2017 Fiscal Year Annual Research Report
Materials development toward higher-voltage energy storage devices
| Project/Area Number |
17F17349
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| Research Institution | The University of Tokyo |
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Principal Investigator |
山田 淳夫 東京大学, 大学院工学系研究科(工学部), 教授 (30359690)
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| Co-Investigator(Kenkyū-buntansha) |
LANDER LAURA 東京大学, 工学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2017-11-10 – 2020-03-31
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| Keywords | High-voltage cathode / polyanions / layered oxides / Li-/Na-ion batteries |
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| Outline of Annual Research Achievements |
The goal of this JSPS fellowship is to identify new high-potential cathode materials for Li- and Na-ion batteries. To this end, we studied the electrochemical properties of a heteropolyanionic SO4-PO3F solid-solution Na2Fe(SO4)2-x(PO3F)x.2H2O. The PO3F unit has not been studied as a polyanion for cathode materials so far and we were interested in its inductive effect and its impact on electrochemical performances. Galvanostatic cycling showed with a PO3F substitution we can reach the same redox potential as the pure SO4-based compound, which suggests that PO3F has strong inductive effect. This would open the pathway to a new class of high-potential cathode materials. We furthermore studied the redox behaviour via ex situ Mössbauer following the reversible oxidation/reduction of the Fe3+/Fe2+ couple. A publication is under preparation.
A second project consists of the electrochemical and structural characterization of a Na-based layered oxide containing Ti4+ and Co2+, which displays a large hysteresis during Na (de)intercalation suggesting a spin transition of Co2+ upon oxidation. We are using a multi-angle approach with complementing characterization methods such as ex situ soft and hard X-ray absorption, magnetic measurements and galvanostatic intermittent titration technique (GITT) experiments to understand the underlying redox mechanism. This project is currently on-going.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Experiments and characterization of a novel SO4-PO3F have been mostly completed and the respective paper is currently under preparation.
In addition, experiments and analyses of a layered oxide explaining the reaction mechanism are undergoing with good progress.
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| Strategy for Future Research Activity |
Soft X-ray absorption measurements are scheduled for May on the topic of layered oxides. And further detailed electrochemical and structural studies will be conducted in the next few months. A publication will follow after completing all experiments.
In addition, new polyanionic materials will be examined for their possible electrochemical activity.
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Research Products
(4 results)
