A Breath of Fresh Air on the Design of Lithium-Air Batteries

Eric Chien
By Eric Chien March 24, 2019 16:22

A Breath of Fresh Air on the Design of Lithium-Air Batteries

We’ve all been there before: waking up at the crack of dawn, taking a sip of coffee, and trudging all the way to class or work only to realize that our cell phone never got charged last night. Blame it on that lithium-ion battery!

 

The typical lithium-ion battery is made of three major components: a lithium-based negative electrode, a positive electrode, and an electrolyte separating the two. When the battery is discharging, lithium ions and electrons travel from the negative to the positive end; the ions move through the electrolyte while the electrons move through an outer circuit to power the electronic. When the battery is charging, the ions and electrons take the same paths except they travel from the positive to the negative end.

 

While the capacity and power of lithium-ion batteries have improved, recent research has found a promising new alternative: the lithium-air battery. Primarily composed of lithium and oxygen, the lithium-air battery boasts a lighter weight and theoretically at least 10 times the energy density (energy capacity per unit mass) of traditional lithium-ion batteries.

 

But there are a few major reasons why this battery is still so theoretical. Chemical discharge products and byproducts corrode the cathode of the battery. Furthermore, a significant amount of energy is lost to heat when charging, and key components and chemicals within the battery decompose quickly. Clearly, the lithium-air battery is nowhere near perfected.

 

However, new developments from the University of Waterloo, with lead author Chun Xia, PhD, aimed to resolve many of these pertinent issues with a battery redesign. The new design attempts to create a more sustainable and stable battery capable of maintaining its initial capacity after long term use.

 

The most significant change is the use of lithium oxide (Li2O) rather than lithium peroxide (Li2O2) as a discharge product. Not only is Li2O less likely to decompose the electrolyte or corrode the positive electrode, but it also boosts the battery’s energy density—theoretically even exceeding the energy density of fossil fuels like gasoline. However, the production of Li2O2 is favorable to the production of Li2O at ambient conditions. Thus, the team increased the battery operating temperature to 150 °C, causing the production of Li2O to be favored. Furthermore, the team created a nickel nanoparticle-based positive electrode to catalyze and decrease the energy needed for breaking up oxygen-oxygen bonds, a necessary step for the production of Li2O.

 

The results of this study and other studies focused on the development of the lithium-air batteries help to slowly but methodically bring to life the concept of a battery capable of immense power and efficiency. While it is still a little early to imagine all the implications that such a battery could bring to everyday life, lithium-air batteries could significantly help with sustainability initiatives on Earth. For the auto industry, a lithium-air powered car capable of producing as much power as gasoline may provide the spark for expanding the environmentally-friendly car market. For the power industry, a lithium-air solar cell battery capable of greater energy efficiency may allow solar energy to be competitive against fossil fuels. It is still too soon to say when this will become a reality, but findings like the one in this study are bringing us closer, inch by inch.

Eric Chien
By Eric Chien March 24, 2019 16:22
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