成果報告書詳細
管理番号20110000000674
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 高容量・低コスト新規酸化物正極材料の研究開発
公開日2012/6/27
報告書年度2010 - 2010
委託先名独立行政法人産業技術総合研究所 株式会社田中化学研究所
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:
1. 研究開発の内容及び成果等
<研究目標>
次世代クリーンエネルギー自動車用リチウムイオン電池の高エネルギー密度化・高出力密度化に資するため、低コストかつ資源的に豊富な元素(Mn、Fe、Ti 等)を主体とする新規高容量酸化物正極材料を開発する。より具体的には、現行の正極材料の約2倍(1 時間率放電において1000Wh/kg(負極をLi 金属と仮定した場合))のエネルギー密度を有し、かつ1/20 時間率放電において1 時間率放電の容量の80%以上を維持する新規正極材料を見出す。
最終的(H23 年度終了時)には、小型実用単電池作製及び実用化促進のため、上記性能を有する正極材料の品質安定化技術(電池メーカーでの評価が可能な数kg オーダー)を検討し、小型実用単電池あたりの重量エネルギー密度250 Wh/kg を達成する。また、重量出力密度3125 W/kg を見通すための高出力化技術を確立する。上記小型単電池の性能値により、最終目標である電池パックあたり重量エネルギー密度200 Wh/kg、重量出力密度2500 W/kg を見通す。上記目標を達成するために以下の研究開発テーマを設定し実施した。
英文要約Title: Development of High-performance Battery System for Next-generation Vehicles, Elemental technology development, R & D of novel and high-capacity positive electrode material consists of low-cost constituent oxides (FY2007-FY2011) FY2010 Annual Report

Novel positive electrode materials, Li2MO3 (M=Mn and Fe or Ti) and Li0.44+xMO2 (M=Mn and Ti) with high energy density are investigated by combining various synthetic techniques. To operate typical voltage range of Li2MnO3 positive electrode (2.0-4.8 V), novel two kinds of Li2MO3 positive electrode materials (Fe and Ni or Co substituted Li2MnO3) were synthesized by co-precipitation - hydrothermal - calcination method. At an optimized chemical composition and preparation condition, Li1+x(Fe0.2Ni0.2Mn0.6)1-xO2 exhibited high-initial charge and discharge capacity above 250 mAh/g at 40 mA/g and long cycle life (70% of discharge capacity was retained at 100th cycle). Li1+x(Fe0.3Co0.3Mn0.4)1-xO2 exhibited high-initial charge and discharge capacity above 200 mAh/g and long cycle life (65% of discharge capacity was retained at 50th cycle). "Self-activated" Li1+x(Mn0.5Ti0.5)1-xO2 (0 < x <1/3) positive electrode materials, which contain partially-reduced Mn cations, were prepared using spark-plasma-sintering (SPS) process. The Mn K-edge XANES spectra showed the reduction of Mn valence by the SPS-treatment (>650C). The electrochemical tests showed higher discharge capacity (ca. 215 mAh/g) and higher averaged discharge voltage (ca. 3.06 V), as compared with those of the non-reduced samples. Cu-substituted Li0.44+xMO2 (M=Mn and Cu) samples were synthesized by ion-exchange and additional lithiation processes using Na0.44MO2 as starting materials. The starting Na0.44MO2 was synthesized by solid state reaction at 800C. The prepared Li0.44+xMn0.97Cu0.03O2 demonstrated high discharge voltage of 3.70 V and the capacity retention rate of 85% after 50 cycles in the voltage range from 4.8 V to 2.5 V. The layered rocksalt-type LixMn1-yTiyO2 samples were prepared by means of low temperature ion-exchange from NaxMn1-yTiyO2 precursor at 80C. The prepared LixMn1-yTiyO2 with y=0.11 sample exhibited high initial discharge capacity beyond 330 mAh/g between 5.0 and 1.5 V with a current density of 30 mA/g at 25C. The Li1+x(Fe0.2Ni0.2Mn0.6)1-xO2 positive electrode material was produced by Tanaka Chem. Co. from spherical agglomerate of constituent metal hydroxide for improving electrode density of practical film electrode. The developed positive electrode exhibited high initial charge (300 mAh/g) and discharge (220 mAh/g) capacities between 2.0 and 4.8 V which was comparable to above electrochemical data of AIST. The film electrode density reached 1.94 g/cm3. The positive electrode powder will be prepared from massive batch (3 kg/month) of metal hydroxides by co-precipitation - calcination method. We have investigated the charge-discharge mechanism in the first cycle and the origin of its high charge-discharge capacity for Li1.2Mn0.4Fe0.4O2 positive electrode. Results reveal that oxygen loss occurs in the entire region of the Li1.2Mn0.4Fe0.4O2 particles during the first charge. Nanodomains of Mn-Li ferrites with a spinel structure start to be formed along the particle surfaces before 50% state of charge. During the first discharge, part of extracted oxygen is reinserted preferentially into the Fe-rich nanodomains as oxide ions, and the proportion of the spinel nanodomains decreases. The origin of the high charge-discharge capacity might be ascribed to the participation of the oxide ions and neutral oxygen species in charge compensation by incorporation of the LiFeO2 component into Li2MnO3. Irreversible capacity at the first cycle can be caused by the irreversible loss of oxygen during the charge and irreversible structural changes throughout the cycle.
ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る