リチウムイオン電池の電解質溶液におけるマンガンイオンの酸化状態について
Anjan Banerjee1, Yuliya Shilina1, Baruch Ziv1
1Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
Journal of the American Chemical Society
|January 26, 2017
まとめ
リチウムイオン電池におけるマンガンのカチオン化学は,電池の充電状態に関係なく,Mn3+,Mn2+ではなく,LiPF6の電解質に溶けたマンガンが優位である. この発見はバッテリーの性能と安定性に 影響を及ぼします
科学分野:
- 電気化学
- 材料科学
- バッテリー技術
背景:
- リチウムイオン電池の電解質に溶けたマンガンの種は,分解メカニズムを理解するために重要です.
- 以前の仮定では,Mn2+が支配的な溶解マンガネスカチオンであり,バッテリーの性能の理論モデルに影響を与えていた.
研究 の 目的:
- リチウムイオン電池のLiPF6ベースの電解質で支配的な溶けたマンガンカチオンを正確に特定する.
- 様々な電気化学的条件 (充電,放電,サイクル) の下でマンガンの種化を定量化する.
- 溶解したマンガンの種の安定性と不均衡性を明らかにする.
主な方法:
- 電子パラマグネティック共振 (EPR) と誘導結合プラズマ (ICP) を用いた組み合わせ分析.
- 溶けたマンガンの平均酸化状態を決定するX線吸収近辺スペクトロスコーピー (XANES).
- 実験結果の検証のための特異化図分析
主要な成果:
- Mn3+は,完全に放電された状態と充電された状態の両方で約80%を占め,サイクルされた細胞で60%を占める支配的な溶けたマンガンカチオンとして特定されています.
- これらの結果は,XANESデータと種化図分析と一致しています.
- Mn3+の分子は時間の経過とともに一定であり,非常に遅い不均衡率が観察される.
結論:
- 一般的に受け入れられている Mn2+の優位性に関する見解は誤りである.Mn3+はこれらの電池電解質の主要な種である.
- アプロティック非水性電解質におけるMn3+の安定性は確認され,リチウムイオン電池におけるマンガンの溶解に関する理解が修正されたことを示唆している.
- これらの発見は,リチウムマンガネートスピネル電池におけるマンガネス関連分解の予測と緩和に重要な意味を持つ.
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