成果報告書詳細
管理番号20110000000081
タイトル*平成21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 高圧合成法による次世代高容量正極材料酸化物の材料設計
公開日2012/6/27
報告書年度2009 - 2009
委託先名独立行政法人産業技術総合研究所
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:
[記載事項]
1. 研究開発の内容及び成果等
<研究目標>
自動車用蓄電池の飛躍的な性能向上に資するため、高圧合成技術を利用することにより、次世代高容量正極材料酸化物の新規材料の設計を行う。本事業終了時点で、パック電池レベルでの重量エネルギー密度500 Wh/kgを見通せる高容量正極材料酸化物の探索を行う。具体的には、リチウム負極との組み合わせで酸化物活物質あたり1,200 Wh/kg以上の重量エネルギー密度を有し、20サイクル後に初期放電容量の70%以上の容量を維持可能な高容量正極材料酸化物を見出す。
英文要約Title: Development of High-performance Battery System for Next-generation Vehicles, Materials Design for Next Generation High-Capacity Positive Electrode Oxides by High-Pressure Synthesis Method. (FY2009-FY2010) FY2009 Annual Report
Calcium ferrite type LiMn2O4 shows an excellent electrochemical properties and has obtained by the Na/Li ion exchange reaction using NaMn2O4 having the same crystallographic structure as a starting compound. In order to improve the electrochemical properties, we have tried to substitute the Mn sites by the other transition metal elements. First, we have investigated the synthetic condition of the substituted sodium manganese oxide, including synthetic temperature, chemical composition, and Na/Li ion exchange conditions. Ti, Cr, and Ni were selected and examined as the substitution elements. In the Ti substitution, the calcium-ferrite type Na(Mn1-xTix)2O4 was successfully synthesized for the first time. The synthesis conditions were as follows; Na2O2, Ti2O3, and Mn2O3 used as raw material, x changed within the range to 0.1-1.0, the pressure was 45,000 atmospheres using a cubic-anvil type high-pressure generation apparatus, the annealing temperature was 1050-1400C and annealing time was 1 hour. The high-temperature and high-pressure products were mixed with lithium nitrate, and annealed at 360C for 10 hours. Single phases of calcium-ferrite type Li(Mn1-xTix)2O4 were obtained using the Na/Li ions exchange reaction. The charge-discharge measurements showed the obtained Li(Mn0.9Ti0.1)2O4 electrode shows the initial discharge capacity of 310 mAh/g between 1.0 and 4.8 V, average discharge potential of 2.93 V, and the energy density of 910 mWh/g. These values were able to expect to reach the target property of 1000 mWh/g of energy density and the target discharge potential of 3 V. To understand the structural mechanism of the lithium insertion and extraction reaction, Rietveld analysis using the XRD measurement was carried out for the starting Na(Mn0.9Ni0.1)2O4 sample. Rietveld analysis revealed that Ni atoms selectively occupied one of the Mn sites. XPS measurement was carried out to determinate the electron state for these compounds. From the results of XPS measurement, the valence number of Ni and Ti ions were estimated to be 2 and 4, respectively. The tendencies to be slightly changed were seen in Mn and O. We also investigated new high capacity compound using high-pressure technique.
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