2017 Fiscal Year Annual Research Report
Exotic electrochemical properties of layered compounds with in-plane ordering structure
| Project/Area Number |
17F17046
|
|---|
| Research Institution | The University of Tokyo |
|---|
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)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MORTEMARD DE BOISSE BENOIT 東京大学, 工学(系)研究科(研究院), 外国人特別研究員
|
|---|
| Project Period (FY) |
2017-04-26 – 2019-03-31
|
| Keywords | Oxygen redox / Na-ion batteries / Cathode |
|---|
| Outline of Annual Research Achievements |
As developed in the JSPS proposal, our JSPS project focuses on the development and understanding of new cathode materials involving oxygen redox for Li-ion and Na-ion batteries. During this first year, we focused our research on two materials that were expected to show a significant oxygen contribution: Na4Ir3O8 and Na2Mn3O7.
On one hand, Na4Ir3O8 did not show any reversible oxygen redox properties but showed interesting electrochemistry and structural behavior. Indeed, Na4Ir3O8 is, to our knowledge, the first example of a spinel-based cathode material for Na-ion batteries. Moreover, it showed tremendous structural stability upon cycling due to its very robust IrO6 framework. As a consequence, its volume expansion is lower than 2% upon removal of 3 Na+ per formula unit, making Na4Ir3O8 one of the few zero-strain cathode materials. Our study offers a new direction to develop more stable cathode materials for Na-ion batteries and our findings will soon submitted to a scientific journal.
On the other hand, Na2Mn3O7 showed interesting electrochemical properties owing to significant oxygen redox contribution. Our original approach consisted in incorporating transition metal vacancies in the pristine material in order to generate O orphaned orbitals that contribute to the redox reactions. Moreover, this process occurs at the high voltage of 4.1 V vs. Na and shows an unprecedented low polarization (hysteresis) and stability over time. Our results were just accepted for publication in Advanced Energy Materials (impact factor: 12.12).
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Our JSPS research is progressing according to plan. Oxygen redox in a new system was already reported (see publication section). Other papers in preparation focus on 1) structural and electrochemical characterization of Na4Ir3O8 and 2) the structural evolution of a model cathode material for Na-ion batteries: Na2RuO3.
|
| Strategy for Future Research Activity |
Future work will be divided between two tasks: the completion of current publications and the extension of our work to new materials. Among others, new spinel and layered oxides will be screened to highlight new oxygen redox materials for Na-ion and Li-ion batteries.
|
