On the Oxidation State of Manganese Ions in Li-Ion Battery Electrolyte Solutions

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• 作者：Anjan BanerjeeYuliya Shilina ; Baruch Ziv ; Joseph M. Ziegelbauer ; Shalom Luski ; Doron Aurbach ; Ion C. Halalay
• 刊名：Journal of the American Chemical Society
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：139
• 期：5
• 页码：1738-1741
• 全文大小：355K
• ISSN：1520-5126

文摘

We demonstrate herein that Mn³⁺ and not Mn²⁺, as commonly accepted, is the dominant dissolved manganese cation in LiPF₆-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn³⁺ fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn³⁺ in the aprotic nonaqueous electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn³⁺ occurs at a very slow rate.