It is a well-known fact that water and electricity do not mix, but new research suggests ice is a flexoelectric material — which, in layman’s terms, means it can produce electricity.
It’s unlikely that you will be able to save much in terms of household bills by rubbing two ice cubes together, but it has been shown that bending or otherwise deforming a sheet of ice can generate an electrical charge. Not only could this pave the way for novel technology, but it could improve our understanding of lightning and other natural phenomena, according to researchers writing in Nature Physics.
"We discovered that ice generates electric charge in response to mechanical stress at all temperatures,” Xin Wen, a member of the ICN2 Oxide Nanophysics Group and one of the lead researchers involved in the study, said in a statement.
Electricity From Ice
While the charge produced from ice alone may be enough to impact natural phenomena like lightning, it is too small to be incorporated into electronic devices. However, a subsequent paper published in Nature Materials suggests “doping” ice with sodium chloride (or salt) increases its flexoelectric coefficient — the material’s ability to produce electrical charge — 1,000 times over.
“The high flexoelectricity of saline ice brings the vision of harnessing ice power one step closer to reality, and may also be relevant to the electrical activity of ice-covered terrestrial regions and icy ocean worlds such as Europa or Enceladus,” the study’s authors wrote.
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Generating an Electric Charge
Ice is not piezoelectric, meaning it does not develop a charge when placed under pressure. However, by bending thin sheets of ice, scientists were able to generate an electrical charge and demonstrate a level of flexoelectricity the researchers describe as “comparable” to piezoelectric materials like titanium dioxide and strontium titanate, materials often used in sensors and capacitors.
“Flexoelectricity has two contributions: ionic (from small shifts of the atoms) and electronic (from shifts in the electron clouds),” explained co-author Anthony Mannino, a Ph.D. student in the Department of Physics and Astronomy and the Institute for Advanced Computational Science (IACS) at Stony Brook University. “In ordinary ice, the electronic part dominates — when the ice is bent, the electrons redistribute to create polarization while the atomic configuration stays relatively rigid.”
The researchers say this process could help explain how lightning forms. Because while it is known that electric potentials build up in thunderclouds when small ice particles collide with larger graupel particles (or soft hail), how exactly those particles become charged remains a mystery. Now, it appears that an electric charge could be generated when particles are deformed irregularly.
The team also discovered a second method for generating electricity: ferroelectricity. At exceptionally low temperatures of negative 113 degrees Celsius (negative 171.4 degrees Fahrenheit) and below, a thin “ferroelectric” layer enables the surface of the ice to acquire a natural electric polarization.
“In ferroelectric ice, the orientation of the water molecules allows the ionic part to play a larger role, so both electrons and ions contribute significantly to the polarization,” said Mannino.
A Power Couple
Appearing in the form of snowflakes, frost, and glaciers, ice is one of the most abundant materials on the planet — indeed, it makes up approximately 10 percent of the Earth’s surface. The problem is that the ice itself does not seem to be the most efficient at generating electricity.
This changes with the addition of sodium fluoride. A solution containing 25 percent salt had the ability to generate 1,000 times the electrical charge of pure ice and 1,000,000 times as much as salt alone. The reason for this lies in the movement of salty water when ice is bent — a process that unlocks water molecules and salt ions, enabling them to pass from compressed areas to stretched areas.
There are some issues to iron out — the efficiency drops significantly over time, for example — but the researchers say it could offer an alternative material for low-cost sensors and energy-harvesting devices. As the researchers wrote, “searching for renewable, sustainable, and low-cost energy is among the most pressing challenges for modern society.”
Read More: Arctic Lightning Linked to Climate Change
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- Nature Physics. Flexoelectricity and surface ferroelectricity of water ice
- Nature Materials. Streaming flexoelectricity in saline ice
