The world of hardware reshapes itself as fast as it ever has nowadays. Pocket computers exponentially increase in power seemingly every few months, while our laptops can now fold completely in half and masquerade as a tablet. However, as far as hardware ever reaches, batteries always seem so stagnant. Now, though, promising research into sodium-air batteries could lead toward the battery revolution we’ve all been waiting for.
Aside from, for example, standard AA or AAA batteries, lithium-ion batteries are the go-to power source for our most prized mobile devices. They are rechargeable, and last an acceptable amount of time before cutting out right in the middle of an important phone call. Though our smatphones and tablets have an acceptable lifetime, sometimes you accept what you’re given rather than what you actually want. An iPhone 5 can last around 8 hours of 3G, LTE data use or talk time, or for 10 hours of video playback, or 40 hours of audio playback.
When you’re using some combination of all those features — as anyone with a smartphone and a long commute is fully aware — the phone’s battery life is woefully short. Because of the way a lithium-ion battery generates power — through chemical reactions — the amount of power generated has a ceiling. This means that at some point, a lithium-ion battery will be giving literally the maximum amount of power it can. A ceiling means that, eventually, our devices will require more power than the battery can give.
In order for a battery to work, it needs to exchange an electron, because that usually generates a form of energy that is harvestable. However, the weight of a material is an important factor when designing a battery, as, obviously, a heavier battery means a heavier, less desirable device. So, in order to generate energy from a light material, you turn to oxidation. Considering oxygen abounds, you don’t need to include something that will be the oxidation catalyst, which makes the battery lighter. This type of battery, rather than the usual suffix of -ion, carries the self-explanatory suffix of -air. Scientists theorize that, in part due to not requiring a catalyst in the battery, a higher yield of energy can be generated. Whereas a lithium-ion battery has a capacity of around 200Wh/kg, a lithium-air battery could reach all the way up to 3460Wh/kg.
Unfortunately, the chemistry behind lithium-air batteries is so complicated that researchers have begun shifting their focus to sodium-air batteries. Though the capacity of the sodium-air is much lower than the lithium-air, sitting around 1600Wh/kg, it’s at least significantly higher than a lithium-ion, and much easier to make than the lithium-air. One end of the battery has a sodium electrode, on which an electrolyte is sandwiched underneath a carbon electrode that oxygen can travel through. The electron travels around the battery, the ionic metal dissolves into the electrolyte which in turn travels to the carbon electrode and hits the oxygen.
Though this is still in an experimental form, researchers found that not only does the sodium-air hold more charge than a lithium-air battery, but is easier to charge as well. It was mentioned above that lithium-air has a theoretical density of more than double the sodium-air, but as it turns out, the sodium-air has a higher density in practice (that isn’t to say that, one day, lithium-air won’t reach its enormous density destiny).
At the moment, though, a sodium-air can only be charged around eight times before it dies for good. Hopefully, scientists will be able to figure out why that is, and bring us a battery that can power our mobile devices for long periods of time without us having to conserve the power after a long night out
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