A future of soft robots that wash your dishes and smart T-shirts that power your cell phone may depend on the development of stretchy power sources.

In a step toward such soft and wearable electronics, a team of researchers from Nanyang Technological University, in Singapore, has now produced a stretchy micro-supercapacitor using ribbons of graphene.

This stretchy supercapacitor, made from graphene, could help spur the development of wearable electronics. Image credit: Xiaodong Chen, Ph.D.“Most power sources, such as phone batteries, are not stretchable. They are very rigid,” says Xiaodong Chen, associate professor in the university's School of Materials Science and Engineering. “My team has made stretchable electrodes, and we have integrated them into a supercapacitor, which is an energy storage device that powers electronic gadgets.”

Supercapacitors, developed in the 1950s, have a higher power density and longer life-cycle than standard capacitors or batteries. As devices have shrunk, so too have supercapacitors, bringing to the fore a generation of two-dimensional micro-supercapacitors that are integrated into cell phones, computers and other devices. However, these supercapacitors have remained rigid and are thus a poor fit for soft materials that need to be able to elongate.

To develop a micro-supercapacitor from graphene that is stretchable, the researchers’ first step was to make graphene micro-ribbons. The researchers then created a stretchable polymer chip with a series of pyramidal ridges. The graphene ribbons were placed across the ridges, creating a wave-like structure.

The design allows the material to stretch without the graphene electrodes of the superconductor detaching, cracking or deforming. In addition, the team developed kirigami structures, variations of origami folds, to make the supercapacitors 500% more flexible without decaying their electrochemical performance.

As a test, Chen successfully powered an LCD from a calculator with the stretchy graphene-based micro-supercapacitor. While the current version only stores enough energy to power LCD devices for a minute, future research will focus on increasing the electrode’s surface area so it can hold more energy.