Chinese researchers use seaweed to power devices

Seaweed might no longer just be found on your sushi platter, as Chinese researchers discover a way for the algae to give a power boost to our devices.

A team of scientists from Qingdao University have developed a seaweed-derived material that can be used to enhance the performance of semiconductors, lithium-ion batteries and fuel cells.

Carbon-based materials are currently used for energy storage and energy conversion, such as graphite. However, the researchers wanted to create a more sustainable way to keep up with the rapidly growing demand for bigger storage devices, and turned for help to earth-abundant seaweed that grows readily in salt water.

"We wanted to produce carbon-based materials via a really 'green' pathway,” said Dongjiang Yang, a nanotechnology expert at the university and lead author of the study. “Given the renewability of seaweed, we chose seaweed extract to synthesise porous carbon materials."

The team created the porous carbon nanofibres by binding metal ions such as cobalt to the molecules from the seaweed extract – a process called ‘chelating’. This resulted in the nanofibres forming an “egg-box” structure, where the seaweed extract engulfs the metal ions, creating a stable material.

Testing the seaweed-derived material showed that it is significantly better than conventional graphite anodes for lithium-ion batteries, said the scientists.

The research could lead to longer ranges on a single charge for electric cars and even higher capacitance in zinc-air batteries if used as a superconductor material.

The nanofibres also showed improved stability as catalysts for fuel cells, compared to traditional platinum-based catalysts, say the researchers.

The team is now developing seaweed-derived cathodes for lithium-ion batteries and working on suppressing defects that materialise in these cathodes that reduce the mobility of lithium ions and deteriorate the batteries. The scientists are also branching out on the natural materials they use by developing a material using red algae and iron with a high surface area for lithium-sulphur batteries and supercapacitors.

However, the material might not be commercialised for use in batteries anytime soon. As of now, only 18,000 tonnes of seaweed extract can be obtained annually for industrial use and a lot more will be required to produce the material on a commercial scale.