(Invited) Various Strategies Using Protective Coating Layers for High-Performance Lithium Metal Batteries

Abstract

Recently, a consensus has been reached that using lithium metal as an anode in rechargeable Li-ion batteries is the best way to obtain the high energy density necessary to power electronic devices. Challenges remain, however, with respect to controlling dendritic Li growth on these electrodes, enhancing compatibility with carbonate-based electrolytes, and forming a stable solid–electrolyte interface layer.Herein, we suggest a groundbreaking solution to these challenges consisting in the preparation of a Li2TiO3 (LT) layer that can be used to cover Li electrodes via a simple and scalable fabrication method. Not only does this LT layer impede direct contact between electrode and electrolyte, thus avoiding side reactions, but it assists and expedites Li-ion flux in batteries, thus suppressing Li dendrite growth. Other effects of the LT layer on electrochemical performance were investigated by scanning electron microscopy, electrochemical impedance spectroscopy, and galvanostatic intermittent titration technique analyses. Notably, LT layer-incorporating Li cells comprising high-capacity/voltage cathodes with reasonably high mass loading (LiNi0.8Co0.1Mn0.1O2, LiNi0.5Mn1.5O4, and LiMn2O4) showed highly stable cycling performance in a carbonate-based electrolyte. Therefore, we believe that our approach based on the LT layer can boost the realization of high energy density lithium metal batteries and next-generation batteries.Furthermore, functional organic protective layers are helpful to suppress the dendritic growth of Li metal. We would like to introduce two different polymer systems including ferroelectric poly(vinylidene fluoride) fiber mats and elastic polymer, poly(styrene-b-butadient-b-styrene) copolymer for this purpose.