2023 Fiscal Year Research-status Report
| Project/Area Number |
23KF0141
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| Research Institution | The University of Tokyo |
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Principal Investigator |
杉山 正和 東京大学, 先端科学技術研究センター, 教授 (90323534)
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| Co-Investigator(Kenkyū-buntansha) |
JENKINS TRISTRAM 東京大学, 先端科学技術研究センター, 外国人特別研究員
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| Project Period (FY) |
2023-09-27 – 2026-03-31
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| Keywords | Na-ion battery / surface / high-voltage / sulphate / phosphate |
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| Outline of Annual Research Achievements |
Our research, in collaboration with the Yamada-Kitada Lab, focuses on optimizing high-voltage cathode materials for sodium-ion batteries (SIBs) through advanced surface and interface modifications. SIBs offer cost advantages over lithium-ion batteries due to cheaper raw materials, despite their lower energy density (-2.71V Na+/Na vs -3.04V Li+/Li).
We have targeted Alluaudite Na2+2xFe2-x(SO4)3 (NFS) and NASICON Na3Cr2(PO4)3 (NCP) as potential high-performance cathodes. Both materials offer operational voltages of 3.8V and 4.6V, respectively, and are cost-effective, achieving energy densities comparable to current commercial cathodes (400-500Wh/kg). However, NFS suffers from hygroscopicity, and NCP from in-situ electrochemical particle dissolution, impacting structural stability and performance.
Efforts to address these critical issues and enhance the viability and stability of these cathode materials have resulted in the following research achievements to date:
(1) Developed a novel solution-based synthesis for high-purity NFS. (2) Introduced a silane-based surface coating for NFS to reduce hygroscopicity. (3) Conducted comprehensive characterizations via XRD, SEM, FTIR, and Raman Spectroscopy. (4) Investigated the effects of K-ion substitution on NCP’s crystal structure. (5) Discovered new layered Na-K chromium phosphate phase, Na3-xKxCr3(PO4)4 (monoclinic, C2/c) via XRD. (6) DFT modelling of electronic structure for both NFS and NCP.
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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
The progress of Tristram’s research has been marked as good due to the following:
(1) Tristram’s research progress to date has shown effective addressal of the key challenges associated with the material stability for Na2+2xFe2-x(SO4)3 (NFS) and Na3Cr2(PO4)3 (NCP). Progress in this area is not only pivotal for their future practical applications in high-voltage sodium-ion battery chemistries, but also provides new insight on fundamental material issues regarding transition metal sulphate moisture stability (for NFS) and Na/K-ion substitution in NASICON phase materials (for NCP).
(2) The development so far of novel material synthesis and modification methods to address specific issues related to Na2+2xFe2-x(SO4)3 and Na3Cr2(PO4)3 cathode materials has demonstrated good progress towards publishable research works.
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| Strategy for Future Research Activity |
Since we got the achievements described above as scheduled, further research will be conducted as initially planned.
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