# Fileset

[d2ta08581j1.pdf](https://mdr.nims.go.jp/filesets/16a87ca5-037d-43fa-815f-cdfc30e71d41/download)

## Creator

[Atsunori Ikezawa](https://orcid.org/0000-0002-8857-7159), [KOYAMA, Yukinori](https://orcid.org/0000-0002-7090-4430), Tadaaki Nishizawa, [Hajime Arai](https://orcid.org/0000-0001-6695-637X)

## Rights

Creative Commons BY Attribution 4.0 International[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[A high voltage aqueous proton battery using an optimized operation of a MoO3 positive electrode](https://mdr.nims.go.jp/datasets/4541ab59-91b5-41e2-bd3b-b62fe21cd38c)

## Fulltext

Supporting Information of  “A High Voltage Aqueous Proton Battery using an Optimized Operation of a MoO3 Positive Electrode”  Atsunori Ikezawa1,*, Yukinori Koyama2, Tadaaki Nishizawa1, Hajime Arai1  1. School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8502, Japan 2.  Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba 305-0044, Japan   * Corresponding Author: (E-mail) ikezawa.a.aa@m.titech.ac.jp   Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2023             Figure S1. A cyclic voltammogram of the MoO3 composite electrode at 10 mV sec–1 in 50 wt% H2SO4 aq.     -100-50050Current / mA0.40.20.0-0.2-0.4Potential / V vs. Ag/AgCl0.60.40.20.0-0.2Potential / V vs. SHE 1st 2nd 3rd                 Figure S2. Schematics of electrochemical three-electrode half-cells for (a) operando X-ray diffraction and (b) charge-discharge measurements and (c) electrochemical three-electrode full-cells. Working electrode(WE)PositiveelectrodeCounterelectrode(CE)Referenceelectrode (RE)WECEREGasketO-ringX-rayNegativeelectrodeREAu filmGasket(a)(b)(c)   Figure S3.  Operando XRD patterns of the MoO3 electrode during reduction-oxidation in the potential range from –0.30 to 0.50 V at 100 mA g–1; contour plots of (a) 1st reduction, (b) 1st oxidation, (c) 2nd reduction, and (d) 2nd oxidation. 3.5 3.0 2.5 2.0x in HxMoO329282726252θ / degree (Mo Kα)3002001000Capacity / mAh g–10.40.20.0-0.2Potential / V vs. Ag/AgCl4003002001000Capacity / mAh g–10.40.20.0-0.2Potential / V vs. Ag/AgCl3.53.02.52.01.5x in HxMoO329282726252θ / degree (Mo Kα)6004002000Capacity / mAh g–10.40.20.0-0.2 Potential / V vs. Ag/AgCl3.02.01.00.0x in HxMoO329282726252θ / degree (Mo Kα)3002001000Capacity / mAh g–10.40.20.0-0.2Potential / V vs. Ag/AgCl3.0 2.5 2.0 1.5x in HxMoO329282726252θ / degree (Mo Kα)(i)(ii)(iii)(iv)(v)(vi)(a) (b)(c) (d)MoO3IIIIIV IIIII IIaIVIIIII IIaIVIIIIIIIaIVphase-IIa 51–2phase-II 42–2phase-IIa 51–2phase-II 42–2phase-IIa 51–2phase-II 42–2      Figure S4. Charge-discharge property of the MoO3 electrode in the potential range from –0.30 to 0.50 V; (a) charge-discharge curves; (b) dQ/dV plots. Dotted circles show the redox couple at around 0.3 and –0.1 V, which is only observed at low-rate reduction-oxidations (< 500 mA g–1) as describe in the manuscript.    0.40.20.0-0.2Potential / V vs. Ag/AgCl4003002001000Capacity / mAh g–10.60.40.20.0 Potential / V vs. SHE 2 A g–1 1 A g–1 500 mA g–1 -3000-2000-10000100020003000dQ/dV0.40.20.0-0.2Potential / V vs. Ag/AgCl 2 A g–1 500 mA g–1(a) (b)   a) From a-axis   b) From c-axis   Figure S5. Schematic views of crystal structure of MoO3. Purple polyhedral and red spheres denote MoO6 octahedra and O atoms, respectively. O1 O3 van der Waals gap O2 O3 van der Waals gap channel    Table S1. Structure parameters of MoO3.  Calculated Experimental [1] a / Å (Error) 3.9105 (-1.27%) 3.9609 b / Å (Error) 15.5116 (+11.94%) 13.8570 c / Å (Error) 3.7304 (+0.95%) 3.6953 Mo (4c) 0.0678 0.0957 1/4 0.075 0.1003 1/4 O1 (4c) 0.5016 0.4385 1/4 0.443 0.4328 1/4 O2 (4c) 0.5150 0.0820 1/4 0.501 0.0770 1/4 O3 (4c) 0.0308 0.2025 1/4 0.068 0.2242 1/4                     Figure S6. Charge-discharge curves of the MoO3 electrode in the potential range from 0.05 to 0.50 V at 100 mA g–1.   0.50.40.30.20.1Potential / V vs. Ag/AgCl250200150100500Capacity / mAh g–10.70.60.50.40.3 Potential / V vs. SHE 1st 2nd 3rd 4th 5th      Figure S7. Ex-situ SEM images of the MoO3 electrodes (upper). EDX maps of Mo element (red) (lower).     As prepared After 1st reduction3 μm 3 μm2 μm 2 μmAfter 30th oxidation3 μm2 μmCrack              Figure S8. Reduction-oxidation curves of the MoO3 electrode at different current densities.     0.50.40.30.20.1Potential / V vs. Ag/AgCl806040200Capacity / mAh g–10.70.60.50.40.3Potential / V vs. SHE 100 mA g–1 200 mA g–1 500 mA g–1 1 A g–1 2 A g–1 5 A g–1              Figure S9. Charge-discharge property of the HxMoO3 (phase-IIa|phase-III)|50 wt% H2SO4|HxMoO3 (phase-III|Phase-IV) full-cell at 200 mA g–1, 1st cycle; (a) cell voltage; (b) potentials of positive and negative electrodes. The capacities were calculated based on the mass of MoO3 in one side of the electrode. The loading masses of the positive and negative electrodes were set to the same value. Before the full-cell construction, the positive and negative electrodes were electrochemically preconditioned with the half cells. The positive electrode was reduced and oxidized in the potential range from 0 to 0.5 V at 200 mA g–1 for 3 cycles, and the cycle was terminated at the reduced state. The negative electrode was reduced and oxidized in the potential range from –0.3 to 0.0 V at 100 mA g–1 for 3 cycles, and the cycle was terminated at the oxidized state. The average discharge voltage and energy density based on the total mass of the active materials are 0.33 V and 15 Wh kg–1, respectively.  0.80.60.40.20.0Voltage / V12080400Capacity / mAh g–10.40.20.0-0.2Potential / V vs. Ag/AgCl12080400Capacity / mAh g–10.60.40.20.0 Potential / V vs. SHE(a) (b)      Table S2. Performances of the full cells shown in Fig. 5 and Fig. S9. The capacities during the first discharging and energy densities were calculated based on the total masses of the active materials.             Cell configuration Capacity / mAh g–1 Average voltage / V Energy density / Wh kg–1MoO3|phase-I|50 wt% H2SO4|phase-III|Phase-IV 36.5 0.48 17phase-IIa|phase-III|50 wt% H2SO4|phase-III|Phase-IV 46.5 0.33 15Reference 1. T. Leisegang, A.A. Levin, J.M. Walter, D.C. Meyer, Cryst. Res. Technol., 2005, 40, 95-105.