A green battery separator solution made from seaweed paves the way for greener energy storage.

A team at the University of Bristol, UK, in collaboration with Imperial College and University College London, has succeeded in making a separator from cellulose nanomaterials derived from brown seaweed.

The University’s research describes how fibres containing seaweed-derived nanomaterials stop crystals from sodium electrodes penetrating the separator. They also found that they improve the performance of the batteries.

This could have huge implications for traditional battery materials such as lithium, which is a scarce resource, as well as often being mined unethically and using a great deal of natural resources, such as water, to extract it.

One of the major impediments to the development of sodium-metal batteries is uncontrolled dendrite growth, which penetrate the battery’s separator and result in short-circuiting.

“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. 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,” said Jing Wang, first author and PhD student in the Bristol Composites Institute (BCI).

“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 work really demonstrates that greener forms of energy storage are possible, without being destructive to the environment in their production,” said Professor Steve Eichhorn who led the research at the Bristol Composites Institute.

The next challenge is to upscale production of these materials and to supplant current lithium-based technology.