Thin films serve as the ideal model systems for fundamental studies of batteries. For a wide range of systems, physical vapor deposition (PVD) techniques are the methods of choice for thin film growth, particularly magnetron sputtering for its high-area capabilities which have led to commercialization, and pulsed laser deposition (PLD) for exploratory science owing to its relative ease and potential for stoichiometric transfer of material from target to substrate. However, stoichiometric transfer is not guaranteed for volatile systems, particularly for materials containing lithium,  which leads to drastic differences in film composition, phase purity, and consequent film properties. This Viewpoint identifies and discusses lithium loss mechanisms during vacuum deposition methods, and with a model system demonstrates that this can occur on a local scale.

Figure caption: A plasma plume generated during pulsed laser deposition of a lithium containing material.