Researchers develop high-energy magnesium batteries that can store more energy

A recent breakthrough in magnesium-based energy storage technology promised to make the tried-and-tested design much more competitive with lithium-ion systems. The updated battery achieved its vast increase in storage capacity and energy discharge by using an organic electrode alongside chloride-free electrolytes.

High-energy magnesium batteries derived from the new design can be used in all kinds of roles. They could be fitted aboard increasing numbers of electric cars, planes, and boats to provide power to engines and electrical system. Or they could store excess electricity produced by renewable energy sources for later distribution to the power grid.

It was the very first magnesium battery designed to use this combination of organic-based electrical conductor and a reduced number of electrolytes. Researchers at the University of Houston (UH) decided to dispense with the common use of chloride to store and transport electric charges.

UH associate professor Yan Yao explained that chloride was used in almost all magnesium batteries. But his team confirmed that the chloride-based chemically compound actually hampered the performance of the electrolyte. In the absence of chloride, the remaining electrolytes started performing better. (Related: New biological batteries use energy inspired by electric eels, could be used on next-gen robots, bio-implants.)

A new magnesium battery that ditches chloride electrolytes and uses organic electrodes

After Yao and his research team removed all traces of chloride from the electrolyte, they paired up the charge-carrying material with organic cathodes and a metal anode. The cathodes were made from quinone polymers, while the anode was magnesium.

In the experiment, a kilogram of chloride-free electrolyte and organic-metallic electrode could hold 3.4 kilowatts of energy. The peak discharge of this battery was 243 watt hours. It could be charged and discharged for 2,500 times without losing efficiency.

These findings could lead to the development of a high-energy magnesium battery, which researchers have been dreaming about for many years now. Magnesium offered a number of advantages over lithium when it came to the storage and discharge of electrical energy.

Magnesium happens to be much more abundant than lithium. It is also easier to extract from sources. These qualities make it much cheaper as a material for mass production.

Furthermore, magnesium is the safer element. A lithium-ion battery often developed dendrites that could puncture its interior, which could cause the device to blow up or catch fire. But a magnesium battery does not display this behavior.

Switching out molybdenum sulfide in magnesium battery cathodes for organic compounds

The drawback to using magnesium in batteries was their inability to store and discharge the same amount of energy as lithium-ion batteries. Yao attributed this to the materials that made up the previous generation of cathodes and electrolytes.

A cathode acts as the battery’s point of entry for an electric current. Electrolytes serve as the bridge between the cathode and the anode.

Magnesium batteries have been using molybdenum sulfide in their cathodes for almost two decades now. The material cannot match the power output and energy storage capacity of their counterparts in lithium-based systems.

Fortunately, new research pointed out the potential of certain organic materials to store large amounts of energy at ambient temperature. The UH researchers investigated the reason for this superior performance to molybdenum sulfide.

Upon testing, organic polymers delivered higher voltage than the traditional cathode for magnesium batteries. Yao and his team indicated future plans to raise the specific capacity and voltage of these materials so that they could compete against lithium-ion batteries.

“Through (the) optimal combination of organic carbonyl polymer cathodes and Mg-storage-enabling electrolytes, we are able to demonstrate high specific energy, power, and cycling stability that are rarely seen in Mg batteries,” the UH researchers concluded in their paper.

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