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The scientists of Sustainable Energy Laboratory (LaES) from the National University of Córdoba (UNC) have been working with organic waste such as malt, peanut shells or rice to produce biochars for eight years. Now, the team of 30 people, including researchers Victoria Bracamonte, Guillermina Luque, Andrea Calderón, Daniel Barraco and Ezequiel Leiva, wants to convert a raw material abundant in a livestock country like Argentina, cow hair, into energy. of the future through the creation of next-generation lithium-sulfur batteries.
Before the pandemic, scientists began experimenting with cow hair and discovered that it could be a promising raw material. “We received hair from a tannery that smelled like cow pee, Vicky [Bracamonte] She washed her hair for the first time in the washing machine at home, then dried it in the oven in her kitchen. We washed it again with isopropyl alcohol in the laboratory and began the process to obtain the biochar,” details Guillermina Luque, in relation to the beginnings.
Lithium-sulfur batteries are the promise of the energy transition, on the path to mitigating climate change, especially in the automotive market since combustion vehicles are large emitters of greenhouse gases. But although tests are being carried out with them in laboratories around the world, they are not yet commercialized.
“This would be a new generation of batteries that is not yet on the market today. Cow hair is a material that no one had used for this purpose until now,” explains Ezequiel Leiva, who this year received the Konex award as one of the 100 most outstanding Argentine scientists in the last decade.
The work is funded by YPF Technology (Y-Tec)the most important research and development company for the energy industry in Argentina, and the National Council for Scientific and Technical Research (Conicet)with the support of other State institutions.
Leiva believes that development on an industrial scale will take about ten years and that lithium-sulfur plants will coexist with current lithium-ion plants to supply the automotive industry against the boom of electric cars. According to an analysis of PwC and Strategy&battery electric vehicles (BEVs) accounted for 14.3% of new car registrations in 14 major markets in 2022, up from just 4.1% in 2020 and 8.2% in 2021. Additionally, predicts that in 2026 the price of electric vehicles will be equal to that of combustion vehicles in the most developed countries, indicates a report from Statista. In other words, a large increase in the demand for batteries is expected. In Norway, 60% of vehicles sold in 2021 were electric. In China, six million will be registered in 2022. “In this decade and the next there will be a revolution in terms of this technology,” says Leiva.
Ramiro Pereyra
The value of a waste
The Argentine development, patented in the United States and published in the magazine Chemistry Select, It has at least two notable aspects, according to LaES scientists and independent experts.
On the one hand, the commitment to the circular economy is valued. The novelty is the raw material, an industrial waste that this livestock country produces in large quantities. Cow hair is the main solid waste from tanneries, which is thrown away or used to fill floors. It is estimated that For every ton of wet cow skin, 85 kilos of residual hair are generated. that yield eight kilos of charcoal. In the year 2020 77,000 tons of cowhide were produced, which could produce 616,000 kilos of carbon material for the cathode. “It is interesting to give added value to something that is useless and that can be used in a battery to store energy,” thinks Luque.
On the other hand, biochar obtained from cow hair presents a reduction in the chemical reactions that generate polysulfides that wear down the capacity of batteries. The structure achieved after processing this organic waste would prevent these unwanted substances from forming. “One of the benefits of cow hair is that it is capable of retaining polysulfides, those soluble sulfur species, which prevents the loss of material from that battery,” details Leiva.
The independent scientific community also considers this development to have enormous potential. Arnaldo Visintin, professor at the National University of La Plata (UNLP) and senior researcher at Conicet, says that it is “a very important contribution.” He also believes that this laboratory work could be carried out in the not too distant future in UniLiBthe first Argentine pilot factory of national cells for lithium ion batteries – a joint venture between Y-Tec and UNLP – in the Buenos Aires town of Berisso.
“I think that in less than ten years a lithium-sulfur prototype can be carried out,” says Visintin. “The lithium-sulfur battery is the battery of the future, but it still has some problems that this method devised in Córdoba greatly improves, since it reaches up to one hundred charge and discharge cycles and one thousand cycles with 50% discharge; very good capacity. That is new, it is an important contribution,” says the researcher.
![Bovine hair is the main solid waste from tanneries; scientists use the organic waste to develop a prototype of lithium-sulfur batteries.](https://imagenes.elpais.com/resizer/iDaWKvXkhXOeHHXYqbUw054vOeE=/414x0/cloudfront-eu-central-1.images.arcpublishing.com/prisa/LJL472X37VGWPM6ZS6E27QCVMA.jpg)
Ramiro Pereyra
What is it about
Current batteries have two electrodes: a graphite anode and a cobalt and nickel cathode, expensive and polluting metals. Leiva explains that they are looking to replace that cathode with one that has sulfur. The lithium-sulfur ones, in addition to being more economical and ecological, would have greater autonomy, charging speed and energy density. They would be more sustainable.
The process to produce biochars from cow hair is carried out entirely in the laboratory. The raw material is subjected to a kind of “cooking” in two stages. The synthesized biochar is washed and mixed with sulfur, obtaining a composite material that is used to manufacture the electrodes. Once these cathodes are prepared, they are tested in “button” type cells, which use lithium as a counter electrode. This biochar-sulfur composite has specific qualities hitherto not observed in other materials used by researchers. Its micro and nanoporous structure is what enables a good response from the battery.
“What's so special about cow hair? A structure that when attacked generates meso and micropores that can retain sulfur. It has that uniqueness; “Not all materials give the same response,” says Leiva. Sulfur is a non-conductive material that has to be covered by a carbonaceous material that gives it, precisely, conductivity. In this case, what was observed is that the battery can store a large amount of lithium, with many charge and discharge cycles.
![Ezequiel Leiva, Victoria Bracamonte, Guillermina Luque and Andrea Calderón scientists from the Sustainable Energy Laboratory (LaES) of the National University of Córdoba (UNC) who developed the project.](https://imagenes.elpais.com/resizer/PpAf68cFvc5vhiyWGZyCTYoR3U0=/414x0/cloudfront-eu-central-1.images.arcpublishing.com/prisa/ICMA2NP5TFBWVKTACPIBOKSCSI.jpg)
Leiva assures that batteries of this type will allow future electric vehicles to double their autonomy. “If we take it to an electric car, the lithium-ion batteries have reached their maximum possible capacity, a range of approximately 300 kilometers. The lithium-sulfur battery would allow the car to travel 600 kilometers, similar to that of internal combustion,” Luque agrees. He suggests that we could also think about using this type of energy for larger vehicles, even airplanes.
Bracamonte emphasizes that the work carried out by the team highlights the contribution that science and technology can make to the development of a country. Not only favoring the internal population, but in this case positioning Argentina as a producer of raw materials for energy.
Although there is still a long process ahead, including improvements in battery speed and optimizing the procedure, Leiva thinks cow hair is a good candidate. “There is work to do. The interesting thing is that this rather premature stage shows that this compound is viable,” she emphasizes.
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