Cow hair to create more sustainable batteries

Batteries are necessary for the large-scale deployment of electric cars and other electric vehicles. In this way, the aim is to transform the transportation sector, one of the main emitters of greenhouse gases, which in this case originate after the combustion of gasoline, diesel and natural gas. The objective is to accelerate the energy transition and reduce the impact of global climate change.

Current lithium-ion batteries have a graphite anode and a cobalt-nickel cathode. The latter are scarce, expensive and polluting elements. When charged, lithium ions move 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 that the battery is able to withstand, the charging speed and its energy density. All this without compromising your security; that is, avoid overloads, overheating and short circuits.

Using sulfur as a cathode could generate an improvement in these qualities. In addition, it is a more abundant, less polluting and less expensive chemical element. That is, a more sustainable battery would be obtained. But this sulfur needs a “skeleton” to adhere to to form the cathode. Here comes an undoubtedly striking, although ecological and sustainable, component that scientists have identified as suitable for this project: cow hair.

The team in question is made up of scientists from the National University of Córdoba (UNC) in Argentina.

The final phase of the research work began in a somewhat unusual and unpleasant way. Victoria Bracamonte, along with Guillermina Luque and Andrea Calderón, received a bag of cow hair with “a frightening smell of pee.” But both they and the rest of the group at the UNC Sustainable Energy Laboratory (LAES) knew that it could be an ideal raw material to create next-generation lithium batteries.

The result was a success. So much so that a patent has been filed in the United States.

Members of the research team. (Photo: UNCiencia / UNC)

“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 Bracamonte, who is a chemist, researcher at the National Scientific and Technical Research Council (CONICET) in Argentina and professor at the Faculty of Chemical Sciences (FCQ) of the UNC.

Meanwhile, Ezequiel Leiva, member of LAES and researcher at CONICET and UNC, adds: “These are batteries that could be on the market within 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.”

One of the substances being studied to create these skeletons are biochars: 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.

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 I washed 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.

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 reduce 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 of the past decade, assures 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.

Tanneries are an industry that produces a large amount of solid waste and cow hair is the main one. From each ton of wet cow skin, 85 kilos of residual hair are generated. In Argentina, this industrial sector has a fairly large size.

Guillermina Luque, Andrea Calderón, Fernando Cometto, Sofia Raviolo and Melina Cozzarin also participated in the investigation. The study, from which a patent was filed, has already been accepted for publication in the academic journal Chemistry Select and will soon appear there under the title “Sustainable Cow Hair Biocarbon-Sulfur Cathodes with Enhanced Electrochemical Performance.” (Source: Lucas Viano / UNCiencia / UNC / Argentina Investiga)