Arguably an important – and often overlooked – strategy for achieving our sustainable energy goals rests with technological advancements in batteries. The inability to store and transmit renewable energies are a major hurdle to clean energy because the production of renewable energy doesn’t always coincide with the electrical demands of the population. Improvements in battery tech will help renewables to answer our energy needs, even when the source isn’t live.

Contemporary batteries are comprised of lithium; however, they are costly, inefficient, and limited in supply. As the development of new technologies increase at an exponential rate, it seems as if we’re approaching the physical limits of what conventional Lithium batteries can do. They work by moving lithium-ions (“Li-ions”) between the negative (the “Cathode”) and positive (the “Anode”) electrode of the battery cell. The transfer of Li-ions from the cathode to the anode, through a liquid or gel-like electrolyte, is how the electrical output is generated.

A key element to Li-ion batteries is cobalt, as it is used to manufacture the cathode. Cobalt in developing countries – particularly the Democratic Republic of Congo where 50% of the world’s cobalt is found – is often mined under exploitative life-threatening conditions by adults and children alike for next to nothing. This has led to some calling cobalt the, “blood diamonds of batteries,” with many industries attempting to use alternative methods to reduce their dependence on the element.

It is Elon Musk’s aim to remove cobalt altogether from the batteries Tesla makes. However, this is extremely difficult to achieve with Li-ion batteries, because as you decrease the amount of cobalt in the negative electrode, not only does the life cycle of the battery cell correspondingly decrease as well, but more nickel must be utilised instead. This increase in nickel impairs the cell’s ability to cool itself, thereby increasing the likelihood of overheating and combustion.

This is part of the reason that it is unlikely that Li-ion batteries will be used for future applications of batteries, especially with widespread use of electric vehicles (“EVs”) on the horizon.

The future

Silicon-ion batteries

‘Sila Nanotechnologies’ seek to create the next generation of batteries, by replacing the graphite anode in current batteries with Silicon (“Si-Li-ion”).

According to the CEO Gene Berdichevsky, “An atom of silicon can store about 20 times more lithium than atoms of carbon.” Therefore, because it takes fewer atoms to store the lithium, the batteries can be much smaller whilst also storing the same amount of energy. Given the amount of space current Li-ion batteries take up in consumer tech products, manufacturers will have more room for better features such as increased processing power.

The problem previous Si-Li-ion developers have faced is the ‘expansion problem,’ where as the silicon expands, it damages the battery cell with each charge. Sila claims to have solved this issue and, if they can successfully commercialise the battery, we will see such Si-Li-ions performing up to 40% better and charge up to nine times faster because of the anode’s reduced thickness.

Sila intends on launching their products in 2019, and perhaps the biggest advantage they have over their competitors is that they’re able to use existing battery manufacturing techniques to mass produce their Si-Li-ion batteries.

Aluminium-ion batteries

Researchers at ITRI and Stanford University are developing ultrafast aluminium-ion (“Al-ion”) batteries, made with aluminium anodes and graphite cathodes. Their major advantage is how durable they are, since they can stand up to 10,000 discharge cycles without any diminution in storage capacity, as well as fully charging within one minute.

The materials used for the battery cells are as flexible as paper and, in comparison to Li-ion batteries, incredibly stable. Researchers have demonstrated how Al-ion batteries can even withstand drilling, whilst continuing to supply electrical power, which is an astonishing breakthrough for safety.

Aluminium is the third most abundant element on the planet, taking up 8% of the Earth’s crust, ensuring that such batteries are cheaper to manufacture than Li-ion batteries. However, whilst the research is promising, it’s still in the early days of development and will be some time before it can be commercialised.

Liquid Metal batteries

Ambri, a Bill Gates-backed start-up arising out of research at MIT, seeks to replace current Li-ion batteries with a battery where all its components are in liquid form. In other words, the anode, the cathode, and the electrolyte solution – made up of molten salts – are all liquid within the battery cell.

If they can successfully launch such batteries, not only will they be much cheaper than current options – as the three liquid layers are self-segregating, cheap to manufacture and earth-abundant – they will be long-lasting since they feature a ‘no fade rate’ on full discharges over thousands of cycles.

Solid-State batteries

Perhaps the most revolutionary option would be solid-state batteries because they employ both solid electrodes and solid electrolytes; an approach completely contrasting Ambri’s endeavours.

More specifically, instead of suspending the anode and cathode in a liquid electrolyte – as with Li-ion and other next-generation batteries – the electrodes and electrolytes are compressed into three flat solid layers. The practical benefit of this novel arrangement would be a higher capacity in a smaller package or, if space is not a limiting factor, batteries that can last much longer.

Their biggest advantage is safety. They don’t produce as much heat as conventional Li-ion batteries, and there is no toxic, flammable liquid within the battery cell. This is of great interest to car manufacturers, as EVs run by solid-state batteries reduce the risk of explosion on collision and can recharge at a much faster rate than Li-ion batteries because the ions move more quickly from the cathode to the anode.

Car manufacturers that are investing heavily into this type of battery for their EVs include Toyota, BMW, Honda, Nissan, and Volkswagen. The major hurdle to overcome for researchers is the cost to manufacture. Primarily, this is because there are no economies of scale in place. Furthermore, previous testing has suggested that they can be susceptible to fluctuations in temperature, so it remains to be seen whether this form of battery could be suitable for widespread adoption.

Consequently, it is unlikely that they will be available soon, but it is an interesting glimpse into what batteries may look like 10-20 years from now.

Graphene batteries

Graphene is a structure comprising of a single layer of carbon atoms arranged in a hexagonal lattice. It is 200-times stronger than steel, more conductive than copper and as flexible as rubber. Since being discovered in 2003, it has been speculated that it can improve everything from water filtration to solar cells.

Batteries incorporating graphene would be structurally similar to conventional batteries in that they would consist of two electrodes with a liquid electrolyte solution facilitating the transfer of ions between the anode and cathode. The increased electrode density would translate to faster charging times, greater capacity and improved battery lifespan.

Whilst strictly in the realms of emerging technology, successfully implementing graphene in batteries has some people theorising how smaller devices, such as mobile phones, could be charged in a matter of seconds and bigger objects, such as EVs, could be charged in a few minutes.

Even though it is undeniably more environmentally friendly than Li-ions overall, the production method for graphene still employs the use of harsh chemicals which may not be sustainable to power the majority of EVs on the road by 2030. If researchers can find a solution to this problem, graphene could revolutionise so much more than batteries.

Conclusion

Ultimately there are many forms next-generation batteries could take, and new possibilities are continuously being discovered. Researchers looking to succeed in their aims need to ensure that their technology is practical, scalable, and not too expensive. As our technological needs are ever-growing, the only certainty is that breakthroughs in battery technologies are long overdue and hugely important.

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