In last half-decade or so, we have made significant strides in the field of renewable energy, and thus to an extent reducing our dependence on fossil fuels. Even though we are far away from attaining total dependability on renewable energy, with recent innovations like wind farms, solar panels and tidal turbines that can now generate energy much more efficiently than a decade ago.
But, there laid a major roadblock in transforming the fossil fuel dependent economy into a sustainable renewable energy-dependent economy, that is the limitation of the present day energy storing technology, or simply put our batteries aren’t good enough.
In recent years, we have seen a plethora of academics and innovators announcing the next “breakthrough” in battery technology. Most of them looked very impressive on paper, but had very little impact, in reality, forcing inventor and entrepreneur Elon Musk to ridicule these so-called innovations by saying, “everything works on PowerPoint. You know, I could give you a PowerPoint presentation about teleportation to the Andromeda Galaxy. That doesn’t mean it works”.
Elon Musk definitely has a strong point as most of these innovations remain theoretical, “The battery breakthrough of the week, battery breakthrough du jour. When somebody has like some great claim that they’ve got this awesome battery, you know what, send us a sample. Or if you don’t trust us, send it to an independent lab, where the parameters can be verified. Otherwise, STFU,” he stated.
However, there is hope after all. On October 11, researchers at Massachusetts Institute of Technology (MIT) under the lead authorship of Zheng Li, published a paper in the journal Joule titled ” Air-Breathing Aqueous Sulfur Flow Battery for Ultralow-Cost Long-Duration Electrical Storage “, which explains the development of an “air-breathing” battery. These batteries can store electricity for months, for about a fifth of the cost of current technologies.
According to experts, air-breathing technology will finally be the battery breakthrough we all have been hoping for to transform and in fact, save the planet itself. These new batteries are capable of storing electricity for long periods of time at about $20 a kWh, compared to the current cost at the cheapest, which is about $100 per kilowatt hour.
Coming to the invention, a battery is essentially comprised of three basic components, a cathode, an anode, and an electrolyte. The “air-breathing” battery uses cheap and very abundant sulphur dissolved in water as the anode. At the cathode, an aerated liquid salt solution continuously takes in and releases oxygen that balances charge as ions shuttle between the electrodes. This oxygen flowing into the cathode causes the anode to discharge electrons to an external circuit and the oxygen flowing out sends electrons back to the anode, recharging the battery, explains MIT News.
“This battery literally inhales and exhales air, but it doesn’t exhale carbon dioxide, like humans — it exhales oxygen,” said Yet-Ming Chiang, co-author of a paper to MIT News .
Where it gets really interesting is the total cost involved in creating this battery, which is essentially the combined price of cathode, anode and the electrolyte. Currently, the most commonly used lithium-ion batteries, have a cost of about $100 for each kilowatt-hour of energy stored.
According to Chiang, this meant maybe we weren’t focusing on the right thing because of the ever-increasing chemical cost in pursuit of high energy-density. “We said, ‘if we want energy storage at the terawatt scale, we have to use truly abundant materials,”, said Chiang pointing to the beginning of the development back in 2012.
The first major milestone towards the invention came when the research team decided to use sulphur, a widely available material as the anode, especially considering its lowest cost per stored charge next to water and air. However, a major challenge remained in finding an inexpensive liquid for the cathode, that can remain stable while producing a meaningful charge. Thus the research settled on one of the most familiar compounds to us potassium permanganate.
But, if used as a cathode material, that compound is “reduced” — a reaction that draws ions from the anode to the cathode, discharging electricity, and the reduction of the potassium m permanganate is impossible to reverse, making the battery non-rechargeable.
Surprisingly the eureka moment arrived when they research team found that the battery was, in fact, recharging, due to an unexpected oxygen reaction in the cathode, which was running entirely on air. “I said, ‘Wait, you figured out a rechargeable chemistry using sulphur that does not require a cathode compound?’ That was the ah-ha moment,” Chiang recalls of the breakthrough.
The prototype they created is currently only about the size of a cup. However, according to Chiang, flow batteries are highly scalable and cells can be combined into larger systems. Since this battery can hold the charge for many months, its initial application will be for storing electricity generated from solar and wind power sources.
As the battery can discharge over months, the best use may be for storing electricity from notoriously unpredictable wind and solar power sources.