We have spent decades, if not centuries, using the combination of ice and salt for different purposes. One of them is to preserve food and the other to prevent the ice on the roads from being slippery. Although it may seem contradictory, the answer is physical.
Pure water freezes at 0°C. Its molecules form an ordered crystalline network: ice. For its part, salt is made up of ions and when we pour it on the ice, these ions get between the water molecules, making it difficult for them to re-form the rigid structure of the ice.
For the mixture of water and salt to freeze, more cold is needed. That is to say, freezing point drops below 0°C (it can go down to about -21° C in ideal conditions). This means that ice, at 0°C, needs a much lower temperature to remain solid. And it melts.
Now, this combination could give us an even more interesting use. A team of Spanish and Chinese scientists have discovered a physical principle capable of generating electricity thanks to this combination. According to a study, published in Nature Materials, the interaction between salt and ice can create an electrical charge, opening the door to a new way of obtaining energy from our environment.
Intuition tells us that salt melts ice by lowering its melting point. But what happens at the molecular level is a dance of electrical charges. The results of the study, led by the Catalan Institute of Nanoscience and Nanotechnology, demonstrates that when a salt crystal (such as sodium chloride, NaCl) comes into contact with ice, a contact electrification phenomenon occurs.
The key is that the salt ions (the sodium cation, Na⁺and the anieithern chloride, Cl⁻) do not diffuse into the ice at the same rate. Cl ions⁻ They have greater mobility and penetrate slightly mtos in the ice crystal lattice than Na ions⁺. This separationeithernfYophysics of positive and negative charges generates an imbalance, known as a double layer.andelectrical, creating a voltage potential difference. In essence, the salt ice becomes an electrochemical battery.Yomica. A very basic one, but a stack, nonetheless.
The team, led by Gustau Catalán, designed different experiments in which they used insulating materials (such as Teflon) against ice with different concentrations of salt. The results were conclusive: the presence of salt increased the generation of electrical charge by orders of magnitude compared to pure ice. A simple salted ice cube can generate voltages on the order of several tens of millivolts. While it is not a huge amount, it is perfectly measurable and proves the concept irrefutably.
This finding transcends the merely academic. The ability to generate electricity from such a ubiquitous and low-cost process raises interesting scenarios. For example, will allow the development of autonomous sensors in cold environments for use in the Arctic or in high mountains, powered by the ice itself and the surrounding sea salt, without the need for conventional batteries.
The phenomenon could play a role, until now unknown, in the formation of static electricity in cloudsinfluencing ice formation processes and perhaps even the genesis of lightning.
It would also be useful in materials for energy harvesting. Materials or surfaces designed to maximize this effect could be developed, capable of capturing mechanical energy. (like wind moving salt ice particles) and convert it into electrical pulses useful for microdevices.
“In addition, this phenomenon could improve our understanding of natural processes in frozen environments, such as glaciers – concludes a statement -, and of the presence of electrical activity on the icy moons of our solar system, such as Europa and Enceladus”.