In situ Scanning Electron Microscopy (SEM) observation of interfaces within plastic lithium batteries

Cross-sections of plastic rechargeable Li-cells were observed in a quasi in situ mode by means of a scanning electron microscope. All cells were composed of a composite cathode, containing LiMn2O4 as active material, and of a hybrid polymer electrolyte consisting of a polymer matrix embedded with a solution of lithium salt. At the negative side, three kinds of anodes (Li, Cu and graphite) were successively used. The influence of the current density on the morphology of the lithium deposit was studied from these three different configurations. Scanning Electron Microscopy (SEM) evidences for (1) the accumulation of mossy lithium, and (2) the Li-dendrites growth at the interface between Li and electrolyte are given, and correlated to the poor cell cyclability. This deterioration of the interface was confirmed by AC-impedance measurements. © 1998 Elsevier Science S.A. All rights reserved

In situ SEM study of the interfaces in plastic lithium cells

The interfaces of lithium cells were studied upon cycling within a scanning electron microscope (SEM). The LiMn2O4-cathode and the electrolyte consisted of a polymer matrix embedding a solution of LiPF6, while three types of anodes, Li, Cu and graphite, were tested and compared. For each configuration the morphology of the lithium deposit was correlated to the current density. Mossy lithium, at low current, and Li-dendrites, at high current, were observed at the Cu/electrolyte and Li/electrolyte interfaces, while no special morphology was noted at the graphite/electrolyte interface. © 1999 Elsevier Science S.A. All rights reserved