Stabilization of Li Metal Powder Anodes on Cu Foil Current Collectors Using Thin Carbon Interlayers

Abstract

Due to the highest theoretical capacity, the Li metal anode is considered to be the most ideal anode materials for large-scale batteries, if the problems related to Li dendrite growth can be overcome. Obviously, as most people know well, enlarging the surface area of the Li metal has quite an influence on lower the effective current density to suppress the lithium dendrite growth of lithium metal secondary batteries (LMSB). For this reason, lithium metal powder (LiMP) has attracted much attention for use in electrodes because of its 4.5 times higher surface area compared to lithium foil. However, the electrolyte can be fully penetrated to the LiMP electrode due to its porosity, which leads to galvanic corrosion between Cu foil and LiMP particles. Furthermore, repeated cycling deepens the delamination of lithium particles from Cu foil and results in excess dead lithium particles.Herein, we address this problem by coating the submicron-thickness (~600 nm) carbon interlayer on Cu foil for the LiMP electrode. Despite the LiMP electrode that exists under the electrolyte, the nanoscale carbon interlayer plays an important role in enhancing the adhesive strength between LiMP particle and Cu foil. To confirm the role of the carbon interlayer, we succeeded in quantifying the adhesive strength at the Li/Cu interface for the first time using a surface and interfacial cutting analysis system (SAICAS). Furthermore, the seeding effect of the carbon interlayer in Li/Li symmetric cells and improving electrochemical performance in thin LiMP (40 μm) based cell.