Renewables to get a jolt from aluminium batteries
By Mario Carr - October 2019
When a new type of aluminium battery hits the market, it will be a game-changer for solar and wind power industries.
While lithium-ion batteries are ideal for powering mobile devices, they are not the best choice for larger applications. The high cost of power storage, limited cycle life and safety concerns with these batteries has slowed the pace of growth for several wind and solar renewable energy projects.
But that’s all about to change.
An aluminum battery concept developed at Chalmers University of Technology in Sweden and the National Institute of Chemistry in Slovenia could make these storage devices more affordable and efficient.
“The material costs and environmental impacts that we envisage from our new concept are much lower than what we see today, making them feasible for large scale usage, such as solar cell parks, or storage of wind energy,” said Chalmers Physics Professor Patrik Johansson.
Disposal of these batteries will also be more environmentally friendly since there’s already a strong world-wide aluminium recycling program. Aluminium can be transformed into many different products.
On average around the world, aluminium can be recycled 50-70 times, whereas lithium is recycled less than once. The problem with lithium is that there is a limited market for recycling. There are also safety concerns with lithium batteries. These batteries have been known to catch fire and explode. Aluminium batteries on the other hand are safer and more efficient at transferring energy.
The performance characteristics of aluminium ion batteries can be superior.
When it comes to holding a charge, aluminum ion batteries last longer. Lithium-ion batteries typically lose 80 percent of their capacity after 500-1000 charging and discharging cycles. A Stanford University aluminum ion prototype battery lasted more than 7,500 cycles without any loss in capacity.
Aluminium ion batteries can also hold more energy. The theoretical energy density potential for aluminium-ion batteries is 1060 Wh/kg while that of lithium-ion batteries is 406 Wh/kg. Inside the battery, lithium ions can only provide one electron at a time, whereas aluminum ions provide three electrons at a time.
Aluminum is also more economic than lithium since it’s readily available comprising eight percent of the earth’s crust. It’s also the third most abundant element found on the planet behind oxygen and silicon. Compared to lithium, aluminium is less expensive to mine and refine. Globally, aluminum costs about US$2 per kg, whereas lithium costs US$300 per kg.
The breakthrough the researchers found, comes from better battery chemistry. Inside every battery there are two electrodes, anode and cathode, separated by an electrolyte. The electrolyte is a substance that chemically reacts with the two electrodes to create electricity. When the battery discharges, the cathode becomes positive, while the anode becomes negative.
Previous aluminium batteries used aluminium as the anode and graphite as the cathode. Unfortunately, graphite doesn’t provide enough energy to create useful battery cells. If the graphite is replaced by an organic molecule called anthraquinone, researchers point out, the battery will have the ability to store more energy.
“Because the new cathode material makes it possible to use a more appropriate charge-carrier, the batteries can make better usage of aluminium’s potential. Now, we are continuing the work by looking for an even better electrolyte,” said Chalmers researcher Niklas Lindahl.
Many universities are also researching the potential benefits of aluminium batteries. Last December, researchers at UNSW in Sydney, Australia, announced that rechargeable aluminium-ion batteries are a possibility in the future with renewable energy storage.
They managed to use a large organic chemical compound as part of the battery that stores energy, something that had previously baffled researchers.
“Developing batteries using aluminium has received a lot of expectation for delivering high energy to price ratios,” said UNSW Chemistry Professor Dr. Kim.
The race is on, to find a low cost and efficient energy storage solution. It seems that it won’t be too long until solar and wind renewable projects will get a new lift from aluminium ion batteries.
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