The automotive industry has launched itself into electrification arms. Be with the hybrids, plug-ins either 100% electricthey all have batteries, and the key to convincing more users of make the jump from your combustion car is guarantee greater autonomy. The solid state batteries are one of the technologies in researchbut there are other very promising ones such as lithium-sulfur, and the University of Córdoba believes that there are two secret ingredients to improve the formula.
Urine and excrement.
Li-S. They are not new. We have been talking about the lithium sulfide batteriesand while we find the economy of scale necessary for solid-state ones to establish themselves, lithium-sulfur ones are one of the hopes for electric cars. They have twice the real energy density of lithium-ion, sulfur is extremely abundant and economical compared to critical materials such as cobalt or nickel, It is not something that China controlsit is safer because the risk of thermal runaway is lower and the environmental impact is reduced.
They are not perfect, since the conductivity is low, the manufacturing processes are not as optimized as those of current alternatives and, above all, the current useful life is very limited: although they are moving forward In this sense, just 300-500 charge cycles compared to between 1,000 and 3,000 for lithium-ion batteries. However, as we say, they have become a promising technology, and the University of Córdoba wants one of the ingredients in the battery to be… poop.
Batteries from waste. The Chemical Institute for Energy and the Environment, or IQUEMA, of the University of Córdoba has published a study in which they test the potential of sludge from a municipal treatment plant when converting it into activated carbon. It is an essential material for lithium-sulfur batteries, since it works as a conductor, and they consider it to be the answer to the challenge of optimizing the electrodes of these batteries.
As we said, sulfur has advantages, but one of the great deficiencies is its conductivity index. This requires active carbon and other conductive matrices that are expensive to produce. But of course, if this conductive matrix is created from waste that all cities in the world produce no matter what, things change.
Villaviciosa de Córdoba. To do this, IQUEMA has used sludge from the wastewater station of Villaviciosa de Córdoba. This plant uses a treatment system that generates a sludge with an interesting composition to carry out the experiment:
- It is rich in organic matter.
- Also in metals, nitrogen and phosphorus.
Combining them can create a material with a good electrochemical performance index. The process is as follows:
- Drying: the mud is dried and pulverized.
- Chemical modification: Potash is added as a chemical agent to make the material more porous.
- Pyrolysis: the mixture is subjected to temperatures of 800º to convert the organic matter into activated carbon.
- Mixture with sulfur: thus it is trapped in the active carbon matrix and the last step would be to integrate it into the battery electrodes.
Promising. The researchers have found that the activated carbon obtained has ideal properties to be used as a material in these batteries. Its porous structure and nitrogen doping improve the transport of electrons and ions, and the resulting material has a high sulfur content. This allows the battery to have great electrochemical stability.
That is to say, one of the big problems of this technology, the low conductivity of sulfur for the cathode, is something that mitigates the matrix created from the Villaviciosa de Córdoba sludge. And because its raw material is what it is, it is easier to recycle than other conventional batteries for which you have to develop tadjacent technologies for sustainability. According to the researchers, it is an avenue worth exploring because “triple the storage capacity of a lithium-ion battery”.
“It is a great advance that we achieved from a waste that we considered problematic” – IQUEMA researchers
Beyond the poop. Considering the results, it is likely that we will see more studies in the same direction. It is something that solves a double problem: the municipal waste management by converting it into a key material to solve one of the challenges of lithium-sulfur batteries. And the interesting thing is that IQUEMA has not remained only in the sludge of the sewage treatment plant.
Previously explored the potential of agroindustrial byproductslike the olive pits and avocados, but also almond and pistachio shells. The problem is that these materials are already in demand in other sectors (such as composting or heating), and that is where the great advantage of human excrement lies: “no one” wants them.
Images | ACE, Thomas Freres
In Xataka | No, China has not turned off the tap on batteries for electric cars. The reality is much more complex
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