Researchers have developed a low-cost device that can selectively capture carbon dioxide gas during charging. And when emitted, CO2 is released in a controlled manner, recovered, reused or responsibly disposed of.
A rechargeable battery-like supercapacitor device is the size of a two pence coin and is partially made of sustainable materials such as coconut shells and seawater.
Supercapacitors designed by researchers at the University of Cambridge could help power carbon capture and storage technologies at a much lower cost. Approximately 35 billion tonnes of CO2 are released into the atmosphere annually, and there is an urgent need for solutions to eliminate these emissions and address the climate crisis. State-of-the-art carbon recovery technologies now require large amounts of energy and are expensive.
A supercapacitor consists of two electrodes, a positive charge and a negative charge. In a task led by Trevor Binford while earning a master’s degree in Cambridge, the team tried to alternate between negative and positive voltages in order to extend the charging time from previous experiments. This has improved the carbon recovery capacity of supercapacitors.
Dr. Alexander Force of the Department of Chemistry, Cambridge University, Cambridge, who led the study, said:
“Our supercapacitor charge / discharge processes may use less energy than the amine heating processes currently used in the industry,” Forse said. “The next question is to investigate the exact mechanisms of CO2 capture and improve them. The next issue is scale-up.”
Results are reported in the journal Nanoscale.
Supercapacitors are similar to rechargeable batteries, but the main difference is in the way the two devices store charge. Batteries use chemical reactions to store and release charges, while supercapacitors are not dependent on chemical reactions. Instead, it relies on the movement of electrons between the electrodes, which results in slower deterioration and longer life.
“The trade-off is that supercapacitors can’t store as much charge as batteries, but when it comes to things like carbon recovery, durability is a priority,” said co-author Grace Mapstone. “The best part is that the materials used to make supercapacitors are cheap and abundant. The electrodes are made of carbon obtained from discarded coconut shells.
“We want to use materials that are inert, environmentally friendly, and infrequently discarded. For example, CO2 dissolves in water-based electrolytes, which are essentially seawater.”
However, this supercapacitor does not spontaneously absorb CO2. In other words, it needs to be charged to draw in CO2. When the electrodes are charged, the negative electrode plate draws in CO2 gas, but ignores other emissions such as oxygen, nitrogen, and water that do not contribute to climate change. Using this method, supercapacitors capture carbon and store energy.
Co-author Dr. Templano Israel contributed to the project by developing gas analysis technology for the instrument. This technique uses a pressure sensor that responds to changes in gas adsorption within the electrochemical device. The results of Temprano’s contribution help narrow down the exact mechanism that works within the supercapacitor when CO2 is absorbed and released. Before scaling up a supercapacitor, it is essential to understand all of these mechanisms, possible losses, and paths of degradation.
“This field of study is so new that we don’t yet know the exact mechanism that works inside supercapacitors,” says Temprano.
reference: Enhances supercapacity swing adsorption CO2 capture capacity by adjusting the Binford TB, Mapstone G, Temprano I, and Forse AC charging protocols. Nanoscale.. Published online May 19, 2022. doi: 10.1039 / D2NR00748G
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