Graphene-based Li batteries

Graphene has been recently studied as potential replacement of graphite in electrodes for alkali metal-based batteries. In fact, the availability of two surfaces in graphene could bring to an ideal doubling of the  1:6 Li:C ratio obtained by intercalation in graphite. We used micrometer-size graphene flakes deposited onto an anode into an electrochemical cell, and clearly brought to light the very high amount of Li up-take by exposing graphene to Li in controlled ultra-high-vacuum (UHV) conditions, reaching up to 1:2 Li:C ratio. However, this extremely high quantity of Li is also due to Li ions associated to the borders and defects of the graphene flakes, thus unavailable for any cycling.

Porous graphene, on the other hand, thanks to its continuous 2D shape with extremely low defect density, may constitute an ideal scaffold for Li up-take and possibly cycling. A first recent experiment carried out in very controlled and clean UHV conditions, allowed to obtain a 1:4 Li:C ratio, higher than on graphite, although less than on graphene flakes; however, the very low presence of defects in MPG, renders MPG a much better candidate as electrode. Furthermore, we could also determine a much higher absorption content (47% higher than for graphite), thanks to the porous  structure. 

Further characterization is being carried out by charging MPG into an electrode for an electrochemical experiment (in collaboration with the Chemistry Dept of Sapienza University, Roma).