TY - JOUR AU - Hui Wang AU - Xuefei Feng AU - Ying Chen AU - Yi-Sheng Liu AU - Kee Sung Han AU - Mingxia Zhou AU - Mark H Engelhard AU - Vijayakumar Murugesan AU - Rajeev S Assary AU - Tianbiao Leo Liu AU - Wesley Henderson AU - Zimin Nie AU - Meng Gu AU - Jie Xiao AU - Chongmin Wang AU - Kristin A Persson AU - Donghai Mei AU - Ji-Guang Zhang AU - Karl T Mueller AU - Jinghua Guo AU - Kevin Zavadil AU - Yuyan Shao AU - Jun Liu AB -

Conventional electrolytes made by mixing simple Mg2+ salts and aprotic solvents, analogous to those in Li-ion batteries, are incompatible with Mg anodes because Mg metal readily reacts with such electrolytes, producing a passivation layer that blocks Mg2+ transport. Here, we report that, through tuning a conventional electrolyteMg(TFSI)2 (TFSI− is N(SO2CF3)2 −)with an Mg(BH4)2 cosalt, highly reversible Mg plating/stripping with a high Coulombic efficiency is achieved by neutralizing the first solvation shell of Mg cationic clusters between Mg2+ and TFSI− and enhanced reductive stability of free TFSI−. A critical adsorption step between Mg0 atoms and active Mg cation clusters involving BH4 − anions is identified to be the key enabler for reversible Mg plating/stripping through analysis of the distribution of relaxation times (DRT) from operando electrochemical impedance spectroscopy (EIS), operando electrochemical Xray absorption spectroscopy (XAS), nuclear magnetic resonance (NMR), and density functional theory (DFT) calculations

BT - ACS Energy Letters DA - 12/2019 DO - 10.1021/acsenergylett.9b02211 IS - 1 LA - eng N2 -

Conventional electrolytes made by mixing simple Mg2+ salts and aprotic solvents, analogous to those in Li-ion batteries, are incompatible with Mg anodes because Mg metal readily reacts with such electrolytes, producing a passivation layer that blocks Mg2+ transport. Here, we report that, through tuning a conventional electrolyteMg(TFSI)2 (TFSI− is N(SO2CF3)2 −)with an Mg(BH4)2 cosalt, highly reversible Mg plating/stripping with a high Coulombic efficiency is achieved by neutralizing the first solvation shell of Mg cationic clusters between Mg2+ and TFSI− and enhanced reductive stability of free TFSI−. A critical adsorption step between Mg0 atoms and active Mg cation clusters involving BH4 − anions is identified to be the key enabler for reversible Mg plating/stripping through analysis of the distribution of relaxation times (DRT) from operando electrochemical impedance spectroscopy (EIS), operando electrochemical Xray absorption spectroscopy (XAS), nuclear magnetic resonance (NMR), and density functional theory (DFT) calculations

PY - 2020 SP - 200 EP - 206 ST - ACS Energy Lett. T2 - ACS Energy Letters TI - Reversible Electrochemical Interface of Mg Metal and Conventional Electrolyte Enabled by Intermediate Adsorption VL - 5 SN - 2380-8195 ER -