Passivation is a phenomenon of all lithium primary cells related to the interaction of the metallic lithium anode and the electrolyte. A thin passivation layer forms on the surface of the anode at the instant the electrolyte is introduced into the cell.
Since passivation begins to occur as soon as the lithium metal battery cell is manufactured, it occurs anywhere the cell or battery pack using the cell is located. Thus passivation is occurring naturally in the battery while in transit, in storage, at the shop, at the rig, or downhole even while operating, if current loads are very low. Why?
Lithium thionyl chloride batteries will passivate continuously, with more increasing level of passivation both as battery temperatures increase and as time extends longer. Operating tools need current pulses to not be adversely inhibited by this natural passivation layer.
On all analyzed lithium samples, our measurements indicate a nanometer-thick inorganic passivation layer consisting of an outer lithium hydroxide and carbonate layer and an inner lithium oxide-rich region. The specific thickness and composition of the passivation layer depend on the treatment before use and the storage and transport conditions.
Higher temperature causes a thicker passivation layer, thus storing at cooler (room) temperature helps mitigate passivation layer growth. Consequently, using fresher batteries helps assure a less resistive passivation layer has formed in the battery. The passivation layer is diminished by appropriate electrical current flow through the cell.
An interfacial passivation combined with self-adaptability strategy was used to improve the electrochemical performance of solid-state batteries. The resulting all-solid-state battery showed high specific capacity and long-term cyclability. 1. Introduction