Scientists led by Nanyang Technological University, Singapore (NTU Singapore) have developed a novel method of using fruit peel waste to extract and reuse precious metals from spent lithium-ion batteries to create new batteries, which was published in Environmental Science & Technology on July 9, 2020.The team has demonstrated an effective ecofriendly, and sustainable strategy to minimize the environmental footprint of both waste type their concept using orange peel, which recovered precious metals from battery waste efficiently. Further, they have made functional batteries from these recovered metals, creating minimal waste in this process.
Fruit peel to turn old into new batteries. Credit to Dr. ASG
This considerable approach is to be relatively more eco-friendly than conventional methods, the use of such strong chemicals on an industrial scale could generate a substantial amount of secondary pollutants, posing significant safety and health risks. Therefore, Scientific News Blog (SNB) team has interested in “Re-purposing of fruit peel waste as a green reductant for recycling of spent lithium ion batteries” published by Prof. C. Y. Tay & his team from NTU, Singapore. We would like to congratulate them on their new innovative technology.
The scientists have identified the new ideology, that their waste-to-resource approach tackles from food waste and electronics waste, supporting the development of a circular economy with zero waste, in which resources are kept in use for as long as possible. An estimated 1.3 billion tonnes of food waste and 50 million tonnes of e-waste are generated globally each year.
Spent
batteries are conventionally treated with extreme heat (over 500°C) to smelt
valuable metals, which emits hazardous toxic gases. Alternative approaches that
use strong acids solutions or weaker acid solutions with hydrogen
peroxide to extract the metals are being explored, but still they have to produce secondary pollutants
that pose health and safety risks, or relies on hydrogen peroxide which is
hazardous and unstable.
Current industrial recycling processes of e-waste are energy-intensive and emit harmful pollutants and liquid waste, pointing to an urgent need for eco-friendly methods as the amount of e-waste grows. Their team has been demonstrated that it is possible to do so with existing biodegradable substances.
“These findings build on our existing body of work at SCARCE under NTU’s Energy Research Institute (ERI@N). The SCARCE lab was set up to develop greener ways of recycling e-waste. It is also part of the NTU Smart Campus initiative, which aims to develop technologically advanced solutions for a sustainable future”.
---- Chor Yong Tay, Professor, NTU, Singapore
In Singapore, a resource-scarce country, this process of urban mining to extract valuable metals from all kinds of discarded electronics becomes very important. By this method, not alone the problem of resource depletion by keeping these precious metals have been tackled in use as much as possible, but also the problem of e-waste and food waste accumulation – both a growing global crisis.
Low cost and remarkable for the sustainable developmental goals in to industries: With the industrial approaches to recycling battery waste generating harmful pollutants, hydro-metallurgy – using water as a solvent for extraction – is increasingly being explored as a possible alternative. This process involves first shredding and crushing used batteries to form a crushed material called black mass. Researchers then extract valuable metals from the black mass by dissolving it in a mix of strong acids or weak acids plus other chemicals like hydrogen peroxide under heat, before letting the metals precipitate.
The NTU team have found that the combination of orange peel that has been oven-dried and ground into powder, and citric acid, a weak organic acid found in citrus fruits, can achieve the same goal.
From the lab experiments, the team has found that their approach was successfully extracted to around 90% of cobalt, lithium, nickel, and manganese from spend lithium-ion batteries – a comparable efficacy of this approach using hydrogen peroxide.
“The key lies in the cellulose found in orange peel, which is converted into sugars under heat during the extraction process. The specific sugars will enhance the recovery of metals from battery waste. Naturally-occurring antioxidants found in orange peel, such as flavonoids and phenolic acids, could have been contributed to this enhancement as well”.
Figure 1. Mechanistic and process summary of OP-enabled recycling of spent LIBs [1].
Importantly, solid residues generated from this process were found to be non-toxic, suggesting that this method is environmentally sound, they have added.
From the recovered materials, it is then assembled with new lithium-ion batteries, which showed a similar charge capacity to commercial ones. Further research is underway to optimize the charge-discharge cycling performance of these new batteries made from recovered materials.
The researchers have suggested that this new technology is practically feasible for recycling spent lithium ion batteries in the industrial sense.
Future perspectives: The team is now looking to further improve the performance of their batteries generated from treated battery waste. They are also optimizing the conditions to scale up production and exploring the possibility of removing the use of acids in the process.
This waste-to-resource approach could also potentially be extended to other types of cellulose-rich fruit and vegetable waste, as well as lithium-ion battery types such as lithium iron phosphate and lithium nickel manganese cobalt oxide. This would help to make great strides towards the new circular economy of e-waste, and power our lives in a greener and more sustainable manner.
Reference
[1]. Z. Wu, T. Soh, J. J. Chan, S. Meng, D. Meyer, M. Srinivasan, C. Y. Tay, Environ. Sci. Technol. 54(15), 9681–9692 (2020).
Blog Written By
Dr. Y. SASIKUMAR
School of Materials Science & Engineering,
Tianjin University of Technology,
Tianjin 300384, China
Editors
Dr. A. S. Ganeshraja
Dr. S. Chandrasekar
Dr. K. Rajkumar
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