This Novel Aluminium Battery Might Be The Game Changer We've Been Looking For
Eco-friendly with a high-energy density and cheap. What's not to love?
For humanity to kick its fossil fuel addiction once and for all and save this beautiful planet from ourselves, we need batteries. Lots and lots of batteries. But we have a bit of a problem. You see, our current battery technology of choice, lithium-ion batteries, isn’t perfect. While they are quite energy-dense, last long enough and charge at a decent speed, they are also expensive and environmentally dubious. In other words, for us to genuinely save the planet, we need to find a better battery than lithium-ion. But luckily, some Australian and Chinese researchers may have found this holy grail of battery technology in the form of an aluminium radical battery. However, what is an aluminium radical battery? And why could it be the future of battery technology?
Let’s start with lithium-ion batteries: what’s wrong with them?
Well, lithium-ion electrolyte (the bit that stores the energy in the cell) must be wet-coated onto the cathode and anode during manufacturing. This means they need to fully dry before being finally assembled, so lithium-ion factories use giant oven-like machines to do this. This means lithium-ion cells take longer to make, use more energy, produce more emissions and cost more to make than alternatives that don’t need this drying process. Lithium-ion cells also need to be doped with heavy metals, such as cadmium and cobalt, to achieve high energy densities and fast charge times. These metals are toxic, making disposal or recycling of lithium-ion batteries incredibly difficult. Moreover, the mining of these metals causes toxic compounds to leach into the local water table, poisoning it. There are also humanitarian issues surrounding some of these metals, such as cobalt, as some cobalt mines in developing countries have been found to be violating human rights. On top of all of this, while their cost has plummeted over the past decades, lithium-ion cells are still too expensive, bulky and slow-charging to fully replace many fossil fuel technologies like combustion engines. Finally, one of the last significant issues with lithium-ion batteries is that their electrolyte is highly flammable; this means the cells can catch fire and burn ferociously for hours or even days if punctured, short-circuited, overheated or damaged.
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But this is where researchers from Flinders University in South Australia and Zhejiang Sci-Tech University in China come in. These guys have developed the world’s first aluminium radical batteries that use water-based electrolytes that are fire-retardant and air-stable, and they seem to solve all the problems of lithium-ion.
Technically, these batteries are a type of aluminium-ion battery, which have existed for decades. In theory, aluminium-ion batteries are far better than lithium-ion packs, as they have a way higher upper limit to their energy density, and as aluminium is far more abundant and easier to mine than lithium, they should also be cheaper. However, the cathodes for these batteries were highly inefficient, leading to lower energy densities, short lifespans and slow charging.
These researchers solved these problems by using a novel approach. Rather than doping the cells with heavy metals, as we did to solve the problems with lithium-ion, they used stable radicals, a class of organic electroactive molecules which are relatively new and never before used in aluminium batteries. This means that, while the battery is still technically an aluminium-ion cell, it actually stores and discharges energy through a reversible redox reaction with an organic nitroxide radical called TEMPO.
Now, I don’t quite understand the science here, and unless you hold a PhD in material science, neither will you. All you need to know is this battery is built using readily available materials and no toxic materials. This makes it more eco-friendly and potentially far cheaper to produce than lithium-ion cells.
But that isn’t the surprising thing about this battery.
You see, this experimental prototype cell was bench-tested, and it has some surprisingly good specs. The cell delivered a stable voltage of 1.25 V and had a lifespan of 800 charge cycles (after which it lost 22.4% of its capacity). This makes it as robust as the low to mid-range lithium-ion batteries we use today. But this cell is also incredibly energy-dense, at 110 mAh per gram. To give some context here, Tesla’s 4680 cells sit at 73 mAh per gram, making this cell 50% more energy-dense!
So, Aluminium radical batteries are more eco-friendly, potentially cheaper, just as robust and way more energy-dense than lithium-ion batteries. But don’t forget, aluminium radical batteries have only just been invented and are yet to be developed and refined, so it is possible that in the near future, they can live longer than lithium-ion cells or be even more energy-dense!
Does this mean the future going to be powered by aluminium radical batteries? Well, we don’t yet know how fast they charge, and if they don’t charge fast enough, they could be utterly useless. What’s more, their lifespan would need to more than double for them to be used in EVs or grid-level energy storage facilities. While there is a chance these batteries are a development dead end, with no solution to these potential issues, there is also a chance that these are easily solvable, and our future is powered by these brilliant batteries. We shouldn’t have to wait long to find this out either, as the researchers seem to be gearing up to develop biodegradable soft-pack batteries from this technology. So, pay attention to this space! It could just spark a revolution.
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Sources: ACS Publications, Science Daily, Electronicsforu, UPS Battery Centre, Tycorun, Inside EVs, Inside EVs, Cenex