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

The effects of temperature on lithium deposition and dissolution on Ni substrate were investigated in 1 mol dm − 3 solutions of lithium bis(perfluoroethylsulfonyl)imide [ LiN ( C 2 F 5 SO 2 ) 2 ] and lithium trifluoromethanesulfonate ( LiCF 3 SO 3 ) 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 ( 0.3 C cm − 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.