Scientists have developed an ink based on graphene nanosheets and also demonstrated that this ink can be used for printing 3D structures. This ink based on graphene can be produced on a large scale at very low costs in an eco-friendly manner. This can result in the wide-scale development of a large variety of printable energy storage equipment.
The group of researchers led by Jingyu Sun and Zhongfan Liu from Soochow University and Beijing Graphene Institute respectively have published a study on their work in ACS Nano journal.
Sun said that their work makes use of the green synthesis of graphene nanosheets that are nitrogen-doped on a salt template with the help of chemical vapour deposition. This gives the room for exploring derived inks in the field of printable energy storage in a greater way.
A major goal in the research of graphene is to make the production of graphene possible at a wide scale assuring both high quality and affordable costs. The production methods used so far resulted in a low quality of graphene with a high number of structural defects and chemical based impurities. Thus it has not been possible to prepare good quality graphene inks.
In this new technique, researchers have used NaCl crystals for growing nitrogen-doped graphene nanosheets with the help of chemical vapour deposition technique as a result of which nitrogen and carbon molecules diffuse on the surface of NaCl crystals. NaCl was chosen due to its wide availability, low cost and high water solubility. For removing sodium chloride, the coated crystals are dipped in water as a result of which NaCl dissolves leaving behind the very pure nitrogen-doped graphene cages. The last step involves giving treatment to the cages with ultrasound as a result of which they transform to two-dimensional nanosheets that are nearly 5-7 layers of graphite in thickness.
These nanosheets have very fewer defects and they are of the perfect size for printing as they are of 5 micrometres in length, whereas the bigger flakes block the nozzle. For putting to test, the actual effectiveness of the ink, a large number of 3D structures were built using the inks. Scientists used the ink as a conductive additive for electrode and then used the composite ink for printing flexible electrodes to be used in supercapacitors with a large power density.
Additionally, scientists also used the ink for printing interlayers for the Li-S batteries. These batteries showed better-enhanced performance with increased conductivity.