Electrolyte and Interphase Engineering Through Solvation Structure Regulation for Stable Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) have been viewed as one of the most promising high energy-density battery systems. However, their practical application is hindered by lithium dendrite growth. Herein, an electrolyte regulation strategy is developed to suppress the lithium dendrite growth and enhance the compatibility between electrolyte and electrodes through increasing the concentration of LiNO3 by introducing a high donor number (DN) solubilizer of trimethyl phosphate (TMP). This can not only effectively regulate the solvation structures but also form robust and ionic-conductive SEI films with inorganic-rich inner and organic-rich outer layers to protect Li metal anode. A high compatibility of the engineered electrolyte was obtained with Li metal anodes and high voltage cathodes. As a result, a high Coulombic efficiency of 99.1% and plating/stripping stability of Li metal anode were realized in Li||Cu cells. Furthermore, an excellent performance was demonstrated in Li||LiNi0.83Co0.11Mn0.06O2 (NCM83) full cells and Cu||NCM83 anode-free cells using a high mass-loading cathodes. This work provides a facile electrolyte engineering strategy through introducing a high donor number solubilizer for high energy density LMBs.

Keywords: lithium nitrate, trimethyl phosphate, solvation structures, solid electrolyte
interphases, lithium metal batteries