Cracking into sustainable energy storage market

Chicken eggshells may be the answer to developing safer, sustainable and cost-effective rechargeable battery storage systems, according to Murdoch University research. The systems could harness eggshell proteins for electricity conduction.

Dr Manickam Minakshi Sundaram, Murdoch University Associate Professor from the Centre for Water, Energy and Waste at Harry Butler Institute, has developed a mechanism associated with electrode materials and electrolytes, offering an alternative power storage technology.

“We’ve found that chicken eggshells can be used as electrodes — a conductor of electricity — in powering batteries. Eggshells contain a high level of calcium carbonate, and when they are baked and crushed, their chemical compositions change and they become a more efficient electrode and conductor of power,” Minakshi said.

“The current lithium-ion batteries used for renewable energy storage typically use fossil fuels. Repurposing a bio-waste product like eggshells could add considerable value to the renewable energy market.

“They also offer a potentially safer option, as the current lithium battery technologies are high-cost and potentially unsafe in the event of catastrophic failure.”

The study was conducted by Minakshi as part of his higher doctorate thesis with Flinders University, focused on developing sustainable electrodes in aqueous-based energy storage technology.

According to Minakshi, the implications of this study go beyond scientific discovery. Chicken eggs and related products are used in large quantities in food processing, manufacturing and other industries, but their shells are typically sent as waste to landfill.

Eggshells and shell membranes contain a range of active chemical compounds that can be used in this development.

“The study demonstrates that highly conductive aqueous lithium and sodium electrolytes with varying salt concentrations have the potential to replace existing non-rechargeable primary batteries.

“The discovery holds the promise of high energy capacity, long cycle life and affordability in aqueous batteries,” Minakshi said.

By incorporating suitable additives such as biodegradable redox polymers, titanium boride/sulfide (TiB₂, TiS₂) or bismuth oxide (Bi₂O₃) compounds, the electrodes can be further modified to improve their performance.

Minakshi said that the research has potential applications in transitioning from a linear economy to a circular economy, helping reduce, reuse and recycle waste to improve sustainable development and address waste management.

The studies on sustainable electrode materials have also been extended to other biowaste including chitosan derived from crustaceans, mango seed husk and grape marc from wineries. From these biowastes, N-doped carbon was derived, which exhibits good electrochemical performance.

The full details of the study are available here.

Image credit: iStock.com/Jurgute