2016 Fiscal Year Annual Research Report
Development of new rechargeable batteries with superconcentrated electrolytes
| Project/Area Number |
16F16051
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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) |
WANG JIANHUI 東京大学, 大学院工学系研究科(工学部), 外国人特別研究員
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| Project Period (FY) |
2016-04-22 – 2018-03-31
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| Keywords | sodium-ion battery / lithium-ion battery / electrolyte / high voltage / safety |
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| Outline of Annual Research Achievements |
We applied a salt-concentrated strategy to explore new electrolytes for Li-ion and Na-ion batteries.
(1) 5 V-class superconcentrated Li-ion electrolytes
Finding a viable electrolyte for next-generation 5V-class Li-ion batteries is of primary importance. By mixing a Li salt with dimethyl carbonate solvent at extremely high concentrations, we obtained an unusual liquid showing a three-dimensional network of anions and solvent molecules that coordinate strongly to Li+ ions. This simple formulation of superconcentrated electrolyte inhibited the dissolution of both aluminium and transition metal at around 5V, and realized a high-voltage LiNi0.5Mn1.5O4/graphite battery that exhibits excellent cycling durability, high rate capability and enhanced safety.
(2) Fire-extinguishing concentrated Na-ion electrolytes
Based on the above achievement on Li-ion batteries, we explored a fire-extinguishing electrolyte for Na-ion batteries with an eye to higher safety. Applying a salt-concentrated electrolyte design, we discovered a fire-extinguishing electrolyte that allows the stable charge-discharge cycling of a hard carbon anode for 1200 cycles (over 15 months) with negligible degradation; this performance is superior to even that of conventional flammable carbonate electrolytes. The unusual passivation character of the concentrated electrolyte coupled with its extinguishing property contributes to developing safe and long-lasting batteries.
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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
Applying salt-concentrated strategy, we have succeeded in developing high-voltage and fire-extinguishing electrolytes. The current progresses match well our expectation in research proposal.
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| Strategy for Future Research Activity |
Based on our research experience, the salt-concentrated strategy is a promising electrolyte design for high-performance electrolytes. Particularly, the concentrated electrolytes using flame-retardant solvents are quite interesting because it can solve the long-standing critical battery safety issue and promote the future large-scale application. Our future work will focus on the fire-extinguishing concentrated electrolytes. We will try them on the high-capacity sodium metal anode and high-voltage sodium-ion cathodes as proposed in the JSPS research plan, meanwhile, apply them in the lithium-ion battery to obtain both high safety and high energy density.
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