Liquid-source plasma technology for construction of dual bromine-fluorine-enriched interphases on lithium metal anodes with enhanced performance

Abstract

The electrochemical performance of Li metal anode is closely bound up with the interphase between Li and lithium-loaded skeleton as well as solid electrolyte interphase (SEI) on Li surface. Herein, for the first time, we propose a novel liquid-source CHBr2F plasma technology to simultaneously construct dual bromine-fluorine-enriched interphases: NiBr2-NiF2 interphase on sponge Ni (SN) skeleton and LiBr-LiF-enriched SEI on Li anode, respectively. Based on density functional theory (DFT) calculations and COMSOL multiphysics simulation results, SN skeleton with NiBr2-NiF2 interphase can effectively decrease the local current density with good lithiophilicity. And the LiBr-LiF-enriched SEI on Li surface can function to block electron tunneling and hinder side electrochemical reduction of electrolyte components, thus suppressing the growth of dendrite and facilitating the homogeneous transportation of lithium ions. Consequently, the Li/SN electrodes with modified interphases show remarkable stability with a low overpotential of 22.6 mV over 1800 h at 1 mA cm–2/1 mAh cm–2 and an exceptional average Coulombic efficiency of 99.6%. When coupled with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the full cells deliver improved cycling stability with a capacity retention of 79.5% even after 350 cycles at 0.5 C. This study provides a facile and new plasma method for the construction of advanced Li anodes for energy storage.