| 研究課題/領域番号 |
17K17559
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| 研究機関 | 北海道大学 |
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研究代表者 |
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| 研究期間 (年度) |
2017-04-01 – 2020-03-31
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| キーワード | Hybrid Material / lithium conductor / interfacial resistance / inorganic buffer layer / all-solid-state battery |
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| 研究実績の概要 |
In this period, different goals were studied:
1. To optimize the composition of the hybrid material to achieve a high lithium ion conductivity. The molar ratio of the precursors: TEOS (tetraethyl orthosilicate), GPTMS (3-glycidoxypropyltrimethosysilane) and EGDE (ethylene glycol diglycidyl ether) with different LiClO4 content were evaluated. The hybrid membrane shows a high ionic conductivity of 10-5 S/cm, transfer number of 0.3 and can be operated up to 5V without evidence of negative oxidation or reduction reactions (at 60 °C show additional oxidation process during the first cycles).
2. To create a low interfacial resistance between the negative electrode side (lithium) and garnet-type solid electrolyte. In this regard, an inorganic layer was used to improve the interfacial resistance at the negative side. The interfacial resistance at the anode side can be reduced in more that one order of magnitude compared without interlayer.
3. To evaluate the electrochemical performance of the all-solid-state battery using the hybrid material. The all-solid-state battery was prepared using the hybrid material between LiCoO2 and garnet solid electrolyte. The cell with a 50% wt. of hybrid material (operated at 60 °C) achieves an initial discharge capacity of 45 mAh/g. Unfortunately, the discharge capacity falls in the subsequent cycles.
4. To evaluate the electrochemical performance of the all-solid-state battery using an inorganic material. In this case, Li2SiO3 prepared by sol-gel process with a conductivity of 10-6 S/cm was used.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
A hybrid organic-inorganic material with adequate lithium conductivity and transport number properties has been performed. Moreover, the hybrid material improves the wettability properties of the surface of the garnet-type solid electrolyte achieving good connectivity (physical contact) between the solid electrolyte and the particles of the active material. Furthermore, alternative surface treatment to improve also the wettability properties of the surface of the garnet-type solid electrolyte with the metallic lithium was developed. Although the all-solid-state battery was constructed with the improved low interfacial resistances at both anodic and cathodic sides, the electrochemical performance of the all-solid-state battery is still limited. The major drawback is finding an active material that can be compatible with the electrochemical properties of the hybrid organic-inorganic material. Other facts to be considered are the morphology and particle size of the active material that can strongly affect the electrochemical performance of the all-solid-state battery.
On the other hand, an all-solid-state battery was constructed using an inorganic buffer layer (Li2SiO3) between solid electrolyte and active material, however, the low ionic conductivity of the Li2SiO3 layer limits the lithium diffusivity at the interface and the battery can only be operated at high temperatures of 100 °C.
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| 今後の研究の推進方策 |
1.To evaluate the electrochemical performance of the all-solid-state battery using the hybrid material with alternative active materials. Active materials with different voltage windows will be evaluated, for example TiS2 and LiFePO4 will be considered. The effect of the morphology and particle size of the active material will be studied. The content of hybrid material in the composite electrode, thickness of composite electrode and thermal treatment will be also studied. The batteries will be evaluated at different temperatures and contrasted with the previous results.
2.To prepare a new hybrid organic-inorganic material. The main propose of the new composition is to improve the stability of the hybrid material at high potential range up to 5V. The new composition will be based on the change of polyethylene oxide chains for polyether ethylene oxide. The polyether chains can increase the stability of the organic part of the hybrid material. In addition, other lithium salts inted of LiClO4 will be evaluated, for example Lithium bis(fluorosulfonyl)imide (LiFSI), where less effect of the anion is expected.
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| 次年度使用額が生じた理由 |
The amount will be used in the next fiscal year for consumables.
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