One of the obstacles to the widespread acceptance of electric vehicles (EV) is the battery charge time. At the moment, it’s too long. Supercapacitors, on the other hand, have to potential to enable an EV to charge in minutes (instead of hours). However, researchers are still working out a few kinks, such as their lifespan.
Texas A&M University researchers have reported on a radically new design for a supercapacitor made with plant-based materials. So, it’s better for the environment too, not just the driver. Furthermore, the team demonstrated that the device is also cost-effective, lightweight, and flexible.
Supercapacitors store charge on metal plates known as electrodes. They are quite versatile and can be made in different shapes, sizes, and designs, as well as with other materials. In this new study, the team used manganese dioxide nanoparticles for designing one of the supercapacitor electrodes.
Oscar S. Wyatt Jr. Professor Hong Liang, from the J. Mike Walker ’66 Department of Mechanical Engineering, said:
Manganese dioxide is cheaper, available in abundance, and is safer compared to other transition metal oxides, like ruthenium or zinc oxide, that are popularly used for making electrodes. But a major drawback of manganese dioxide is that it suffers from lower electrical conductivity.
To resolve the issue of manganese dioxide’s lower electrical conductivity, the team looked to make use of lignin – a natural polymer that gives trees and other plants their rigidity. The material is a waste product of the paper manufacturing industry, which is generated in massive amounts. There have been some exciting breakthroughs in efforts to recycle the polymer into other products. One, for example, involved a group from The University of Tokyo who used lignin to develop a stronger bendable concrete.
https://www.youtube.com/watch?v=McCNMLE8Mw0
Past research has shown that lignin, combined with metal oxides, enhances the electrical performance of supercapacitor electrodes. But none focused on integrating it with manganese dioxide, which is what the team decided to investigate. Lignin and manganese dioxide became the two main building blocks used to make their prototype supercapacitor.
Liang said:
Integrating biomaterials into energy storage devices has been tricky because it is difficult to control their resulting electrical properties, which then gravely affects the devices’ life cycle and performance. Also, the process of making biomaterials generally include chemical treatments that are hazardous. We have designed an environmentally friendly energy storage device that has superior electrical performance and can be manufactured easily, safely, and at a much lower cost.
In this study, we have been able to make a plant-based supercapacitor with excellent electrochemical performance using a low-cost, sustainable method. In the near future, we’d like to make our supercapacitors 100% environmentally friendly by incorporating only green, sustainable ingredients.
Upon testing their prototype green electrode, they found it stood up exceptionally well. It even maintained its ability to store an electrical charge, changing little, over thousands of charging and discharging cycles. Furthermore, it outperformed all other cutting-edge supercapacitor designs in terms of specific capacitance, which is a measure of the device’s ability to store a charge. So much so, it offered a particular capacitance that was 900 times greater than what has been reported for other supercapacitors.
Another exciting energy storage advance where researchers made a supercapacitor out of sustainable materials involves plastic waste. That team, from the University of California, Riverside, used dissolved PET plastic bottles that had been turned into microscopic fibers and then burned to transform into carbon. The final material was mixed with a binder and conducive to use in the building of the supercapacitor.
