High-performance sodium and potassium ion batteries via new carbon electrode materials

Sodium-ion and potassium-ion batteries are prospective lithium-free alternatives for large-scale energy storage systems based on abundant, more environmentally friendly resources. However, unsatisfactory rate and cycling performance due to the larger sizes of sodium and potassium ions and their ability to move through the porous carbon-based anodes has held back the application of these battery technologies.

Now a group of researchers from the Bristol Composites Institute and Imperial College has developed high-performance sodium and potassium ion batteries using sustainably sourced cellulose. They implemented a novel controllable unidirectional ice-templating strategy to develop new carbon electrode materials, called aerogels. In aerogels, cellulose nanocrystals are formed into a porous structure using ice crystals that are grown and then sublimated, thereby leaving large channels within the structure that can carry the large sodium and potassium ions.

“We proposed a novel controllable ice-templating strategy to fabricate low-cost cellulose nanocrystals/polyethylene oxide-derived carbon aerogels with hierarchically tailored and vertically-aligned channels as electrode materials, which can be utilized to well-tuning the rate capability and cycling stability of sodium- and potassium-ion batteries,” said Jing Wang, lead author and a PhD student in the Bristol Composites Institute.

The researchers were astounded with the performances of these new batteries, which are presented in detail in the paper “Ice-Templated, Sustainable Carbon Aerogels with Hierarchically Tailored Channels for Sodium- and Potassium-Ion Batteries,” published in Advanced Functional Materials.

Their results demonstrate a practical pathway to tune electrochemical storage performance through a controllable ice-templating strategy which, according to the researchers, can be easily extended to a variety of other energy storage systems such as zinc-, calcium-, aluminum-, and magnesium-ion batteries, exhibiting its universal potential for the next-generation of energy storage systems.

“Benefiting from the renewability of the precursor and scalability at relatively low cost in the environmentally benign synthesis process, this work could offer an appealing route to promote large-scale applications of sustainable electric vehicles and large-scale energy storage grids in the near future,” she added.

In the light of these findings, the researchers hope to collaborate with industries to develop this strategy on an industrial scale and further explore the potential of this technology across a broad range of battery storage systems.