电解质
法拉第效率
材料科学
镁
阳极
无机化学
钝化
盐(化学)
化学工程
电极
化学
有机化学
图层(电子)
纳米技术
冶金
物理化学
工程类
作者
Jianhua Xiao,Xinxin Zhang,Haiyan Fan,Yuxing Zhao,Yi Su,Haowen Liu,Xuanzhang Li,Yipeng Su,Hua Yuan,Ting Pan,Qiyuan Lin,Ludi Pan,Yuegang Zhang
标识
DOI:10.1002/adma.202203783
摘要
Passivation of the Mg anode surface in conventional electrolytes constitutes a critical issue for practical Mg batteries. In this work, a perfluorinated tert-butoxide magnesium salt, Mg(pftb)2 , is codissolved with MgCl2 in tetrahydrofuran (THF) to form an all-magnesium salt electrolyte. Raman spectroscopy and density function theory calculation confirm that [Mg2 Cl3 ·6THF]+ [Mg(pftb)3 ]- is the main electrochemically active species of the electrolyte. The proper lowest unoccupied molecular orbital energy level of the [Mg(pftb)3 ]- anion enables in situ formation of a stable solid electrolyte interphase (SEI) on Mg anodes. A detailed analysis of the SEI reveals that its stability originates from a dual-layered organic/inorganic hybrid structure. Mg//Cu and Mg//Mg cells using the electrolyte achieve a high Coulombic efficiency of 99.7% over 3000 cycles, and low overpotentials over ultralong-cycle lives of 8100, 3000, and 1500 h at current densities of 0.5, 1.0, and 2.0 mA cm-2 , respectively. The robust SEI layer, once formed on a Mg electrode, is also shown highly effective in suppressing side-reactions in a TFSI- -containing electrolyte. A high Coulombic efficiency of 99.5% over 800 cycles is also demonstrated for a Mg//Mo6 S8 full cell, showing great promise of the SEI forming electrolyte in future Mg batteries.
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