Trees For Energy Storage: Cellulose From Trees Can Be Used To Build High-Energy Capacitators
They provide food and oxygen, clean the air, reduce greenhouse effect, conserve energy, cool the streets, and now according to new research, trees may very soon help in building sophisticated storage devices. This discovery was made by scientists at Oregon State University when they found that cellulose, found in trees, undergoes a chemical reaction, which can have great potential as supercapacitators. Their study was published in Nano Letters, a journal of the American Chemical Society.
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Cellulose is the organic compound, which helps trees stand up straight and strong. It is the most abundant polymer on Earth and has myriad uses. In the new experiment, when scientists heated cellulose in a furnace in the presence of ammonia, it turned to nitrogen-doped, nanoporous carbon membranes, the building blocks needed to make supercapacitators.
Supercapacitators have wide industrial applications and are used in trains, planes, and automobiles. But until now, the cost of mass-production of good quality devices was very high, which curtailed their wide-spread use.
This new method developed by the OSU scientists is cheap, quick, and environment friendly. The carbon membranes in the cellulose are extremely thin, with a single gram having a surface area of nearly 2,000 square meters. The exposure to high heat and ammonia converts the cellulose to a nanoporous carbon material used in supercapacitors. It is a cheap, single-step process and the only byproduct is methane, which can be used as fuel.
"The ease, speed and potential of this process is really exciting," said lead author Xiulei (David) Ji, an assistant professor of chemistry in the OSU College of Science.
"For the first time we've proven that you can react cellulose with ammonia and create these N-doped nanoporous carbon membranes," Ji said. "It's surprising that such a basic reaction was not reported before. Not only are there industrial applications, but this opens a whole new scientific area, studying reducing gas agents for carbon activation. We're going to take cheap wood and turn it into a valuable high-tech product."
Supercapacitators are high power energy devices and are used in applications where a large amount of power is needed for a relatively short time. They are more powerful than batteries and can be recharged faster, and require less complicated charging circuits.
They are used in computers and consumer electronics such as digital camera flashes and even electric cars. In heavy industries, they are used in cranes, trains, power and braking recuperation systems, truck lifts, and track switching. They also have applications in wind-generated power production.
Besides supercapacitors, nanoporous carbon materials also have applications in adsorbing gas pollutants, environmental filters, water treatment and other uses.
"There are many applications of supercapacitors around the world, but right now the field is constrained by cost. If we use this very fast, simple process to make these devices much less expensive, there could be huge benefits", said Ji.
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