Dual‐Functional Electrolyte Additives to Enhance Magnesium Plating/Stripping Performance for Rechargeable Magnesium Metal Batteries With Pure Amine Solvents
Jianhua Xiao, Honggang Wang, Aoqi Yang, Qing Zeng, Jiaming Xu, Xiang Gao, Jiacong Zhou, Jian Tong, Can Liao, Hao Yan, Yinze Zuo, Yun Zheng, Yao Liu, Wei Yan, Jiujun Zhang
Abstract
Abstract Reversible magnesium (Mg) plating/stripping is a key challenge for Mg metal batteries. Hence, a dual‐functional additive, tin(II) fluoride (SnF 2 ), is introduced into the simple Mg salts (Mg(OTf) 2 and Mg(TFSI) 2 ) electrolytes with a pure amine solvent (3‐methoxypropylamine, MOPA). Interfacial characterizations and theoretical calculations reveal that the dissociated SnF 2 can drive the in‐situ formation of a multiphase Sn‐based solid‐electrolyte interphase (SEI) on the Mg anode. Such a robust and magnesiophilic SEI shields the Mg metal from MOPA‐induced corrosion and parasitic reaction, while facilitates the interfacial kinetics of Mg 2+ . Concurrently, the competitive coordination of F − anions from SnF 2 raises the contact ion pairs and further mitigates the MOPA decomposition. As a result, the reversibility of Mg metal anode is successfully enhanced, and Mg//Cu cells maintain over 1000 cycles at 2.0 mA cm −2 with an average Coulombic efficiency exceeding 99.8%. This work offering a promising pathway toward practical application of high‐performance Mg metal batteries.