In Situ Raman investigations of the Li storage capacity in single-walled carbon nanotube bundles
Materials Research Society (MRS) Fall meeting 2016, Boston, MA, USA
Single-walled carbon nanotubes arranged in spaghetti bundles are investigated as anode materials for Li-ion batteries. Electrochemical experiments are used to measure the charge and discharge curves during the first 5 cycles, and in situ Raman spectroscopy is used to characterize the chemistry of intercalation as well as side interfacial reactions. Raman spectroscopy demonstrates a significantly high capacity from the first discharge, where Li intercalation features and also the signature of side reactions have been clearly observed. However, the capacity is dramatically reduced at the 2nd cycle and is then slightly less affected but still decreases during successive cycles up to the 5th. These experimental results are explained by the density functional theory analyses. In agreement with in situ Raman in the 2nd cycle, the theoretical model demonstrates a much lower capacity of the nanotube bundle compared to graphite. Therefore we attribute the excess capacity measured in the first cycle to the presence of defects and unsaturated edges and to the formation of a solid-electrolyte interphase where both of these effects irreversibly trapping a significant amount of lithium.
 G. Ramos-Sanchez, G. Chen, A. Harutyunyan, and P. B. Balbuena, RSC Adv., 2016, 6, 27260-27266