While we typically work to preserve the environment, there are some aspects that cause more harm than good. Harmful algal blooms (HABs) are one of these environmentally hazardous parts of nature, severely impacting human health, the ecosystem, and the economy.
While HABs put countless people at risk though polluted drinking water, researchers are now attempting to create some good from this negative. Through heating the algal at a very high temperature in argon gas, HABs can be converted into a material known as hard carbon. Typically made from petroleum, hard carbon also has development potential through biomass. Due to the material’s qualities and capabilities, hard carbons have the potential to be used as high-capacity, low-cost electrodes for sodium-ion batteries.
“Harmful algal blooms, caused by cyanobacteria (or so called ‘blue-green algae’), severely threaten humans, livestock, and wildlife, leading to illness and sometimes even death,” says Da Deng, co-author of the recent study. “The Toledo water crisis in 2014 caused by HABs in Lake Erie is a vivid example of their powerful and destructive impact. The existing technologies to mitigate HABs are considered a ‘passive’ technology and have certain limitations. It would significantly and broadly impact our society and environment if alternative technologies could be developed to convert the HABs into functional high-value products.”
By harvesting the harmful algal and transforming it into a critical aspect for the advancement of sodium-ion batteries, the researchers are opening new doors in the field of electrochemical energy storage.
“We demonstrated the conversion of HABs, freshly collected from Lake Erie near Toledo, into high-performance electrodes for sodium-ion batteries,” says Deng. “We call it a ‘trash-to-treasure’ approach. This technology could be promising for mitigating HABs to overcome their environmental threats and providing ‘green’ electrodes for reversible sodium storage in sodium-ion batteries.”
While sodium-ion battery technology is still in its infancy, this development provides critical insight into the development of a reliable electrode material.
This from Tech Xplore:
After heating the algae, the researchers made the electrodes out of a mixture of 80% hard carbon derived from algae, 10% carbon black (to enhance conductivity) and 10% binder. After drying this slurry overnight, they assembled it into coin cells with sodium foil as the counter electrode. Tests showed that the electrodes start out with a high capacity of up to 440 mAh/g, but suffer from an irreversible capacity loss after the first cycle, bringing the capacity down to about 230 mAh/g. The electrodes then have good capacity retention from the second cycle onward. The researchers also found that some performance factors, including capacity and stability, depend on the temperature at which the algae was heated, which points to a way to improve their performance in the future.
“Our future research will focus on the optimization of electrochemical performance of HAB-derived carbon in sodium-ion batteries,” says Deng. “We will try to address the issue of first-cycle irreversible capacity loss in sodium-ion batteries. We are also interested in developing methods for the large-scale harvesting of HABs and studying their implications on the ecosystem.”
