Seaweed nanomaterials boost sodium battery performance

Nanomaterials made from seaweed could pave the way for a greener and more efficient type of energy storage, researchers have said.

The team, led by the University of Bristol, used cellulose nanomaterials derived from brown seaweed to make a separator for sodium metal batteries (SMBs), which could offer a sustainable alternative to lithium ion.

SMBs are one of the most promising high-energy and low-cost energy storage systems for the next generation of large-scale applications, the Bristol team claimed. One of the major obstacles to their development is the uncontrolled growth of dendrites however, which can penetrate a battery’s separator and result in short circuits.

The new research, which builds on previous work at the University of Bristol in collaboration with Imperial College and University College London, describes how fibres containing the seaweed derived nanomaterials not only stop crystals from the sodium electrodes penetrating the separator, but also improve the performance of the batteries.

“The aim of a separator is to separate the functioning parts of a battery (the plus and the minus ends) and allow free transport of the charge,” said Jing Wang, first author and PhD student in the Bristol Composites Institute (BCI).

“We have shown that seaweed-based materials can make the separator very strong and prevent it being punctured by metal structures made from sodium. It also allows for greater storage capacity and efficiency, increasing the lifetime of the batteries – something which is key to powering devices such as mobile phones for much longer.”

Co-author Dr Amaka Onyianta, also from the BCI and creator of the cellulose nanomaterials, said: “I was delighted to see that these nanomaterials are able to strengthen the separator materials and enhance our capability to move towards sodium-based batteries. This means we wouldn’t have to rely on scarce materials such as lithium, which is often mined unethically and uses a great deal of natural resources, such as water, to extract it.”

Research leader Professor Steve Eichhorn, from the BCI, said: “This work really demonstrates that greener forms of energy storage are possible, without being destructive to the environment in their production.”

The next challenge is to upscale production of the materials, the researchers said.

The work was published in Advanced Materials.