As the cost of lithium-ion batteries continues to fall, they are rapidly replacing the lead-acid batteries that were formerly used in automobiles and other vehicles. This is causing an overabundance of spent lead-acid batteries, which are hazardous to the environment and individuals if not properly recycled. To address this issue, researchers devised an ecologically acceptable process for converting lead from spent lead-acid batteries into UV-visible photodetectors.
“We think that this recycling technique might greatly decrease lead contamination from discarded lead-acid batteries, which is crucial for the environment,” said Longxing Su of China’s Southern University of Science and Technology. “By generating a market for used lead, the photodetectors boost the recycling economy. They have several uses, including optical communication, chemical analysis, and imaging.”
Su and colleagues discuss their method for extracting lead from spent lead-acid batteries and then utilising it to synthesis lead(II)iodide (PbI2) microcrystals suitable for use in photodetectors in the journal Optics Letters.
“The recovered PbI2 microcrystals have the quality and purity standards required for photodetectors,” Su stated. “We also demonstrate that the microcrystals may be utilised to fabricate photodetectors with high stability, repeatability, and response speeds.”
A fresh application for obsolete batteries
Although lead contained in discarded lead-acid batteries may be recycled, most techniques are costly and have a number of downsides. Su’s team devised a more efficient method for producing PbI2 from lead paste present in lead-acid batteries.
The researchers created a one-pot procedure to extract the lead from the paste that uses just cheap, readily obtainable chemicals and no commercial precursors, which would raise the cost. The paste is placed in a solution containing excess citric acid monohydrate, sodium citrate dihydrate, and H2O2. Because of the extra sodium citrate dihydrate, practically all of the produced lead citrate dissolves in the combined solution. The combination is subsequently filtered to yield a clear lead-containing solution. When too much hydroiodic acid is added to the solution, it precipitates yellow PbI2, which is collected and dried in a vacuum.
The PbI2 created by this approach was then utilised to make a photodetector using a simple spin-coating procedure. They examined the photodetector’s photo response utilising a UV-Visible light source of 300 W Xe-lamp and an electric signal collector of a semiconductor parameter instrument. Under 10 V bias voltage, the PbI2 photodetector they built had a low dark current of 1.06 nA and an on-off ratio of 103.
Following steps
The researchers are currently attempting to scale up their technique in order to mass-produce regenerated PbI2. Prior to commercialisation, independent testing organisations and firms interested in integrating the photodetectors into downstream goods would need to verify the recycled PbI2 and photodetectors created from it.
“We hope that our study will be recognised by chemical businesses and downstream industries so that our technology may be commercialised,” Su added. “Our green reactant recycling technology might be beneficial in other applications, such as the production of solar cells.”
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