First-Cycle Oxidative Generation of Lithium Nucleation Sites Stabilizes Lithium-Metal Electrodes

Although lithium-metal electrodes have very high capacities, their use as negative electrodes in batteries is associated with stability and safety problems due to formation of dendrites, mossy as well as dead lithium. These problems generally result from the difficulty to ensure that the deposition and stripping of lithium occur homogeneously on the entire electrode surface. As a result, the lithium-metal electrode is gradually transformed into a thick, porous, and poorly performing electrode. It is therefore essential to develop approaches that facilitate the attainment of homogeneous (i.e., 2D) lithium nucleation and growth. It is also important to note that if the lithium electrode is oxidized on the first half-cycle, the formed oxidation pits will control the subsequent lithium deposition step. Herein, it is shown that the performance of lithium-metal electrodes can be straightforwardly improved by introducing a short (e.g., 1 s long) potentiostatic pulse so that the first oxidation step takes place more homogeneously on the lithium surface. This surface activation step gives rise to a large number of preferential lithium nucleation sites facilitating the subsequent attainment of a uniform lithium deposition step. The experimental results indicate that this straightforward pulse approach can significantly increase the lifetime of lithium-metal electrodes.