- Education and Science
No Foolin - New Na-Mg Hybrid Battery Benefits From Fool's Gold
Energy Storage Solutions for Solar and Wind
The intermittent nature of energy generated by solar PV cells and wind turbines amplifies the demand for cost-effective energy storage solutions. As a result, research into battery technology is advancing at a frenetic pace. Some researchers are devoted to improving existing batteries while other focus on entirely new battery types.
Batteries that use exotic or scarce compounds require stable prices for the materials. However, burgeoning demand often pushes prices higher. The ideal solution is an efficient battery made from inexpensive and abundant materials. According to research published in the journal Chemistry of Materials, scientists from ETH Zurich and Empa believe they have developed just such a battery. It employs a magnesium anode, sodium-based electrolyte and an iron sulfide nanocrystal cathode.
Na-Mg Battery Uses Abundant Raw Materials
A magnesium anode is as much as 15 times cheaper than a lithium one. Iron sulfide nanocrystals are inexpensively made by combining metallic iron and milled sulfur. Iron sulfde is commonly known as iron pyrite or "fool's gold." Furthermore, in a Na-Mg battery, aluminum foil replaces the more expensive copper foil required in a Li-ion battery.
Much of the current supply of lithium comes from just a few countries, including China and South Africa. The abundance of the Na-Mg battery's primary components, magnesium, sodium, sulfur and iron, is undisputed. Indeed, in terms of mass, iron is the fourth most common element on the planet, while magnesium is sixth and sodium is seventh. Finally, sulfur is the 15th most abundant substance on Earth.
How the Na-Mg Battery Works
As a Na-Mg battery discharges, sodium ions move through the electrolyte to the cathode. During recharging, the iron sulfide releases those sodium ions back into the electrolyte. The success of a new battery design hinges in part on its ability to repeatedly recharge without degradation. In testing, an Na-Mg battery endured 40 charge-recharge cycles with zero degradation.
One drawback to the current design is power output, which is lower than that of a lithium-ion battery of the same size. However, researchers assert that the technology is scalable, so very large batteries could be developed. Again, costs are minimized by the use of relatively low-cost materials.
Researchers assert that massive batteries are possible, theoretically large enough to store the entire output of a nuclear power plant.
Promising New Battery Design
Dr. Kovalenko, a professor in the Department of Chemistry at ETH Zurich, states that "the battery's full potential has not been exhausted yet." He believes that further refinement of the electrolyte solution will both increase the voltage and extend the life of the novel Na-Mg battery design.