IN-SITU SCANNING ELECTRON-MICROSCOPY (SEM) OBSERVATION OF INTERFACES WITHIN PLASTIC LITHIUM BATTERIES

Cross-sections of plastic rechargeable Li-cells were observed in a qua si in situ mode by means of a scanning electron microscope. All cells were composed of a composite cathode, containing LiMn2O4 as active mat erial, and of a hybrid polymer electrolyte consisting of a polymer mat rix embedded with a solution of lithium salt. At the negative side, th ree kinds of anodes (Li, Cu and graphite) were successively used. The influence of the current density on the morphology of the Lithium depo sit was studied from these three different configurations. Scanning El ectron Microscopy (SEM) evidences for (1) the accumulation of mossy li thium, and (2) the Li-dendrites growth at the interface between Li and electrolyte are given, and correlated to the poor cell cyclability. T his deterioration of the interface was confirmed by AC-impedance measu rements. (C) 1998 Elsevier Science S.A. All rights reserved.