Wearable electronics are becoming more prominent every day with smart watches and sports bands leading the revolution. Soon, products that are more comfortable to wear could become available in softer materials made partly with an unexpected ingredient: green tea.
In the ACS’ The Journal of Physical Chemistry C, researchers reported a new compact and flexible rechargeable energy storage device. The device is infused with green tea polyphenols and has been designed specifically for wearable electronics.
A big challenge for the soft wearable electronics industry remains powering them with a long lasting source of energy. As supercapacitors meet the power requirements, they could possible fill this role. They can also charge and discharge rapidly many times. Most supercapacitors are however rigid and the compressible supercapacitors developed thus far have run into obstacles. Manufactured with carbon coated polymer sponges, the coating material tends to bunch up and compromise performance.
Kothandam Krishnamoorthy, Guruswamy Kumaraswamy and colleagues wanted to try a different method. Polymer gels were prepared in a green tea extract, which results in the gel being infused with polyphenols from the tea. The polyphenols then convert a silver nitrate solution into a coating of silver nanoparticles that is uniform.
Thin layers of conducting poly (3,4 – ethylenedioxythiophene) and gold were then applied to the coating. The resulting supercapacitor was able to achieve power and energy densities of 2,715 watts per kilogram and 22 watt hours per kilogram respectively. This is enough to power a Bluetooth module, a heart rate monitor, or LEDs. The device’s durability was tested and it was found that it performed perfectly even after having been compressed more than 100 times.