Graphene in car batteries could drive the industry forward
As the clock counts down for mobility vehicles to become hybrid or fully electric, industries are left to revolutionise a single determiner – the battery.
When an EVs battery no longer has enough charge to continue running, there is still around 80% of untapped power left. To cut down on this waste, it is important to maximise the number of cycles the battery can produce.
Graphene Flagship’s industrial partners came together with the goal of developing batteries with a lifetime of 1,000 cycles, which corresponds to around 450,000km on the road.
Scientific research on graphene and related materials has been conducted in the automotive industry. Graphene Flagship, a FET flagship by the EU – set to bring graphene innovation out of the lab and into commercial applications, hosted a webinar in September 2022 where Vittorio Pellegrini, Chief Executive Officer of BeDimensional Spa, Italy, and Head of Division Energy and Composite and Production of the European Graphene Flagship, spoke about the properties and benefits for the use of graphene in car batteries.
Graphene is a very thin, strong material which consists of a single layer of carbon atoms, arranged in a pattern of six-sided shapes. It allows for faster charging and delivery of high currents due to its high level of electrical conductivity.
Next-gen lithium-ion batteries
Vittorio describes the battery as being “invented in Italy in 1799” and it was called a volt battery. “You have two metals, zinc and copper … separated by tape impregnated with salt, and this device is able to store energy and release an electrical current on demand.
“Today, modern lithium-ion batteries are similar or equal in concept with the volt [batteries] … Instead of having zinc and copper, we have two electrodes ... One electrode is made by graphite, and one electrode is made by an oxide layer, and then we have the liquid electrolyte, which allows lithium-ions to go from the cathode to the anode.
“So … the concept is the same. This device is able to store energy.”
Future battery capacity
One of the biggest challenges the team faces is the capacity of the battery.
“A conventional combustion engine car typically contains 50 litres of fuel and can be charged in a few minutes. Each litre can store and deliver 6,000-watt hour in energy.
“With the electric car you have lithium-ion batteries, each kilo of the lithium-ion battery is able to store around 200-to-250-watt power in terms of energy and you immediately realise what the challenge is.
“One litre of gas is 26,000 and one kilo of lithium-ion batteries is 200 which means that if I have to make a similar device, instead of 50 litres of gas, I have to put between half or one tonne of lithium-ion batteries and this is the limitation.”
This means that instead of taking a few minutes to charge a car, it requires at least 30 – 40 minutes. Pellegrini states that getting beyond this limitation is a crucial step forward.
What changes need to be made?
Working alongside the Graphene Flagship, Pellegrini has said the aim is to remove the graphite from the lithium-ion batteries as it is one of the main limitations to the capacity of the lithium-ion battery.
Initially the graphite was to be replaced by silicon, which is 10x better than graphite. However, it will only offer a few cycles before it becomes unstable.
To combat this instability, the team added a small amount of protein to the silicon.
“You can make a lithium-ion battery today with silicone which is much better than conventional lithium-ion batteries, but it can only be cycled a few times because over time it [becomes unstable].
“By adding a small amount of protein, we can make silicon stable. We are developing a new material for lithium-ion batteries, which combines silica and [a] small amount of graphene – so it is a graphene silicon composite.
“By adding a small amount of graphene, the team are able to make silicon 60% more stable compared to a conventional battery without using graphene.
“[With graphene] We can make a material that’s stable and way better than graphite.
“We believe this a breakthrough in technological improvement in the field of electrical mobility in general.”