Researchers from the University of Bristol have unveiled a new strategy for sustainable post-lithium-ion batteries, an advance believed to have far-reaching implications for e-vehicles and electronic devices.
The team is said to have developed high-quality sodium and potassium ion batteries using sustainably sourced cellulose.
In a paper published in Advanced functional materials, university scientists Bristol Composites Institute Describe a novel controllable unidirectional ice templating strategy that can adjust the electrochemical performance of next-generation post-lithium-ion batteries with durability and large-scale availability.
Currently, electric vehicles and portable devices such as cell phones rely largely on lithium-ion batteries. Batteries have two electrodes and a separator, with an electrolyte in between that carries the charge. Problems with using lithium for these batteries include the build-up of metal in the devices, which can lead to short circuits and overheating.
Alternatives such as sodium and potassium batteries have not performed as well in the past in terms of speed performance and ability to withstand repeated use. This is due to the larger size of sodium and potassium ions and their ability to move through the porous carbon electrodes of the batteries.
Nor can they be easily thrown away at the end of their useful life, materials can be costly and lithium mining in countries such as Chile, Bolivia and Argentina has a poor human rights record.
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The work of the Bristol Composites Institute, in collaboration with Imperial College, includes the development of new carbon electrode materials based on the new ice template system.
These materials are called aerogels, where nanocrystals of cellulose are formed into a porous structure using ice crystals that are grown and then sublimated. This leaves large channels in the structure that can carry the large sodium and potassium ions.
Co-author Steve Eichhorn, a professor of materials science and engineering at the University of Bristol and an expert in cellulose-based technologies, said the team was “stunned” at the performance of the new batteries.
He added that the team now hopes to work with industry to explore extending the technology to a variety of other energy storage systems, such as zinc, calcium, aluminum and magnesium-ion batteries.
Jing Wang, lead author and a PhD student at the Bristol Composites Institute said: “Taking advantage of the precursor’s renewability and relatively low-cost scalability in the eco-friendly synthesis process, this work could provide an attractive route to promote large-scale applications of sustainable electric vehicles and large-scale energy storage networks in the near future.”