Synthesis and Electrochemical Performance of the Orthorhombic Li2Fe(SO4)2 Polymorph for Li-Ion Batteries

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• 作者：Laura Lander ; Marine Reynaud ; Gwena毛lle Rousse ; Moulay T. Sougrati ; Christel Laberty-Robert ; Robert J. Messinger ; Micha毛l Deschamps ; Jean-Marie Tarascon
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：July 22, 2014
• 年：2014
• 卷：26
• 期：14
• 页码：4178-4189
• 全文大小：785K
• ISSN：1520-5002

文摘

To enhance the safety, cost, and energy density of Li-ion batteries, significant research efforts have been devoted to the search for new positive electrode materials that exhibit high redox potentials and are composed of low-cost, earth-abundant elements. Sulfate chemistry has yielded promising results for iron-based polyanionic electrode materials using the Fe^III+/Fe^II+ redox couple, including the recent discovery of a monoclinic marinite Li₂Fe(SO₄)₂ phase (3.83 V vs Li⁺/Li⁰). Here, we report the ball-milling synthesis and electrochemical properties of a new orthorhombic polymorph of Li₂Fe(SO₄)₂, which reversibly reacts with lithium through a two-step redox process (3.73 and 3.85 V vs Li⁺/Li⁰) with an overall sustained capacity of about 90 mAh/g. Using similar synthesis conditions, the cobalt-, zinc-, magnesium-, and nickel-based orthorhombic analogues were also obtained, though no electrochemical activity was observed for these phases. Overall, our results demonstrate that polymorphism can play a crucial role in the search for new battery electrode materials and emphasize the need to understand and master synthetic control.