Surface Control of Lithium Powder by Use of a DET

A new technique for Li powder coating is developed. Surface control of the lithium powders is found to be beneficial in improving their safety and electrochemical properties for use as an anode material in a Li rechargeable battery. LiF, Li2CO3 and wax films can be coated on the Li powder by using a droplet emulsion technique (DET), where fluoride, CO2 and wax, respectively, are used as surfactants during emulsification. The surface films thus formed can be identified by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), focused ion-beam scanning transmission electron microscopy (FIB-STEM) and field-emission scanning electron microscopy (FE-SEM). The electrochemical and the reactive properties of the wax-coated Li powders are observed by using an impedance analysis and photography. The wax coating is found to significantly retard the reactivity of Li powders and, thus, to enhance the stability of the Li powders.