A lithium metal foil counter/reference electrode with surface enriched by Li1+xAl alloy

Abstract

The electrochemical characterization of new electrode materials in the lithium battery field is commonly conducted using a simplified two-electrode configuration, known as the “half-cell” concept. However, this approach often overlooks the critical error related to the polarizability of the lithium electrode, especially when the working electrode has a high areal capacity and the half-cell undergoes long-term cycling. In our work, we propose a simple way to improve the properties of the Li electrode, which is using a superstoichiometric Li1+xAl surface enrichment of the metallic lithium foil in situ by direct contact with aluminum foil, serving as a counter/reference electrode. The method eliminates the inhomogeneity of the lithium surface and creates a buffer zone between the highly active lithium electrode and liquid organic electrolytes. The high lithium content in the surface alloy allows the electrode to behave like a lithium electrode while providing low polarization and maintaining a stable potential throughout the long duration of cycling. By implementing this method, we improve the charge/discharge characteristics of high-capacity electrodes and obtain more accurate evaluations of their electrochemical performance.