Researchers at Queensland University of Technology have developed electrodes for batteries that can be recharged at a much faster rate. The inspiration for the research is a water-carrying membrane that is found inside of bamboo – the fastest growing plant in the world.
Professor Ziqi Sun was first inspired for the study when he walked past a clump of bamboo in the Brisbane City Botanic Gardens. His work is focused on mimicking natural objects, such as seashells and fish scales, to develop sustainable energy solutions.
According to Professor Sun, the new study was focused on the multilayer membrane that runs up inside the bamboo stem. This membrane, which is about as thick as a piece of paper, is responsible for the ultrafast transport of water and nutrients.
Thanks to this tissue, bamboo can grow up to an estimated rate of about 40 millimeters per hour.
Professor Sun said the membrane was made up of layers, with the layers packed very closely together on the side closest to the inner ring of the bamboo, and further apart on the side nearest the center of the bamboo. The layers also have a porous structure on the surface.
“Why does the bamboo have this membrane? It’s not just something for decoration, it must be for some specific function,” explained Professor Sun.
Study first author Dr. Jun Mei said the unique structure and its function deserved an in-depth study.
“The membrane is the most important component in the energy storage devices, and it would be very exciting if we could find a potential material candidate for energy storages by learning from the relationship between the membrane structure and the specific function,” explained Dr. Mei.
The researchers found that this multilevel structure enables water and electrolytes to travel through the bamboo in two ways.
The inner layer enables the “superfluidic” travel of the liquid and electrolytes, which means the liquid travels very quickly through the plant. The outer layer allows the liquid to be more quickly dispersed throughout the structure.
The research expands upon previous work that demonstrates the benefits of two-dimensional nanomaterials for the ultrafast transport of ions through a battery.
“Nature has taught us how to design with these kinds of two-dimensional materials, and how a multilevel distribution of the space will be much more helpful for high-performance batteries,” said Professor Sun.
The researchers developed their own membrane using layers of nanosheets of cobalt oxides and graphene. Each individual sheet was about 100,000 times thinner than a human hair.
Ultimately, the bioinspired membranes showed a superwetting behavior towards organic electrolyte. This means there was no barrier for the contact and entry of the electrolyte from the surface into the inside membrane.
“The study offers a new principle in designing high-performance energy materials,”said Professor Sun. “Most importantly, it paves a way for future materials intervention by learning from the greatness of nature.”
The study is published in the journal Advanced Functional Materials.