J. Am. Ceram. Soc., 97 [11] 3374–3377 (2014)
DOI: 10.1111/jace.13267© 2014 The American Ceramic Society

JournalRapid Communication

Nanosized-Layered LiVO2 Prepared from Peroxo-Polyvanadic Acid and Its
Electrochemical Properties
Isao Tsuyumoto,† Yuya Nakakura, and Satoru Yamaki
Department of Applied Chemistry, College of Bioscience and Chemistry, Kanazawa Institute of Technology, 7-1 Ohgigaoka,
Nonoichi, Ishikawa 921-8501, Japan
conventional solid-state reaction, heating the mixture of
V2O5 and Li2CO3 in H2 at 500°C–750°C,13,27,28 whereasoﬀ-stoichiometric Li0.86V0.8O2 was prepared by a hydrothermal reaction between V2O3 and LiOHH2O solution at
180°C.
We have developed new routes for synthesizing metaloxides from peroxo-polymetallic acid obtained by direct
reaction of metallic powders with hydrogen peroxide solution. Our synthetic methods have advantages in preparationof homogeneous and ﬁne powders, because raw materials
are mixed equally at nanometer scale unlike the powder
mixtures for the solid-state reactions. They are appropriate
for the synthesis of nanosized particles as well as metastable phases forming at low temperatures. For example, peroxo-polytungstic acid is obtained by vigorous reaction
between metallic tungsten powder and hydrogen peroxide
solution, and an amorphous precursor is precipitated bymixing an alkali solution with the peroxo-polytungstic
acid.29–32 Heating the precursor at 500°C–700°C yields
alkali tungstates or tungsten bronzes.33–35 Similarly, molybdenum, niobium, vanadium, titanium, and their carbide
powders react with hydrogen peroxide, and yield the corresponding peroxo-polymetallic acids.36–39 Synthesis of nanosized perovskite BaTiO3 and KNbO3 were achieved byheating the salts of peroxo-polytitanic acid and peroxo-polyniobic acid at 650°C, respectively.40,41 A new type of
V2O5 was also synthesized from peroxo-polyvanadate andits discharge/charge properties as a cathode material forrechargeable lithium batteries were investigated.42–45 However, the cathodes for lithium ion batteries must be lithiatedmaterials which act as lithium sources for carbon anodes incharge processes. We aimed at synthesizing nanosized lithium vanadate for cathode materials of lithium ion batteries
through a new route. In this article, we describe the synthesis and electrochemical properties of a nanosized-layered
LiVO2.

Nanosized-layered rock-salt LiVO2 was prepared by a new
method from peroxo-polyvanadic acid. The X-ray diﬀraction
pattern was well ﬁtted with the space group R – 3m in the Rietveld analysis and the crystallite size was estimated at 47 nm.
The electrochemical properties as cathode materials for lithium
ion batteries were investigated. The speciﬁc capacity of LiVO2
was greatly improved to 149 mAh/g under the current densityof 149 mA/g, in comparison with that of the conventional
LiVO2 below 50 mAh/g prepared by the solid-state reactions.

I.

L

Introduction

rock-salt type oxides with composition LiMO2(M = Co, Ni, Mn, etc.) have attracted much attention
as high-energy density cathode materials for lithium
rechargeable batteries.1–3 Because of the expensiveness of the
LiCoO2 cathode presently used, the synthesis and electrochemical properties of its analogues such as LiNiO2,4–8 LiMnO2,9,10 LiNi1/2Mn1/2O2,11 and LiNi1/3Mn1/3Co1/3O212 havebeen investigated extensively as substitutes for LiCoO2.
LiNiO2 shows similar potential curves 0.25 V lower than
LiCoO2 over the entire region, but it is structurally unstable
and tends to release oxygen upon electrochemical delithiation.4–8 Layered LiMnO2 transforms to a spinel phase during
charge processes and shows poorer cycling stability than theideal spinel phase LiMn2O4.9,10
LiVO2 has a layered rock-salt type rhombohedral structure with the space group symmetry R 3m.13 While a great
number of studies have been reported on the electric, electrochemical, and magnetic properties of the Li2O–V2O5 system crystallizing into three phases, namely LiVO3, Li3VO4,and LiV3O8,14–19 there have been a limited number ofreports on the electrochemical properties of the layered
LiVO2.20–26 The speciﬁc capacity of the layered LiVO2 hasbeen reported to be ~50 mAh/g due to an irreversible structural change upon delithiation. In the layered LiVO2 structure, the vanadium and lithium ions occupy the octahedral
sites in the cubic close-packed oxygen lattice, forming alternate layers of vanadium 3a (0, 0, 0) and lithium 3b (0, 0,
1/2). The irreversible structural change is due to the rearrangement of the 3a vanadium ions to both the 3a and 3b
sites upon delithiation. To suppress the structural instability
upon delithiation, an oﬀ-stoichiometric Li0.86V0.8O215 or asolid solution of LiVO2 and Li2TiO317 have been synthesized in earlier reports. LiVO2 has been prepared by the
AYEREDII.

Experimental Section(1) Synthesis
Metallic vanadium powder (0.25 g, 100%, smaller than
75 lm, as received from Kojundo Chemical Laboratory, Saitama, Japan) was dissolved in 100 mL of 30 wt% H2O2 solution (Wako Pure Chemical Industries, Osaka, Japan) at 20°C
with stirring. An orange-yellow transparent solution of peroxo-polyvanadic acid (denoted as V-iPA where iPA stands
for isopolyacid) was obtained in 24 h. After removing insolubles by ﬁltration, we mixed the V-iPA solution with 9.8 mL
of 0.05 M LiOH aq solution at Li/V molar ratio 1. By drying
the mixed solution at 115°C in air for 24 h, we obtained
0.36 g of pale yellow powder of lithium vanadate. By heating
this lithium vanadate at 550°C in air for 24 h and subsequently at 800°C in H2 for 1 h, we obtained black powder of
LiVO2.

M. Bosacka—contributing editor

Manuscript No. 35127. Received June 10, 2014; approved September 5, 2014.
†
Author to whom correspondence should be addressed: e-mail: tsuyu@neptune.
kanazawa-it.ac.jp3374

November 2014

3375

Rapid Communications of the American Ceramic Society(2) Characterization and Electrochemical Measurement
The powder XRD patterns were measured with a diﬀractometer (XD-D1, Shimadzu, Kyoto, Japan) using graphitemonochromatized Cu Ka radiation (k = 0.15406 nm). The Xray proﬁles were collected between 10° and 120° of 2h angles
with a step interval of 0.02°. The crystalline parameters of
the obtained LiVO2 were reﬁned by the Rietveld method
using the RIETAN-FP program.46 The morphology wasobserved by a scanning electron microscope (SEM, JSM5610, JEOL, Tokyo, Japan) with an accelerating voltage of
10 kV. The thermal behavior was investigated by thermogravimetry (TG) and diﬀerential thermal analysis (DTA;
DTG-50, Shimadzu, Kyoto, Japan) at a heating rate of
20°C/min in air.
For charge/discharge measurements, 10.0 mg of LiVO2
was intimately ground with 10.0 mg of acetylene black (AB,Denkikagaku Kogyo, Tokyo, Japan), and the composite,
after mixing with polytetraﬂuoroethylene (PTFE) binder, waspressed onto a nickel mesh with area of 1.0 cm 9 1.0 cm.
Mesocarbon microbeads (MCMB25-28, Osaka Gas Chemicals, Osaka, Japan) was used as a counter electrode and Li
as a reference electrode. A 1 M LiPF6 EC/DEC solution(EC:DEC=1:1 in volume, Kishida Chemical, Osaka, Japan)
was used as an electrolyte. The measurements were carriedout in the galvanostatic mode at 1.49 mA (149 mA/g). All
materials for electrochemical measurements were stored andhandled in an Ar-ﬁlled glove box.
III.

Results and Discussion

The XRD patterns for the samples heated at 115°C in air for
24 h, at 550°C in air for 24 h and at 800°C in H2 for 1 h are
shown in Fig. 1. The dry residue of the solution at 115°C for
24 h was composed of low crystalline LiVO30.5H2O (PDF390371) and other unidentiﬁed compounds. Subsequent heating at 550°C for 24 h yielded white powder sample whose
XRD pattern was coincident with that of the monoclinic
LiVO3 (PDF-251100). By reducing this at 800°C in H2 for
1 h, we obtained black powder sample whose XRD pattern
was coincident with that of the layered LiVO2 (PDF360040). The structural parameters of the LiVO2 from theRietveld reﬁnement are summarized in Table I. The XRD
data were well ﬁtted with the space group R 3m except forsome slight peaks from impurities. This structure is comprised of successive layers of vanadium, oxygen, and lithium
ions normal to c axis, where the vanadium and lithium ionshave ordered arrangements occupying the 3a (0, 0, 0) and 3b(0, 0, 1/2) sites, respectively. The crystallite size was estimated at 47 nm using the Scherrer equation, and this ismuch smaller than the formerly reported results using theconventional solid-state reactions. The SEM image of the
LiVO2 is shown in Fig. 2. The image showed aggregatessmaller than 10 lm and no grown crystals. The aggregatesare considered to consist of secondary particles of the nanosized LiVO2. In short, nanosized-layered LiVO2 was successfully prepared through the new route starting from thereaction between metallic vanadium powder and H2O2 aq.
The TG–DTA curves are shown in Fig. 3. LiVO2 showeda weight increase by 17.9% at 400°C–700°C in air. Thisweight increase is due to the oxidation of LiVO2 and coincident with the theoretical weight increase 17.8% accompaniedby oxidation from LiVO2 to LiVO3. In part of the oxidation
process at 600°C–700°C, the DTA curve showed a broad
endothermic peak in contrast to an exothermic peak at
400°C–600°C, and the increasing rate of the TG curve
declined correspondingly. This is attributed to melting of thesample. Similar behavior of lithium vanadium oxide has beenreported in an earlier study.15 A small endothermic eﬀect
observed at around 212°C is due to the phase transition of
LiVO2, which has been a hot research topic for its unusual
magnetic, electrical, and thermal properties.28 The TG–DTA
and XRD results conﬁrmed that the composition formula ofthe product was LiVO2.
Table I.

Reﬁned Crystallographic Data for LiVO2 Obtained
by Reducing LiVO3 in H2 at 800°C

Hexagonal; space group; R 3m (166) Z = 3
a = 0.28471(3) nm, c = 1.4827(1) nm
Atom

Site

Li
V
O

3b (0, 0, 1/2)
3a (0, 0, 0)
6c (0, 0, z)

Atomic position

z: 0.2562(5)Distance (nm)

Li–Li
Li–O
V–O

0.28470.21130.2002All the occupancies were ﬁxed at unity.

Fig. 2. SEM image of LiVO2 sample prepared from V-iPA
solution.

Fig. 1. XRD patterns of (a) lithium vanadate such as LiVO30.5
H2O obtained as a dry residue of V-iPA solution at 115°C, (b)LiVO3 obtained by heating the lithium vanadate at 550°C in air for
24 h, and (c) LiVO2 obtained by heating the LiVO3 at 800°C in H2
for 1 h.

Fig. 3. TG and DTA curves of LiVO2 sample at a heating rate of
20°C/min in air.

3376

Rapid Communications of the American Ceramic Society

Fig. 4. Charge–discharge curves of LiVO2 sample at a constantcurrent density of 149 mA/g.

The charge–discharge curves of LiVO2 at a constant current density of 149 mA/g are shown in Fig. 4. The potential
showed a roughly linear increase and decrease without plateaus in the charge and discharge curves, respectively, andthe second and third cycles followed almost the same track.
The capacity was 149 mAh/g and this indicates the reversible
extraction and insertion of lithium ions between LiVO2 andLi0.5VO2. We also investigated the charge–discharge cycles
between LiVO2 and Li1–xVO2 for x = 0.6–1.0 to determine
the composition range over which lithium ions are reversibly
extracted and inserted (not shown in ﬁgure). For the cycles
charging up to Li1–xVO2 (x = 0.6–1.0), the charge–discharge
curves showed deviations from those in the former cycle, andthe deviations were increased with increasing x. These results
indicate that lithium ions are reversibly extracted from thepresent LiVO2 up to Li0.5VO2 corresponding to speciﬁc
capacity 149 mAh/g, whereas the extraction of lithium ionsfrom Li1–xVO2 (x > 0.5) brings about an irreversible structural change. An earlier study has reported that vanadium
disordering, migration from the 3a site to the 3b site,
occurred in Li1–xVO2 (x > 0.3) and inhibited reversible lithium extraction and insertion, which resulted in the low-speciﬁc capacities below 50 mAh/g.13 Such irreversibility was
not observed for the present nanosized LiVO2, probably
because the reduction in the particle size enhanced the structural stability and suppressed the disordering. We can saythat the speciﬁc capacity was signiﬁcantly improved to
149 mAh/g by preparing nanosized LiVO2.

IV.

Conclusions

Layered rock-salt LiVO2 with crystallite size 47 nm was successfully prepared through a new route from peroxo-polyvanadic acid. The speciﬁc capacity as a cathode of lithium ion
batteries was 149 mAh/g under rather high current density of
149 mA/g. The capacity was signiﬁcantly improved compared with the conventional LiVO2 obtained by the solidstate reaction (~50 mAh/g), probably because nanocrystallite
is structurally stable during lithium insertion and deinsertion.

References
1

K. Mizushima, P. C. Jones, P. J. Wiseman, and J. B. Goodenough, “LixCoO2 (0 < x < 1): A New Cathode Material for Batteries of High Energy
Density,” Mater. Res. Bull., 15 [6] 783–99 (1980).
2
C. C. Chang, J. Y. Kim, and P. N. Kumta, “Inﬂuence of Crystallite Sizeon the Electrochemical Property of Chemically Synthesized LiNiO2,” J. Electrochem. Soc., 149 [9] A1114–20 (2002).
3
J. Barker, M. Y. Saidi, and J. L. Swoyer, “Lithium Insertion Properties of
the Layered LiMoO2 Made by a Novel Carbothermal Reduction Method,”
Solid State Ionics, 158 [3–4] 261–7 (2003).
4
J. Morales, C. Perez-Vicente, and J. L. Tirado, “Cation Distribution andChemical Deintercalation of Li1-xNi1+xO2,” Mat. Res. Bull, 25 [5] 623–30(1990).
5
Y. Iriyama, T. Abe, M. Inaba, and Z. Ogumi, “Transmission Electron
Microscopy (TEM) Analysis of Two-Phase Reaction in Electrochemical Lithium Insertion Within a-MoO3,” Solid State Ionics, 135 [1–4] 95–100 (2000).
6P. Kalyani and N. Kalaiselvi, “Various Aspects of LiNiO2 Chemistry: A
Review,” Sci. Tech. Adv. Mater., 6 [6] 689–703 (2005).

Vol. 97, No. 11

7
C. Delmas, J. P. Peres, A. Rougier, A. Demourgues, F. Weill, A. Chadwick, M. Broussely, F. Perton, P. Biensan, and P. Willmann, “On the Behavior of the LixNiO2 System: An Electrochemical and Structural Overview,” J.
Power Sources, 68 [1] 120–5 (1997).
8
M. Broussely, F. Perton, P. Biensan, J. M. Bodet, J. Labat, A. Lecerf, C.
Delmas, A. Rougier, and J. P. Peres, “LixNiO2, A Promising Cathode for
Rechargeable Lithium Batteries,” J. Power Sources, 54 [1] 109–14 (1995).
9
Y. Shao-Horn, S. A. Hackney, A. R. Armstrong, P. G. Bruce, R. Gitzendanner, C. S. Johnson, and M. M. Thackeray, “Structural Characterization ofLayered LiMnO2 Electrodes by Electron Diﬀraction and Lattice Imaging,” J.
Electrochem. Soc., 146 [7] 2404–12 (1999).
10
J. Reed, G. Ceder, and A. Van der Ven, “Layered-to-Spinel Phase Transition in LixMnO2,” Electrochem. Solid-State Lett., 4 [6] A78–81 (2001).
11
Z. H. Lu, Z. H. Chen, and J. R. Dahn, “Lack of Cation Clustering in Li[NixLi1/3–2x/3Mn2/3–x/3]O2(0 < x ≤ 1/2)
and
Li[CrxLi(1–x)/3Mn(2–2x)/3]O2(0 < x < 1),” Chem. Mater., 15 [16] 3214–20 (2003).
12
N. Yabuuchi and T. Ohzuku, “Novel Lithium Insertion Material of
LiCo1/3Ni1/3Mn1/3O2 for Advanced Lithium-Ion Batteries,” J. Power Sources,
119–121, 171–4 (2003).
13
L. A. de Picciotto, M. M. Thackeray, W. I. F. David, P. G. Bruce, and J.
B. Goodenough, “Structural Characterization of Delithiated LiVO2,” Mat.
Res. Bull, 19 [11] 1497–506 (1984).
14
A. Reisman and J. Mineo, “Compound Repetition in Oxide-Oxide Interactions: The System Li2O-V2O5,” J. Phys. Chem., 66, 1181–5 (1962).
15
K. West, B. Zachau-Christiansen, S. Skaarup, Y. Saidi, J. Barker, I. I. Olsen, R. Pynenburg, and R. Koksbang, “Comparison of LiV3O8 Cathode Materials Prepared by Diﬀerent Methods,” J. Electrochem. Soc., 143 [3] 820–5(1996).
16
G. Q. Liu, C. L. Zeng, and K. Yang, “Study on the Synthesis and Properties of LiV3O8 Rechargeable Lithium Batteries Cathode,” Electrochim. Acta,47, 3239–43 (2002).
17
S. Das, X. Ma, X. Zong, A. Niazi, and D. C. Johnston, “Phase Relations in the Li2O-V2O3-V2O5 System at 700°C: Correlation With MagneticDefect Concentration in Heavy Fermion LiV2O4,” Phys. Rev. B, 74, 184417(2006).
18
X. M. Jian, J. P. Tu, Y. Q. Qiao, Y. Lu, X. L. Wang, and C. D. Gu,“Synthesis and Electrochemical Performance of LiVO3 Cathode Materials for
Lithium Ion Batteries,” J. Power Sources, 236, 33–8 (2013).
19
W. T. Kim, Y. U. Jeong, Y. J. Lee, Y. J. Kim, and J. H. Song, “Synthesis
and Lithium Intercalation Properties of Li3VO4 as a New Anode Material for
Secondary Lithium Batteries,” J. Power Sources, 244, 557–60 (2013).
20
L. A. de Picciotto and M. M. Thackeray, “Lithium Insertion/Extraction
Reactions With LiVO2 and LiV2O4,” Solid State Ionics, 18–19 [2] 773–7(1986).
21
K. Ozawa, L. Wang, H. Fujii, M. Eguchi, M. Hase, and H. Yamaguchi,“Preparation and Electrochemical Properties of the Layered Material of LixVyO2 (x = 0.86 and y = 0.8),” J. Electrochem. Soc., 153 [1] A117–21 (2006).
22
K. Ozawa, Y. Nakao, L. Wang, Z. Cheng, H. Fujii, M. Hase, and M.
Eguchi, “Structural Modiﬁcations Caused by Electrochemical Lithium Extraction for Two Types of Layered LiVO2,” J. Power Sources, 174 [2] 469–72(2007).
23
L. Zhang, K. Takada, N. Ohta, M. Osada, and T. Sasaki, “Synthesis andElectrochemistry of New Layered (1 x)LiVO2 XLi2TiO3 (0 ≤ x ≤ 0.6) Electrode Materials,” J. Power Sources, 174 [2] 1007–11 (2007).
24
J. H. Song, H. J. Park, K. J. Kim, Y. N. Jo, J. S. Kim, Y. U. Jeong, andY. J. Kim, “Electrochemical Characteristics of Lithium Vanadate, Li1+xVO2,
New Anode Materials for Lithium Ion Batteries,” J. Power Sources, 195 [18]6157–61 (2010).
25
W. T. Kim, Y. U. Jeoug, H. C. Choi, Y. J. Kim, J. H. Song, H. Lee, andY. J. Lee, “New Anode Materials of Li1+xV1 xO2 (0 ≤ x ≤ 0.1) for Secondary
Lithium Batteries: Correlation Between Structures and Properties,” J. Appl.
Electrochem., 41 [7] 803–8 (2011).
26
X. Ma, G. Hautier, A. Jain, R. Doe, and G. Ceder, “Improved Capacity
Retention for LiVO2 by Cr Substitution,” J. Electrochem. Soc., 160 [2] A279–
84 (2013).
27
€
W. R€
udorﬀ and H. Becker, “Uber
Umsetzungen des Vanadin(III)Oxyds
und des Vanadin(IV)Oxyds mit Einigen Metalloxyden (in Germany),” Z. Naturforsch. B, 9, 613–4 (1954).
28
T. A. Hewston and B. L. Chamberland, “A Study of the Ternary Oxide
LiVO2 and Its Anomalous Behavior,” J. Solid State Chem., 65, 100–10 (1986).
29
T. Kudo, “A New Heteropolyacid With Carbon as a Heteroatom in a
Keggin-Like Structure,” Nature, 312 [5994] 537–5 (1984).
30
T. Kudo, H. Okamoto, K. Matsumoto, and Y. Sasaki, “Peroxopolytungstic Acids Synthesized by Direct Reaction of Tungsten or Tungsten
Carbide With Hydrogen Peroxide,” Inorg. Chim. Acta, 111 [2] L27–8(1986).
31
T. Kudo, A. Ishikawa, H. Okamoto, K. Miyauchi, F. Murai, K. Mochiji,
and H. Umezaki, “Spin-Coatable Inorganic Resists Based on Novel Peroxopolyniobotungstic Acids for Bilayer Lithography,” J. Electrochem. Soc., 134 [10]2607–13 (1987).
32
T. Kudo, Y. Sasaki, M. Hashimoto, and K. Matsumoto, “Oxalato Complexes Directly Formed by the Reaction of Interstitial With Hydrogen Peroxide,” Inorg. Chim. Acta, 145 [2] 205–9 (1988).
33
I. Tsuyumoto, A. Kishimoto, and T. Kudo, “Hexagonal Tungsten Bronze
Synthesized From Potassium Peroxo-Polytungstate and Its Electrical Properties,” Solid State Ionics, 59 [3/4] 211–6 (1993).
34
I. Tsuyumoto and T. Kudo, “Humidity Sensor Using Potassium Hexagonal Tungsten Bronze Synthesized From Peroxo-Polytungstic Acid,” Sensors
and Actuators B, 30 [2] 95–9 (1996).

November 2014

Rapid Communications of the American Ceramic Society

35
I. Tsuyumoto and T. Kudo, “Humidity Sensor Using Potassium Hexagonal Tungsten Bronze Synthesized From Peroxo-Polytungstic Acid and Its
Resistivity Change Mechanism,” Mat. Res. Bull, 31 [1] 17–28 (1996).
36
H. Yamada, M. Hibino, and T. Kudo, “Li-Intercalated ReO3-Type
Solid Solutions in the Nb2O5-WO3 System,” Mat. Res. Bull, 34 [6] 955–62(1999).
37
I. Tsuyumoto and K. Nawa, “Thermochromism of Vanadium-Titanium
Oxide Prepared From Peroxovanadate and Peroxotitanate,” J. Mat. Sci., 43[3] 985–8 (2008).
38
I. Tsuyumoto and K. Nawa, “Thermochromism of Titanium-Vanadium
Oxide Thin Films Prepared From Peroxotitanate and Peroxovanadate Solutions,” Solid State Ionics, 179 [21] 1227–9 (2008).
39
I. Tsuyumoto and K. Kobayashi, “Lithium Ion Insertion Properties of
Nanocrystalline Anatase Titanium Oxides Prepared From Peroxo-Polytitanic
Acid,” Solid State Ionics, 255, 60–4 (2014).
40
I. Tsuyumoto, M. Kobayashi, T. Are, and N. Yamazaki, “Nano-Sized
Tetragonal BaTiO3 Powders Synthesized by a New Peroxo-Precursor Decomposition Method,” Chem. Mater., 22 [9] 3015–20 (2010).

3377

41
I. Tsuyumoto, T. Kato, and T. Arai, “Preparation of Nanocrystalline
Perovskite KNbO3 by Peroxo-Precursor Decomposition Method,” Mat. Res.
Bull, 45 [12] 1899–902 (2010).
42
M. Hibino, M. Ugaji, A. Kishimoto, and T. Kudo, “Preparation and Lithium Intercalation of a New Vanadium Oxide With a Two-Dimensional Structure,” Solid State Ionics, 79, 239–44 (1995).
43
M. Ugaji, M. Hibino, and T. Kudo, “Evaluation of a New Type of Vanadium Oxide From Peroxo-Polyvanadate as a Cathode Material for Rechargeable Lithium Batteries,” J. Electrochem. Soc., 142 [11] 3664–8 (1995).
44
T. Watanabe, Y. Ikeda, T. Ono, M. Hibino, M. Hosoda, K. Sakai, and T.
Kudo, “Characterization of Vanadium Oxide Sol as a Starting Material forHigh Rate Intercalation Cathodes,” Solid State Ionics, 151 [1–4] 313–20(2002).
45
D. Imamura, M. Miyayama, M. Hibino, and T. Kudo, “Mg Intercalation
Properties Into V2O5 gel/Carbon Composites Under High-Rate Condition,” J.
Electrochem. Soc., 150 [6] A753–8 (2003).
46
F. Izumi and K. Momma, “Three-Dimensional Visualization in Powder
Diﬀraction,” Solid State Phenom., 130, 15–20 (2007).
h