The rising demand for portable electronics, e-textiles, and IoT devices has driven the need for lightweight technologies and miniaturized energy storage solutions. Graphene-based nanomaterials are at the forefront of extensive research due to their chemical stability, high surface area, strength, flexibility, and superior thermal and electrical conductivity.
Supercapacitors, known for their fast charge-discharge rates, long lifespan, and simple structure, are becoming essential for energy storage in electronics, electric vehicles, and biomedical devices. They operate by storing charges through the adsorption and desorption of ions at electrode interfaces, achieving power densities over 10,000 W/kg. Microsupercapacitors, which are smaller and lighter versions, are particularly suitable for portable and wearable electronics, offering even higher power densities.
The high electrical conductivity and surface area of specific graphene materials make them ideal for these applications. However, current production methods present toxicity and scalability issues that have limited their widespread use. Additionally, the materials need to comply with the requirements of deposition techniques able to guarantee reasonable production throughput.
Now, INL researchers have developed a sustainable approach to produce an electrically conductive, graphene-based paste suitable for fabricating flexible devices.
The results are reported in the journal Nano Energy (“Sustainable graphene production for solution-processed microsupercapacitors and multipurpose flexible electronics”), in a paper by INL researchers, in collaboration with colleagues from Sapienza University of Rome and Instituto Superior Técnico in Lisbon. The work demonstrates an innovative method for scalable, cost-effective, and environmentally friendly production of high-quality graphene materials, paving the way for advanced applications in energy storage and flexible electronics. Siva Sankar Nemala, Research Fellow at INL and first author of the paper, explains the methodology, “our approach is based on the exfoliation of graphite in water by using high-shear mixing and high-pressure airless spray techniques, which are carefully optimised to obtain highly concentrated and stable dispersions of graphene. The graphene materials are then combined with carbon black and a natural binder to form an eco-friendly composite paste that can be used to fabricate fully flexible and high-performance microsupercapacitors”.
“These microsupercapacitors demonstrate very high capacitance and energy density, providing exceptional coulombic efficiency and cyclability (~99% after 10,000 cycles), mechanical flexibility, and the possibility of serial/parallel integration without metal-based interconnects for high-voltage and high-capacitance outputs. As a result, these lightweight and versatile devices have enormous potential for electronic applications,” says Andrea Capasso, Staff Researcher at INL and coordinator of the study.
Capasso further remarks, “We have developed a one-kind-fits-all paste for innovative electronic devices that can be fabricated by low-cost techniques such as blade coating and screen printing, making a significant step towards commercial production.”
The versatility and broad application potential of this nanocarbon-based paste have been demonstrated by the researchers, who fabricated an array of diverse devices, including efficient electromagnetic interference shielding coatings and reliable wearable strain sensors integrated in textiles.