Selected physicochemical parameters useful for characterizing the metallic lithium electrode exposed to a lithium perehlorate salt in a propylene carbonate solvent are reported as functions of temperature and salt composition. The advantages of using microelectrodes for the measurements are elucidated. Transport parameters governing the electrolytephase limiting current density are found to be independent of salt composition over a concentration range of interest for lithium batteries. The Li-Li + reaction is shown to correspond to classic electron-transfer theory, with a symmetry factor of one-half, as would be expected for a strongly solvated ionic reactant. Simplified equations are derived that allow one to focus on specific aspects of a lithium thin-film battery, demonstrating the utility of the measured parameters for engineering design studies.For the optimal design of lithium batteries, it is necessary to know the transport properties of the nonaqueous electrolyte and the reaction-rate parameters characterizing the electrolyte-electrode interfaces. Using these physicochemical parameters, one can determine which resistance dominates the electrolyte/lithium-electrode portion of the battery, expediting the design of an efficient system.A number of publications ~-~ review early studies concerning the behavior of the lithium electrode in nonaqueous solvents. Microelectrodes are used in this work to investigate kinetic and transport phenomena. Recent studies ~-n have elucidated the virtues of mieroelectrodes for the study of the Li-Li + system. This utility of microelectrodes can be understood by considering the overall behavior of the electrode-electrolyte interface to be represented by Electrochemical reaction: Li + + e-~ Li Chemical reaction: Li + Solvent -> Degradation product If the electrochemical reaction is accelerated relative to the chemical degradation reaction, then the effect of the parallel chemical degradation reaction is reduced. Mieroelectrodes provide a means for studying electrodeposition processes in the ampere/em 2 current-density range, thereby reducing greatly the exposure of deposited lithium to solvent.In addition to providing a tool for investigating the Li-Lt + reaction, the microelectrode is useful for extracting transport parameters from well-defined limiting current plateaus (cf. Fig. 2). However, because very high current densities can be obtained using microeleetrodes, the microelectrode current-potential relation does not represent achievable performance from actual lithium batteries. The lithium electrode in such batteries is usually covered with a resistive surface film, and the overall cell resistance is much larger than that observed in this mieroeleetrode study. During high-rate lithium deposition required for rapid recharge of secondary batteries, metallic lithium does exist on the electrode surface, often in the form of microscopic lithium nodules, and each isolated nodule may be viewed as a mieroelectrode.This communication is organized in the following manner. After a sh...