Role of Chloride for a Simple, Non-Grignard Mg Electrolyte in Ether-Based Solvents

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• 作者：Niya Sa ; Baofei Pan ; Anumita Saha-Shah ; Aude A. Hubaud ; John T. Vaughey ; Lane A. Baker ; Chen Liao ; Anthony K. Burrell
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 29, 2016
• 年：2016
• 卷：8
• 期：25
• 页码：16002-16008
• 全文大小：460K
• 年卷期：0
• ISSN：1944-8252

文摘

Mg battery operates with Chevrel phase (Mo₆S₈, ∼1.1 V vs Mg) cathodes that apply Grignard-based or derived electrolytes, which allow etching of the passivating oxide coating forms at the magnesium metal anode. Majority of Mg electrolytes studied to date are focused on developing new synthetic strategies to achieve a better reversible Mg deposition. While most of these electrolytes contain chloride as a component, and there is a lack of literature which investigates the fundamental role of chloride in Mg electrolytes. Further, ease of preparation and potential safety benefits have made simple design of magnesium electrolytes an attractive alternative to traditional air sensitive Grignard reagents-based electrolytes. Work presented here describes simple, non-Grignard magnesium electrolytes composed of magnesium bis(trifluoromethane sulfonyl)imide mixed with magnesium chloride (Mg(TFSI)₂-MgCl₂) in tetrahydrofuran (THF) and diglyme (G2) that can reversibly plate and strip magnesium. Based on this discovery, the effect of chloride in the electrolyte complex was investigated. Electrochemical properties at different initial mixing ratios of Mg(TFSI)₂ and MgCl₂ showed an increase of both current density and columbic efficiency for reversible Mg deposition as the fraction content of MgCl₂ increased. A decrease in overpotential was observed for rechargeable Mg batteries with electrolytes with increasing MgCl₂ concentration, evidenced by the coin cell performance. In this work, the fundamental understanding of the operation mechanisms of rechargeable Mg batteries with the role of chloride content from electrolyte could potentially bring rational design of simple Mg electrolytes for practical Mg battery.