
300

20Si/PyC/CNF:NG = 5:5
20Si/PyC/CNF:NG = 3:7
20Si/PyC/CNF:NG = 2:8
20Si/PyC/CNF:NG = 1:9
NG

200
100
0

900
800
700
600
500
400
300

50Si/PyC/CNF:NG = 5:5
50Si/PyC/CNF:NG = 3:7
50Si/PyC/CNF:NG = 2:8
50Si/PyC/CNF:NG = 1:9
NG

200
100
0

0

5

10

15

20

25

30

0

5

Cycle

10

15

20

25

30

Cycle

Sample

1st cycle Coulombic
efficiency (%)

Retention ratio(%, 30th/1st )Sample

1st cycle Coulombic
efficiency (%)

Retention ratio(%, 30th/1st )20Si/PyC/CNF:NG=5:5

63.6

86.3

50Si/PyC/CNF:NG=5:5

63.1

81.4

20Si/PyC/CNF:NG=3:7
20Si/PyC/CNF:NG=2:8
20Si/PyC/CNF:NG=1:9

67.5
74.2
80.3

92.6
94.5
97.7

50Si/PyC/CNF:NG=3:7
50Si/PyC/CNF:NG=2:8
50Si/PyC/CNF:NG=1:9

66.9
72.1
77.8

95.4
96.7
98.8

NG

90.0

106.9

NG

90.0

106.9

√ The hybrids of the Si/PyC/CNF and NG showed better cycle-ability than the hybrids of
Si/PyC and NG.
44

Highly stable Si-based multicomponent anodes for practical use inlithium-ion batteries
Jung-In Lee , Nam-Soon Choi and Soojin Park
Energy Environ. Sci., 2012,5, 7878-7882
Interdisciplinary School of Green Energy,Ulsan National
Institute of Science and Technology, Ulsan, Korea 689-798

Synthesis of an Si-based multicomponent from bulk SiO particles via thermal annealing in the presence of NaOH. (a) Schematic
illustration for the conversion of bare SiO to Si–SiO–SiO2 three-components, (b) SEM image of Si-based multicomponents, SEM image (c)and Raman spectrum (d) of carbon-coated Si-based multicomponents, (e) XRD patterns of Si-based multicomponents as a function of
NaOH amount, and (f) calculation of silica and silicon crystallite size as a function of NaOH amountElectrochemical performances of c-SiO and c-Si–SiO–SiO2 three-component electrodes. (a) Voltage profiles of c-SiO (black), c-Si-multi-20–1 (red), c-Si-multi-10–
1 (pink), and c-Si-multi-5–1 (blue). (b) dQ/dV plots of c-SiO and c-Si-multi-20–1 (red) in the first and second cycles. (c) Cycle performances of c-SiO (black), c-Simulti-20–1 (red), c-Si-multi-10–1 (pink), and c-Si-multi-5–1 (blue) at 0.1 C rate. (d) Rate capabilities of c-SiO and c-Si-multi-20–1 electrodes. The discharge rate
was fixed at a rate of 0.1 C

まとめ• Bulk Carbon以外は、長所と共に短所も持っており、まだLi-ion電池用負極としては商品化されていない。
• 今後の研究によって短所が解決できれば、電池の特性はより改善できる。