成果報告書詳細
管理番号20110000000983
タイトル*平成22年度中間年報 次世代自動車用高性能蓄電システム技術開発 次世代技術開発 Li系金属~空気2次電池の性能向上に関する研究
公開日2012/4/6
報告書年度2010 - 2010
委託先名国立大学法人九州大学
プロジェクト番号P07001
部署名スマートコミュニティ部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 現在のLiイオン2次電池では正極と負極に活物質が必要であり、このため重量当たりのエネルギー容量は小さくなる。これに対し、金属~空気電池では、酸化側の活物質は空気なので、通常の電池に比べると、片方の活物質が不要であり、また負極に金属Liを用いるので、単位重量当たりのエネルギー密度が極めて大きく、Li金属~空気電池は最も高エネルギー密度な電池として期待されている。この電池の理論容量は5200Wh/kg-Li(O2を含む、11140Wh/kg-Li(O2を含まず))と他の電池を圧倒して大きな値であり、次世代蓄電池として極めて魅力的な電池である。本研究では、高容量なLi系金属~空気電池の開発を目的としており、特に本年度は、Li系金属~空気電池を用いて、充放電容量:2000mAh/g-cat.の達成、酸化剤:空気の使用、繰り返し:50回以上、空気極反応の解明、負極:Li系合金の使用、安全性の検討達成を目的とする。
本年度は、昨年度に見い出したPd/MnO2 系空気極触媒について、(1)空気の使用のための検討、(2)高性能空気極触媒の開発、(3)揮散しない電解液の検討、(4)合金系負極の検討を目的とした。
英文要約Improvement of Charge/Discharge Capacity of Li-Air Rechargeable Battery
1.Objectives
Recently, lithium-air batteries have been attracting much attention due to its extremely high specific capacity. Li-Air rechargeable battery was reported by using MnO2 for air electrode. In this study, we investigated charge and discharge property of this cell and electrode reaction was analyzed. In this study, we investigated the preparation of MnO2 nanosheet and application to the air electrode of Li air battery.
2.Results in this year
1)Application of zeolite membrane for separation of CO2 and humidity from air
In order to use air for oxidant of Li-air battery, removal of humidity and CO2 is highly requested and we examined the zeolite membrane for removal of water and CO2 from air. It was found that A type zeolite membrane shows a small permeation rate for CO2 and H2O and so by using A type zeolite membrane, we can remove CO2 and H2O from air, which is suitable for oxidant of Li-air batter.
2)Development of active air electrode catalyst
In our previous study, we found that Pd-mesoporous-MnO2 is highly active for air electrode of Li-air battery and so charge and discharge property of Li-air battery using dry air was studied. Although discharge capacity was slightly decreased, stable and reversible charge and discharge property was observed for Li-air batter and capacity of 450 mAh/g-cat was stably sustained over 15 cycles.
In order to increase the discharge capacity, preparation of MnO2 nanosheet was studied and the obtained MnO2 nanosheet was mixed with carbon and applied for air electrode. the maximum discharge capacity was 1490 mAh/g-cat. which was significantly higher than that of conventional secondary batteries and almost twice of or previous study. Although the achieved capacity was slightly smaller than that of objective value (2000mAh/g-cat), efficiency of 75% for charge and discharge is reasonably high and so this study reveals that MnO2 nanosheet is highly interesting from air electrode of Li-air battery.
3)Development of Gel Electrolyte
One reason for decrease in discharge capacity can be assigned to evaporation of electrolyte, and so in this study, gel electrolyte for Li-air battery was studied and it was found that gel electrolyte consisting of 0.8M LiPF6/EC-DEC (3:7) was successfully developed and the discharge capacity of 1200 mAh/g-cat was exhibited by using electrolysis MnO2 mixed with KB carbon for air electrode. Therefore, we successfully achieved the objective in this year.
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