Two-Phase Electrochemical Proton Transport and Storage in α-MoO3 for Proton Batteries

Crystalline structures and lattice water molecules are believed to strongly influence the ability of metal oxides to reversibly and rapidly insert protons in aqueous batteries. In the present work, we performed a systematic analysis of the electrochemical charge storage properties of nanostructured TiO 2 electrodes composed of either anatase or amorphous TiO 2 in a mild buffered aqueous electrolyte. We demonstrate that both materials allow reversible bulk proton insertion up to a maximal reversible gravimetric capacity of 150 mA•h•g -1 . We also show that the TiO 2 crystallinity governs the energetics of the charge storage process, with a phase transition for anatase, while having little effect on either the interfacial charge-transfer kinetics or the apparent rate of proton diffusivity within the metal oxide. Finally, with both TiO 2 electrodes, reversible proton insertion leads to gravimetric capacities as high as 95 mA•h•g -1 at 75 C. We also reveal two competitive reactions decreasing the Coulombic efficiency at low rates, i.e. hydrogen evolution and a nonfaradaic self-discharge reaction. Overall, this work provides a comprehensive overview of the proton-coupled electrochemical reactivity of TiO 2 and highlights the key issues to be solved in order to truly benefit from the unique properties of protons as fast charge carriers in metal oxides.

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Section: 8-10mentioning

confidence: 99%

Evidence of Bulk Proton Insertion in Nanostructured Anatase and Amorphous TiO₂ Electrodes

et al. 2021

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“…Recently, Guo et al [209] investigated the electrochemical insertion of proton in α-MoO3 in acidic electrolyte (i.e., the 4.4 mol L -1 H2SO4 commonly used in lead-acid batteries). Figure 12 presents the electrochemical patterns and operando structure changes of initial proton deintercalation in molybdenum bronzes HxMoO3 (0 ≤ x ≤ 1.68).…”

Section: Electrochemical Lithiationmentioning

confidence: 99%

Growth, characterization and performance of bulk and nanoengineered molybdenum oxides for electrochemical energy storage and conversion

Ramana

Mauger

Julien

2021

Progress in Crystal Growth and Characterization of Materials

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“…11 It is only recently that a broader interest in the reversible insertion of protons in various metal oxides has emerged. 12 So far, the majority of materials examined for their reversible proton insertion properties are hydrated transition metal oxides (mostly layered) such as WO3•nH2O, [13][14][15] H2W2O7, 16 MoO3, [17][18][19] HxIrO4, 20,21 VO2, 8,22 V2O5, 9 and H-titanates. 23,24 In many of these studies, it has been proposed that the presence of ions and/or structural water in the interlayer space or in the tunnel structure of the metal oxide material facilitates the transport of protons within the solid phase.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Bulk Proton Insertion in Nanostructured Anatase and Amorphous TiO2 Electrodes

Makivić¹,

Cho²,

Harris³

et al. 2021

Preprint

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Crystalline structures and lattice water molecules are believed to strongly influence the ability of metal oxides to reversibly and rapidly insert protons in aqueous batteries. In the present work, we performed a systematic analysis of the electrochemical charge storage properties of nanostructured TiO2 electrodes composed of either anatase or amorphous TiO2 in a mild buffered aqueous electrolyte. We demonstrate that both materials allow reversible bulk proton insertion up to a maximal reversible gravimetric capacity of ~150 mA·h·g-1. We also show that the TiO2 crystallinity governs the energetics of the charge storage process, with a phase transition for anatase, while having little effect on either the interfacial charge-transfer kinetics or the apparent rate of proton diffusivity within the metal oxide. Finally, with both TiO2 electrodes, reversible proton insertion leads to gravimetric capacities as high as 95 mA·h·g-1 at 75 C. We also reveal two competitive reactions decreasing the Coulombic efficiency at low rates, i.e. hydrogen evolution and a non-faradaic self-discharge reaction. Overall, this work provides a comprehensive overview of the proton-coupled electrochemical reactivity of TiO2 and highlights the key issues to be solved in order to truly benefit from the unique properties of protons as fast charge carriers in metal oxides.

show abstract

Two-Phase Electrochemical Proton Transport and Storage in α-MoO3 for Proton Batteries

Cited by 59 publications

References 48 publications

Evidence of Bulk Proton Insertion in Nanostructured Anatase and Amorphous TiO₂ Electrodes

Evidence of Bulk Proton Insertion in Nanostructured Anatase and Amorphous TiO₂ Electrodes

Growth, characterization and performance of bulk and nanoengineered molybdenum oxides for electrochemical energy storage and conversion

Evidence of Bulk Proton Insertion in Nanostructured Anatase and Amorphous TiO2 Electrodes

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