Electrochemical and quartz microbalance technique studies of anode material for secondary lithium batteries

The lithium metal anode for secondary lithium batteries was studied using the electrochemical and the quartz crystal microbalance (QCM) techniques. The solutions studied were: (i) propylene carbonate (PC) containing LiClO4, and (ii) γ-butyrolactone (γ-BL) containing LiPF6. Surface film formation on the electrodes in these solutions was investigated during galvanostatic electrodeposition of lithium. Moreover, the influence of the surface films upon the electrodeposition of lithium and the electrodeposited lithium through surface films were investigated in these solutions. The molecular weights of the species precipitated on the electrode surface were estimated from the QCM data. The deposited lithium on the electrodes made surface films instantaneously in both solutions. The surface films grew continuously in LiClO4/PC even after the electrodeposition of lithium stopped. By contrast, the surface film made in LiPF6/γ-BL was thin and close, and prevented the decomposition of electrolyte and consumption of deposited lithium.