Deterioration Analysis of Lithium Metal Anode in Full Cell during Long-Term Cycles

The cross-section of the lithium metal anode was observed by a scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDS) in order to investigate the morphological change of lithium metal anode during long-term cycles in the laminate-type lithium metal rechargeable battery. Electrochemical impedance spectroscopy was carried out to confirm the resistance of the cell. Metallic lithium was consumed by the side reactions at the interface between electrolyte and deposited lithium, resulting in low coulombic efficiency (CE). Film-shape deposits, which were considered to be the surface films formed by side reactions at the interface between electrolyte and deposited lithium, were observed in the cycled anodes. The resistive surface films is considered to inhibit the dissolution and deposition of lithium. Furthermore, it was observed that the layer consisting of the film-shape deposits became thicker with increasing cycle number. It is considered that the thick layer consisting of the film-shape deposits inhibits the mass transfer, resulting in the degradation of the anode. (c) 2019 The Electrochemical Society.