90% metal recovery: Singapore pilot plant uses orange, lemon, pineapple peels to recycle batteries

A pilot recycling plant in Singapore is testing an unusual but potentially greener way to recover valuable metals from spent lithium-ion batteries: using discarded orange, lemon, and pineapple peels.

Researchers from Nanyang Technological University (NTU), working with local battery recycling company Se-cure Waste Management, have scaled up a technology that was first demonstrated in the laboratory in 2020.

The pilot facility, located at Neythal Road near Pioneer Road North, has been operational since late 2022 and can process up to 2,000 litres of shredded battery waste at a time, according to an official report by NTU Singapore.

The technology addresses two growing waste problems simultaneously: electronic waste and discarded food. Globally, less than 5% of spent lithium-ion batteries are recycled, while the amount of used batteries is projected to reach 11 million tonnes by 2030.

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The process begins by shredding and crushing used batteries. Plastics and metals such as copper, aluminium, and iron are separated, leaving behind a material known as black mass, which contains valuable electrode metals including cobalt, lithium, nickel, and manganese. The black mass is then treated with solvents derived from fruit-peel waste.

NTU researchers call the approach “hydro-organic-metallurgy.” Fruit peels contain sugars, organic acids, flavonoids and phenolic acids that help dissolve and recover metals from battery waste. The recovered materials are subsequently converted into metal salts that can potentially be used to manufacture new lithium-ion batteries.

In laboratory experiments conducted in 2020, the NTU team recovered more than 90% by weight of valuable metals from processed battery waste using orange peel. Batteries produced from the recovered metals demonstrated a charge capacity similar to commercial batteries. The researchers later replicated the process using lemon and pineapple peels, among other biomass sources.

Associate Professor Dalton Tay said the technology could provide a scalable way to tackle both waste streams.

“The proposed innovation provides an immediate and scalable solution to reduce both food waste and electronic waste.”

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Tay also described the recovered materials as a way to create a circular system. "The recovered metal salts can then be reused to generate new batteries, and by doing so, we're able to close the waste loop while offering a sustainable cradle-to-cradle solution."

The pilot project is now focused on improving metal-recovery yields while assessing its technical performance and economic viability. If successful, the fruit-peel-based method could offer a less hazardous alternative to conventional recycling processes that rely on strongly corrosive chemicals or high temperatures