Transcript
In a new study, published the journal Energy Storage, researchers at Texas A&M University describe a novel plant-based energy storage device that could soon be charging everything from computers and phones to electric cars within just a few minutes. Furthermore, these devices are flexible, lightweight, and cost-effective.
Integrating biomaterials into energy storage devices has been tricky because it is difficult to control their resulting electrical properties, which determines the devices' life cycle and performance. Furthermore, the process of making biomaterials generally include chemical treatments that are hazardous. But now, the Texas A&M researchers have designed an environmentally friendly energy storage device that has superior electrical performance and can be manufactured easily, safely, and at a very low cost.
Energy storage devices take two common forms: batteries or supercapacitors. Although both types of devices can deliver electrical currents when required, they have fundamental differences. While batteries can store large amounts of charge per unit volume, supercapacitors are much more efficient at generating a large quantity of electric current within a short duration. This burst of electricity helps supercapacitors to quickly charge up devices, while batteries take much longer.
Supercapacitors have an internal architecture that is somewhat like basic capacitors. Both of these devices store charge on metal plates or electrodes. However, unlike basic capacitors, supercapacitors can be made in different sizes, shapes, and designs, depending on the intended application. Furthermore, supercapacitor electrodes can also be built with different materials.
For their work, the researchers selected manganese dioxide nanoparticles for designing one of the two supercapacitor electrodes. Manganese dioxide is cheap, available in abundance, and is safe compared to other transition metal oxides, like ruthenium or zinc oxide, which are popularly used for making electrodes.
Past research has shown that lignin, a natural polymer that glues wood fibers together, used with metal oxides enhances the electrochemical properties of electrodes. However, there have been few studies looking into combining manganese dioxide and lignin to leverage both of their useful properties.
The researchers assembled their supercapacitor by sandwiching a gel electrolyte between one electrode made of lignin, manganese dioxide, and aluminum and another electrode made of aluminum and activated charcoal.
Upon testing it, they found that their supercapacitor had very stable electrochemical properties. In particular, the ability of the device to store an electrical charge, changed little, after thousands of cycles of charging and discharging. Also, for an optimal lignin-manganese dioxide ratio, the specific capacitance was observed to be up to 900 times greater than what has been reported for other supercapacitors.
Furthermore, these supercapacitors are also very light and flexible, which would enhance their usefulness as structural energy storage elements in vehicles and robots.
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