A new version of high-energy magnesium batteries may find promising applications in wide range of electric vehicles and battery storage for renewable energy systems, according to researchers at University of Houston (UH) and the Toyota Research Institute of America.
The new high-energy magnesium batteries, detailed in the recent issue of journal Joule, has been reported to use an organic electrode, while operating with limited electrolytes. The researchers said that such change allows the battery to store and discharge extremely high energy compared to previously known magnesium batteries. Another change from the traditional magnesium batteries is the use of chloride-free electrolyte which enabled the discovery.
The research team has also confirmed that the sluggish performance of the traditional batteries is due to the presence of chloride in the commonly used electrolytes, according to Yan Yao, associate professor of electrical and computer engineering at UH. The issue the team tried to address was the impact of universally used chloride.
For testing organic Quinone polymer cathodes with a magnesium metal anode, the researchers used a chloride-free electrolyte. They reported that around 243 watts hours per kilogram were delivered, while the power measured at up to 3.4 kilowatts per kilogram. Further, the researchers found that stability of the battery was efficient through 2,500 cycles.
Researchers around the world have spent years seeking for high-energy magnesium batteries, to take advantage of the superior properties of magnesium over lithium, the metal used in present-day lithium-ion batteries.
Magnesium are low cost and more abundant in nature, which is not prone to breaches in its internal structure called dendrites, whereas lithium is more prone to such breaches causing the batteries to explode and catch fire. However, magnesium batteries won’t be ready for commercial competition until they can store as well as discharge high amounts of energy. Yao said that a stumbling block of the existing batteries is cathode and electrolyte materials.
As reported in the journal, the team has been able to show high power, specific energy, and cycling stability – rarely observed in magnesium batteries – through ideal combination of electrolytes that enable Mg-storage and cathodes of organic carbonyl polymer. Until now, Chevrel phase molybdenum sulfide is considered to be the best cathode for Mg-batteries, developed almost two decades ago, but it did not have enough power and energy storage capacity to be more advantageous over with Li-batteries.
Recent reports had suggested that organic cathode materials offer relatively high storage capacity at room temperature, making the researchers more curious about it. When tested, it was found that organic polymer cathodes offered higher voltage compared to Chevrel phase cathode. According to the researchers, future research will focus on improving voltage and specific capacity for Mg-batteries to be able to compete against lithium variants.