Suppression of formation of lithium dendrite via surface modification by 2-D lithium phosphorous oxynitride as a highly stable anode for metal lithium batteries

Abstract

Lithium phosphorous oxynitride (LiPON) is a thin film solid electrolyte with an amorphous structure and is the most applied material in the thin film battery industry. Herein, LiPON and LiPON/LiPO thin films were directly deposited on a Li foil by the RF sputtering method and evaluated as a protective film to improve the stability of the Li anode. The structural properties of the LiPON and LiPO thin films were confirmed by analytical methods, such as X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, and the ionic conductivity of both thin films was confirmed. Based on these results, cycling evaluation, using Li│Li symmetric cells and LiCoO2│Li cells, confirmed the performance of LiPON and LiPON/LiPO thin films as Li anode protective films. In the cycling evaluation of Li│Li symmetric cells, according to the thickness of the LiPON thin film, the thickness of 200 nm produces the best stability and performance. The 200-nm-thick LiPON protection film and 200-nm-thick LiPON/LiPO protection film were shown to improve the stability of the Li anode in the cycling evaluation of Li│Li symmetric cells and LiCoO2│Li cells. © 2020