Stretchable supercapacitors: Powering wearable electronics

Supercapacitors have a higher power density than batteries and a higher energy density than traditional dielectric capacitors, so they are well developed in various energy storage devices and have a broader prospect. In the past, it was inconvenient for users to wear rigid electronic devices because these electronic devices were simply attached to clothes or connected with conductive fibers, and the hard surface of the electronic devices would rub against human skin and cause discomfort to the human body. In order to solve this problem, people are committed to developing more flexible electronic devices without losing performance.

A research team led by Changyong Cao, professor of mechanical engineering and electrical and computer engineering at Michigan State University, and Jeff Glass, professor of electrical and computer engineering at Duke University, have developed a new type of supercapacitor with good elasticity. It can be stretched to eight times its original size without losing its performance. It will not wear out due to repeated stretching, and only loses a few percentage points of capacity after 10,000 charge and discharge cycles. Based on the performance of the supercapacitor, it is suitable for use in fields such as wearable electronic devices or biomedical devices.

They used stretchable carbon nanotube forests as electrodes and polyvinyl alcohol-potassium chloride as electrolytes to make stretchable supercapacitors. Jeff Glass, professor of electrical and computer engineering at Duke University, and his research team formed a carbon nanotube forest (millions of nanotubes) on a silicon wafer. The nanotubes were 15 nanometers in diameter and 20 to 30 micrometers high. Then, an acrylic elastomer film was coated on top of the carbon nanotube forest. This film acts as an electron collector, allowing the device to charge and discharge faster and better.

Preparation process of stretchable supercapacitor

Professor Changyong Cao of Michigan State University transferred the carbon nanotube forest to a pre-stretched elastomeric substrate, coating side down, and shrunk it to one-quarter of its original size in order to obtain a stretchable supercapacitor with unchanged capacitance and smaller size.

This stretchable supercapacitor has the advantages of large deformation, stable performance, improved specific capacitance and specific energy, and has important application value in wearable devices, electronic skin, bio-integrated electronic devices and other fields.