酸素・リドックス・カトドにおける第一サイクル電圧ヒステリシスの上部構造制御
Robert A House1, Urmimala Maitra1, Miguel A Pérez-Osorio1
1Department of Materials, University of Oxford, Oxford, UK.
Nature
|December 10, 2019
まとめ
アルカリに富んだカソッドの電圧ヒステリシスは,その上部構造と関連している. リボンの上部構造はイオンの移動と酸素の放出を抑制し,安定したバッテリー性能を提供し,サイクル中にエネルギー損失を回避します.
科学分野:
- 材料科学
- 電気化学
- 固体化学
背景:
- アルカリに富んだインターケレーションカトッドは,酸化物と移行金属イオンリドックスを利用することで,バッテリーにより高いエネルギー密度を提供します.
- 最初のサイクルにおける電圧ヒステリシス (電池の初期充電-放電中のエネルギー損失) は大きな課題です
- このヒステリシスはしばしば移行金属イオン移動と酸素還元プロセスに起因する.
研究 の 目的:
- 第1サイクル電圧ヒステリシスの決定におけるカトド上部構造の役割を調査する.
- 異なる上部構造を持つ2つの関連したインターカレーションカソッドを比較する:Na0.75[Li0.25Mn0.75]O2とNa0.6[Li0.2Mn0.8]O2.
- 酸素-リドックスカトドの電圧ヒステリシスを緩和するための戦略を特定する.
主な方法:
- 異なる上部構造を持つ2つのインターケレーションカソッド材料の比較分析.
- 電気化学のサイクルと特徴づけ
- 電子構造の変化を検知するX線吸収スペクトロスコーピー.
主要な成果:
- 充電時にNa0.75[Li0.25Mn0.75]O2のハネコブの上部構造が失われ,分子酸素の形成とマンガンイオンの移動につながります.
- この構造の変化は,放電中に不可逆的な電圧損失 (ヒステレス) を引き起こします.
- Na0.6[Li0.2Mn0.8]O2のリボンの上部構造は,マンガンの乱れと酸素形成を抑制し,ヒステリシスを大幅に減少させます.
結論:
- 酸素還元カトドの第一サイクル電圧ヒステリシスは,カトドの上部構造に決定的に依存しています.
- リボンの上部構造は,移行金属の移動と酸素の放出を効果的に抑制し,それによってヒステリーシスを最小限にします.
- リボン型のような特定の上部構造を持つカトッドの設計は,安定した効率的なバッテリー性能を達成するための鍵です.
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