In Situ Atomic Force Microscopy Study on Lithium Deposition on Nickel Substrates at Elevated Temperatures

Abstract

The effects of temperature on lithium deposition and dissolution on Ni substrate were investigated in 1 mol dm−31 mol dm−3 solutions of lithium bis(perfluoroethylsulfonyl)imide [LiN(C2F5SO2)2][LiN(C2F5SO2)2] and lithium trifluoromethanesulfonate (LiCF3SO3)(LiCF3SO3) dissolved in propylene carbonate. The cyclability for lithium deposition and dissolution was greatly improved at elevated temperatures of 60 and 80°C. The surface morphologies of lithium deposited on Ni substrates at different temperatures were observed by in situ atomic force microscopy (AFM). The surface film formed at room temperature and 40°C was inhomogeneous, and large masses of deposits appeared after prolonged deposition (0.3Ccm−2).(0.3Ccm−2). In contrast, closely packed, uniform surface film consisting of particle-like deposits of 100-200 nm diam was formed at 60 and 80°C, and no significant morphology changes were observed after prolonged deposition and even after dissolution. It was concluded that the uniformity and self-reparability of the surface film, and an enhanced surface diffusion of lithium atoms suppressed dendritic deposition and improved the cycling characteristics at the elevated temperatures. © 2002 The Electrochemical Society. All rights reserved.