Why do we need lithium ion batteries and can we make them more sustainable? By Heather O'Donoghue

In 2019, the Nobel Prize for Chemistry was awarded to Whittingham, Goodenough, and Yoshino for the development of the lithium ion battery. These batteries enabled a “wireless revolution” and they are used to power the devices many of us use on a daily basis, for example laptops and mobile phones. Electric and hybrid cars are also powered by lithium ion batteries. Their capacity for storing electricity makes them ideal for trapping the energy produced by renewable energy sources, such as wind, solar, and hydroelectric power.


In a traditional battery, an acid and a base react chemically to provide electricity. However, the acid and base eventually become neutralised, leaving the battery permanently depleted of power.


A lithium ion battery is powered in a different way. There are three main components; the cathode, or positively charged pole, which contains a lithium metal oxide e.g. LiCoO2; the anode, or negatively charged pole, which is made of a carbon ion sink e.g. graphene; and an electrolyte coated separator often made of a plastic – such as polypropylene – soaked in an organic solvent. The electrodes exchange ions and electrons to create an electrical potential that powers the battery without causing chemical degradation internally. This is called intercalated electrode technology and it is an excellent example of electrochemistry in action.


As they are rechargeable, these batteries are automatically more sustainable than their traditional counterparts. Traditional batteries contain many hazardous chemicals, including cadmium, mercury, and lead. When batteries are disposed of incorrectly, these toxic chemicals are leached into the environment poisoning groundwater and soil. The majority of retailers and local councils provide recycling facilities for batteries but there is still no guarantee they won’t poison the environment.


Lithium ion batteries are far from perfect. There are a number of challenges still being worked through to improve them.


Current battery technology means that there is a limited electrical capacity even in the highest performing batteries. Capacity is limited to the point that these batteries cannot compete commercially with fossil fuels in the current electricity and fuel markets. Electric cars, powered solely by lithium ion batteries, can only travel certain distances before needing to be recharged. Charging the batteries takes time and fast charging technology hasn’t been optimised yet to be safe and effective. This means many consumers are hesitant about buying electric cars. Apart from Norway and The Netherlands, most European countries are significantly lacking in public charging infrastructure.


Mining lithium has significant environmental costs of its own. The earth is rich in lithium but only a third of that is in a form that can be mined. 87% of the available lithium is found in brine waters, primarily in the salt flats of South America. It has to be extracted from the ground in a process that is similar to fracking, the controversial method of extracting shale gas from the earth. The process uses a lot of water and disrupts the local environment for between 18 and 24 months.


Mining remains cheaper than recycling, which means that lithium ion batteries are rarely recycled responsibly. Lithium and cobalt, both components of these batteries, are toxic to the environment so if they are not reliably recycled then they can create an environmental risk of their own. There are 2 million electric cars now registered globally. When the batteries in these cars burn out and have to be replaced, what will the environmental impact be?


What if there was an alternative to the lithium ion battery? What if the electrochemical principles of the lithium ion battery could be applied to a cleaner, more environmentally responsible set of materials to produce the same or better results? One company, Aqua Battery, are looking at a battery powered by water and regular table salt (NaCl). They are currently trialling their technology in Delft, a small city just south of The Hague in The Netherlands.


Aqua Battery’s product, the BlueBattery, produces and stores electricity based on the osmotic potential of water with different levels of salt. Three tanks of water – one of fresh water, one of concentrated salt water, and one of dilute salt water – are combined with a specialised membrane. To charge it, the dilute salt water is split with electricity – in a process known as electrodialysis – into concentrated salt water and fresh water as it passes across the membrane. During discharging, the opposite happens, with fresh water and salt water undergoing a process of reverse electrodialysis. This results in them combining back into dilute salt water as they move back through the membrane.


The battery is only at the proof of concept stage. This means it may be a few more years before it becomes commercially available. But the concept of a sustainable water based battery is very promising. Currently the limited capacity of rechargeable lithium ion batteries means that the storage of electricity generated from renewable sources is not commercially competitive. But if there was a cheap, sustainable electricity storage solution, like the BlueBattery, renewable electricity could start to seriously compete with fossil fuels.


There is a clear need for a sustainable battery to allow us to meet the global decarbonisation goals set out in the 2015 Paris Climate Accord. By providing a solution to the challenge of storing electricity generated by renewable resources, batteries can contribute to the green revolution. But there must not be a different environmental cost imposed by the use of this technology. Innovations like the BlueBattery could be the answer. Perhaps there is another clean, sustainable battery alternative waiting to be discovered. Engineers and chemists are hard at work trying to find the next innovation in rechargeable battery technology. Hopefully in the not too distant future a solution will be available and our reliance on fossil fuels will be diminished.


References

2019 Nobel Prize: https://www.nobelprize.org/prizes/chemistry/

UK Battery Recycling Information: https://www.gov.uk/battery-waste-supplier-reponsibilities

National Geographic Report on Battery Innovation: https://www.nationalgeographic.com/science/2019/10/partner-content-audi-nl-the-cost-of-batteries/

Guardian Article on Electric Car Use: https://www.theguardian.com/sustainable-business/2017/aug/10/electric-cars-big-battery-waste-problem-lithium-recycling

Aqua Battery Website: https://aquabattery.nl/bluebattery/

BlueBattery Technology: https://aquabattery.nl/bluebattery/

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