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Preparation, Structure Study and Electrochemistry of Layered H2V3O8 Materials: High Capacity Lithium-Ion Battery Cathode

Sudeep Sarkar,1Arghya Bhowmik,2, 3Jaysree Pan,3Mridula Dixit Bharadwaj,2 Sagar Mitra1*

1 Electrochemical Energy Laboratory, Department of Energy Science and Engineering,

Indian Institute of Technology Bombay, Powai, Mumbai-400076, Maharashtra, India

2 Center for Study of Science, Technology and Policy, 18, 10th Cross, Mayura Street,

Papanna Layout, Nagashettyhalli, RMV II Stage, Bengaluru-560094, Karnataka, India

3Atomic scale modelling and materials, Department of Energy Conversion and Storage,

Technical University of Denmark, Fysikvej Building: 309, 2800 Kgs. Lyngby, Denmark

Tel: + 91-222576-7849. E-mail: sagar.mitra@iitb.ac.in

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Fig. S1. Micrograph of H2V3O8 nano-belts at various temperature conditions (H2V3O8 prepared at

a)-b) 180 °C; c)-e) 190 °C and f) 200 °C).

Fig. S2. a) Experimentally obtained V3O8 structure and b) The final structure of H2V3O8 as

obtained from first-principle structural optimization calculations (Color scheme: gray for V, red

for O and white for H).

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Fig. S3. Correlation between charge transfer to oxygen during lithiation and electrochemical

potential.

As mentioned, water intercalation happens as hydroxyl group rather than water molecule itself.

Thus, to locate hydrogen atom is necessary to understand the structure. However, theoretical

methods for crystal structure solution fail to pinpoint position of hydrogen atoms in this material.

Thus, the position of oxygen atom associated with them was captured, without any specifics of

which oxygen atom comes from the intercalated water. We took a simple approach of first

locating intercalation sites in the experimentally obtained [1] crystal structure and the oxygen

atoms next to these sites which might come from intercalated water. Next we attached two

hydrogen atoms to each of the oxygen atoms which are symmetrically equivalent and performed

structural optimization. This was done for set of symmetry equivalent oxygen atoms together.

We used the structure with lowest energy obtained through this process. For representing on site

correlation in d-orbital of vanadium atoms, Hubbard U of 5.0 eV was used following the

theoretical work in vanadium oxides [2].

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Fig. S4. XRD of a) H2V3O8 material prepared at 190 C for 5 h; b) Li1H2V3O8; c) Li3H2V3O8, d)

Li3.5H2V3O8 (1.5 V) and e) H2V3O8 (Charged state, 4.0 V) (Charge-discharge was performed at

10 mA g-1).

Table S1. Crystallography parameter of H2V3O8 during insertion/de-insertion process.

Material a

(Å)

b

(Å)

c

(Å)

H2V3O8 [1] 16.9

3

9.36 3.64

H2V3O8 (Pristine) 16.6

3

9.23 3.60

Li1H2V3O8 16.6

8

9.42 3.54

Li3H2V3O8 16.6

5

9.40 3.54

Li3.5H2V3O8 16.7

4

9.28 3.55

H2V3O8 (Charged State_4.0 V) 16.4

0

9.40 3.54

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Fig. S5. Schematic figure showing gradual lithiation process and voltage drop in LixH2V3O8.

Fig. S6. XRD of sample prepared at 190 °C for 1 h (scan from 5 °-50 ° (2θ)).

The sample prepared at 190 °C for 1 h forms V2O5.nH2O which is accordance with JCPDS file

no. 40-1296. The variation of intensity in the XRD peaks depends on surfactant/chelating agent

used in the synthesis [3].

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Fig. S7. FEG-TEM images of H2V3O8/V2O5.nH2O nano-belts prepared at 190 °C by varying time

(V2O5.nH2O prepared at a)-b) 1 h; H2V3O8 prepared at c)-e) 3 h; f)-g) 5 h and h)-i) 7 h of reaction

time).

Fig. S8. a) XPS survey scan of H2V3O8 (Ag peaks appears from the conductive additive while

performing XPS) and b) XPS spectrum for lithium of LixH2V3O8.

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Fig. S9. EIS of H2V3O8 during a) Discharge; b) Charge; Fitted data during c) Discharge; d)

Charge (190 °C for 5 h) and e) Equivalent circuit [4] (charge-discharge was performed at 10 mA

g-1).

References

1. Y. Oka, T. Yao, N. Yamamoto, Structure determination of H2V3O8 by powder X-ray

diffraction, J. Solid State Chem. 89 (1990) 372-377.

2. G. Keller, K. Held, V. Eyert, D. Vollhardt, V. I. Anisimov, Electronic structure of

paramagnetic V2O3: strongly correlated metallic and mott insulating phase, Physical

Review B. 70 (2004) 205116-14.

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3. A. Qian, K. Zhuo, M. S. Shin, W. W. Chun, B. N. Choi, C.-H. Chung, Surfactant effects on

the morphology and pseudocapacitive behavior of V2O5·H2O, ChemSusChem, DOI:

10.1002/cssc.201403477.

4. S. Sarkar, S. Mitra, Li3V2(PO4)3 addition to the olivine phase: understanding the effect in

electrochemical performance, J. Phys. Chem. C 118 (2014) 11512-11525.

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