Enhanced electrochemical lithium storage by graphene nanoribbons

Herein, we report the electrochemical Li intake capacity of carbonaceous one-dimensional graphene nanoribbons (GNRs) obtained by unzipping pristine multiwalled carbon nanotubes (MWCNTs). We have found that nanotubes with diameters of ∼50 nm present a smaller reversible capacity than conventional mesocarbon microbead (MCMB) powder. Reduced GNRs improve the capacity only marginally over the MCMB reference but present a lower Coulombic efficiency as well as a higher capacity loss per cycle. Oxidized GNRs (ox-GNRs) outperform all of the other materials studied here in terms of energy density. They present a first charge capacity of ∼1400 mA h g^-1 with a low Coulombic efficiency for the first cycle (∼53%). The reversible capacity of ox-GNRs is in the range of 800 mA h g^-1, with a capacity loss per cycle of ∼3% for early cycles and a decreasing loss rate for subsequent cycles.