Abstract13 C-carbon black substituted composite LiNi 0.8 Co 0.15 Al 0.05 O 2 cathodes were tested in model electrochemical cells to monitor qualitatively and quantitatively carbon additive(s) distribution changes within tested cells and establish possible links with other detrimental phenomena. Raman qualitative and semi-quantitative analysis of 13 C in the cell components was carried out to trace the possible carbon rearrangement/movement in the cell. Small amounts of cathode carbon additives were found trapped in the separator, at the surface of Li-foil anode, in the electrolyte. The structure of the carried away carbon particles was highly amorphous unlike the original 12 C graphite and 13 C carbon black additives. The role of the carbon additive, the mechanism of carbon retreat in composite cathodes and its correlation with the increase of the cathode interfacial charge-transfer impedance, which accounts for the observed cell power and capacity loss is investigated and discussed. [1,5]. Possible causes of the increase in cathode impedance and irreversible charge/discharge capacity loss include the formation of an electronic and/or ionic barrier at the cathode surface [6,7,8]. This is consistent with our earlier studies [9,10], in which we demonstrated that the non-uniform kinetic behavior of the individual oxide particles was attributed to the degradation of the electronically conducting matrix in the composite cathode upon testing. Carbon additive rearrangement in portions of the tested LiNi 0.8 Co 0.15 Al 0.05 O 2 cathodes and/or thin film formation on the surfaces of carbon and oxide particles is closely linked with the observed isolation of oxide active material.Because the composite cathodes typically consists of an active material, two types of carbon additive, and a binder, suitable instrumental techniques must be applied to obtain lateral resolution comparable to the size and morphology of electrode surface features. In situ and ex situ application of non-invasive and non-destructive microscopies and spectroscopies, including Raman, fluorescence spectroscopy, SEM, and AFM to characterize physico-chemical properties of the electrode/electrolyte interface at nanometer resolution provide unique insight into the mechanism of specific chemical

No abstract

No abstract