With the aim of improving the power of lithium ion batteries,the scientists of Rice University,USA have discovered that graphene might be made useful for high-capacity batteries.Graphene is an allotrope of carbon and it is a flat mono-layer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice.
The experiments by the Rice lab of theoretical physicist Boris Yakobson found that a graphene anode will be able to hold a lot of lithium and accomplish at a voltage which can be used in lithium-ion batteries.Because of its massive surface area and thin structure,battery manufacturers hope to take benefit of graphene to store lithium ions.
However,an obstruction occurred altering all the theories as the ions didn’t stick to graphene very well during experiments.The scientists at the Honda Research Institute looked at the theoretical capacity of an ideal sheet of graphene and also the benefits of its curvature into a nano-tube.They explored that it would improve lithium binding.
Though,the theory didn’t show any significant improvement,the experimentalists were satisfied because their observations were useful for further research.There was no much use with the calculations done involving graphene with defects i.e.,graphenes in which the honeycomb array is interrupted by five- and seven-atom polygons.
“So we decided to explore defects of different types where we replace some carbon atoms with another element that creates more attractive sites for lithium and boron is one of them.”,said prof Boris Yakobson.
A carbon compound in which one-fourth of the carbon atoms are replaced by the boron proved to be a very ideal way to activate the ability of graphene to store lithium.Boron attracts lithium ions into the matrix.The attraction is minimal and the ions can be pulled away from a carbon/boron anode by a more attractive cathode.
Boron in the lattice provides nice binding with exact voltage that increases the capacity two times larger than the graphite which is the most commonly used electrode in commercial lithium-ion batteries.
According to the researchers,a fully lithiated sheet of two-dimensional graphene/boron would have a capacity of 714 milliamp hours per gram.when paired with a commercial lithium cobalt oxide cathode,the energy density will exceed than graphite.
Inspite of its charges and discharges,the material would not radically expand or contract which is undoubtedly better than the present available theories.
The challenge ahead is to find a way to synthesize the carbon/boron compound in large quantities which is not commercially available.If it is found,the future lithium-ion batteries will be available with enormous battery life.