Victoria BracamonteWith Guillermina Luque and Andrea Calderon, they received a bag of cow hair with “a frightening smell of pee.” But both they and the rest of the group Sustainable Energy Laboratory (Laes) of the National University of Cordoba (UNC) thought it could be a raw material promising to create next generation lithium batteries.
The result on the laboratory counter was a success. So it is so that Y-TEC, the YPF and CONICET companyHe decided patent development in the United States. “The next steps are to scale production and connect the tannery and battery industries to generate a circular process. This is long term,” says Victoria (38 years old), doctor in Chemistry, researcher at CONICET and professor at the Faculty of Chemical Sciences (FCQ) from UNC.
While, Ezequiel Leivaa member of Laes and researcher at CONICET and UNC, adds: “These are batteries that could become on the market only in 10 years. They are a very different technology from the current one. Development and testing on an industrial scale will take time. In any case, They will not replace current batteries either. It is likely that they coexist.”
Batteries are required for the boom electric vehicles that begins to appear. In this way, the aim is to transform the transportation sector, one of the main emitters of greenhouse gases caused by the combustion of gasoline, diesel oil and gas. The objective is to accelerate the energy transition and reduce the impact of climate change.
How a lithium battery works
Current batteries have a graphite anode and a cobalt-nickel cathode. These last ones are scarce, expensive and polluting elements. When charged, lithium ions pass to the anode. This is how energy is stored. During battery use (discharge) the lithium ions move in the opposite direction.
To achieve more efficient batteries, several limitations of this process must be resolved, such as the number of charge-discharge cycles the battery can withstand, the charging speed and its energy density. All this without compromising its safety, that is, avoiding overloads, overheating and short circuits.
Use the sulfur as cathode could generate an improvement in these qualities, in addition to being another element abundant and less polluting and expensive. In other words, a more sustainable battery would be obtained. But this sulfur needs a “skeleton” to adhere to to form the cathode. This is where the cow hair comes from.
One of the substances that is being studied to create these skeletons is biocarbons, that is, carbons obtained from the “cooking” of organic waste. Biochar has micro and nanoporous structures, which gives it a greater exposure surface. This quality can improve charging speed, energy density and provide greater stability in charging cycles.
Daniel BarracoCONICET researcher, member of Laes and UNC Secretary of Science and Technology, assures that this development was not a serendipity, a chance discovery. “We have been collaborating with Y-TEC in the development of biochars since 2017. We started with cassava starch and then became more complex with studies on peanut shells, rice and others,” he explains.
From cow hair to battery
The Laes team used cow hair to obtain biochar. But first the curious input had to undergo more domestic processes.
“We got the cow hair from an acquaintance who works in a tannery. Her first challenge was to wash her hair to get the urine out of her. There was nothing in the bibliography, so I decided to bring it home and wash it in the washing machine in a bag. Then wash it again to remove the remaining soap,” says Bracamonte.
The clean hairs were “cooked” twice until they reached 500 degrees and then 900 degrees. Then sulfur was added. This entire “recipe” is the one that is being patented by Y-TEC.
With this cathode and a pure lithium anode, a small battery like that of a watch battery was made. It achieved great electrochemical performance, very promising for these developments with sulfur. It happens that while charging a lithium-sulfur battery, chemical reactions occur that generate substances (polysulfides) that wear down the capacity.
However, in tests with cow hair biochar, these problems were not observed, at least after 100 charge-discharge cycles. “We have to study more in depth. There may be substances or something in the structure of the cow hair biochar that is preventing these unwanted substances from forming,” says Leiva. “The initial structure of the hair can have an impact on the final morphology of the biochar and be responsible for this improvement,” adds Bracamonte.
Leiva, who this year received the Konex award as one of the 100 most outstanding Argentine scientists ofe last decade, ensures that this type of batteries will provide more autonomy to future electric vehicles. “A current 200 kilo lithium battery allows a car to travel between 160 to 200 kilometers. It’s just a few kilometers. The lithium-sulfur batteries will allow ranges of up to 400 kilometers,” he explains.
The tanneries They are an important industry that uses national labor and raw materials. But it produces a large amount of solid waste and cow hair is the main one. From every ton of wet cow skin 85 kilos of residual hair are generated.
Guillermina Luque, Andrea Calderón, Fernando Cometto, Sofia Raviolo, and Melina Cozzarin also participated in the investigation. The work from which the patent was presented has already been accepted for publication in the Chemistry Select magazine and will soon be available under the title of “Sustainable Cow Hair Biocarbon-Sulfur Cathodes with Enhanced Electrochemical Performance.”
Barraco maintains: “It is a clear example that Argentine basic science can lead to important developments that can then be taken by local industries and thus grow the economy and skilled work.”
Bracamonte adds: “It was two years of hard work with the pandemic in between. We faced adverse situations regarding financing, accessibility to techniques and, at times, frustration. But we did it.”
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