上海交通大学杨晓伟团队报道了通过自组装单层调节双电层在Mg金属阳极上稳定固/电解质界面。相关研究成果于2024年10月29日发表在国际知名学术期刊《德国应用化学》。

用高供体数（DN）添加剂调节阳离子溶剂化结构，是在镁阳极上构建稳定的固体电解质界面（SEI）的有效策略，这需要仔细考虑电解质化学和大量添加剂。值得注意的是，阳极附近的双电层（EDL）在SEI形成中起着关键作用，但研究仍然不足。

该文中，研究人员提出了一种新的自组装单层（SAM）策略，利用（三氟甲基）三甲基硅烷（TFTMS，仅2 vol%，1.4 mol%，0.135 mol L^-1），一种低DN但通过吸电子基团（CF₃）具有强Mg金属吸收能力的物质，来调节亥姆霍兹吸收平面的复杂结构。

通过电负性氟（TFTMS的CF₃）和正电性氢（溶剂的CH₃/CH₂）之间的偶极-偶极相互作用，TFTMS削弱了溶剂Mg²⁺的配位，从而增强了阴离子Mg²⁺的相互作用，诱导了稳定致密的SEI，具有优异的电子绝缘性，实现了水平镀/剥离镁。

因此，设计的电解质使对称电池能够稳定循环长达1000小时，并在5mA cm^-2下可逆地镀/剥离镁，它们与各种阴极具有良好的兼容性。更重要的是，SAM策略在其他电解质系统中具有良好的通用性，为促进可充电镁电池的实际应用提供了一条简单有效的途径。

附：英文原文

Title: Regulating Electric Double Layer via Self-Assembled Monolayer for Stable Solid/Electrolyte Interphase on Mg Metal Anode

Author: Zhengqing Fan, Wanyu Zhao, Shang Shi, Mengyuan Zhou, Jiayi Li, Yuan Liu, Zhenghui Pan, Xiaowei Yang

Issue&Volume: 2024-10-29

Abstract: Modulating the cationic solvation structure with high donor-number (DN) additive is an effective strategy to construct a stable solid electrolyte interphase (SEI) on the Mg anode, which necessitates meticulous consideration of electrolyte chemistry and substantial quantities of additives. Notably, the electric double layer (EDL) adjacent to anode is pivotal role in SEI formation yet remains understudied. In this study, we propose a novel self-assembled monolayer (SAM) strategy by utilizing (trifluoromethyl)trimethylsilane (TFTMS, only 2 vol%, 1.4 mol%, 0.135 mol L-1), a low DN but strong Mg metal absorbability through electron-withdrawing groups(CF3), to modulate the complex structure of the Helmholtz absorption plane. Through dipoledipole interaction between the electronegative fluorine (CF3 of TFTMS) and electropositive hydrogen (CH3/CH2 of solvents), TFTMS weakens solventMg2+ coordination and thus enhances anionMg2+ interaction, inducing a stable and dense SEI with superior electronic insulation to realize horizontal Mg plating/stripping. Consequently, the designed electrolytes enable the symmetric cells to cycle stable for up to 1000 hours and reversible Mg plating/stripping under 5 mA cm-2, they show favorable compatibility with various cathodes. More importantly, the SAM strategy has good generality in other electrolyte systems, demonstrating a simple and effective route to promote the practical application of rechargeable magnesium battery.

DOI: 10.1002/anie.202416582

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202416582