Murdoch University research finds new use for eggshells

Associate professor Dr Manickam Minakshi Sundaram has developed a new way for eggshells to be used to conduct electricity in lithium-ion batteries, offering an alternative to current expensive and unethical materials.

Dr Minakshi said the team had been working with various sustainable materials including grape marc, rock melon skin and mango seed husk, but had found egg shells suitable because they did not need be converted into anything else.

"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," he said.

Dr Minakshi said they took the shells, often a throwaway product going into landfill, washed and dried them before crushing.

"We put that on one of our carbon electrodes as a substrate in the electrolyte, and then it was doing a good job in terms of absorbing the ions from the electrolyte then releasing it," he said.

"This was very similar to one of the electrodes that's been used in any of the batteries for storing and releasing the energy."

Dr Minakshi said current lithium-ion batteries used for renewable energy storage typically used fossil fuels.

"Repurposing a bio-waste product like eggshells could add considerable value to the renewable energy market," he said.

Dr Minakshi said the materials currently used for conductors in batteries were either toxic, have an expensive supply chain, or have other issues involved in their mining.

"Particularly the material like cobalt that we are using in our laptop computers, and mobile phones, they are coming from a region like Congo, so there is a lot of child labour has been involved and it's not very ethical," he said.

"But with egg shells it's not like that - we are not using any sort of either expensive material or unethical material. What are the other way around - we are just re purposing what is ending up in the landfill.

"So if we can convert this to a useful product, like using one of the electrodes, we could transition from a linear economy to a circular economy, reducing, reusing and recycling waste improving both sustainable development and addressing waste management."

Dr Minakshi said further research would be conducted to expand the research and take it to an industrial scale in the future.