Integration of Graphene-Based Ultracapacitor Li-Ion Battery Module as an Alternative Energy Source

 

As many people in and around the nanotechnology industry know, graphene has a huge potential across many application areas. One of these is in energy, more specifically energy storage systems. Whilst there has been a lot of scientific media attention around the potential for graphene in batteries, there are other areas which often fly under the radar. These are graphene-based ultracapacitors and hybrid Li-ion-ultracapacitors.

 

There has been a lot of successful research over the last year into graphene-based ultracapacitors and their implementation into battery modules. Unlike other energy areas, there are now many graphene-based ultracapacitors on the market around the world. Given that the energy market is a difficult one to break into, this alone showcases the potential that graphene has in these application areas.

 

There are reasons why ultracapacitors, on all fronts, have been used more and more over the years. Batteries alone can only store a finite amount of energy. This is fine for many applications, but applications, such as electric vehicles, which need a much greater degree of energy storage and energy release, can’t rely on batteries alone (unless they are to be charged very often which is not practical for many vehicles). However, there has been one sticking point with ultracapacitors over the years, and that is they are usually very expensive to produce, and the energy efficiency obtained by their use is often not enough to offset the cost efficiency for many applications. Therefore, hybrid storage devices that combine the strength of lithium ion batteries with the rapid charging effects of ultracapacitors has become one option.

 

So where does graphene come in? Many ultracapacitors use activated carbon. So, from a chemical standpoint, graphene is a highly compatible material, but with the added advantage of providing much higher efficiencies. The integration of graphene-based ultracapacitors into Li-ion modules is a way of also making them lighter (as a lesser amount of materials is needed when graphene is used compared to other materials), a higher strength and durability, as well as a larger internal surface area and increased electrical conductivity—both of which improve performance.

 

Many will talk about the cost of graphene, but as many people know, the cost will be vary depending on how many layers of graphene you need. As activated carbon is used for many ultracapacitors, the use of cheaper multi-layered graphene is a feasible option. We have also seen a reduction in the price of graphene over the years, and as prices continue to fall from better optimised process, larger real-world outputs from more market demand and more competition, the future price point of graphene is likely to become a huge positive against the energy efficiency that can be obtained against other carbon-based materials.

 

Some of these devices in existence today only use graphene in a small amount (not much is required to bring about benefits) and will also incorporate other nanomaterials which have had many years of optimised production (i.e. lower costs), such as carbon nanotubes. In many cases, the graphene is mixed with activated carbon and this is a way of achieving both cost and performance efficiency, especially when cheaper multi-layer graphene is best used as an additive.

 

As far as the properties go of graphene-based ultracapacitor Li-ion battery modules that exist today, they are up to 5 times as powerful as other ultracapacitors, have charge and discharge cycle rates which are 1000 times faster than Li-ion batteries, and are often immune to swelling and heat build-up as they rely on physical processes rather than chemical reactions. This latter property also helps to improve their usable lifetime over other Li-ion systems. These graphene-based hybrid systems

also offer a way of negating the issues found with conventional ultracapacitors, such as low energy densities, and poor long-term energy storage, and is seen as a way of offering the best of both worlds.

 

As these are the specifications of the graphene-inspired modules that exist today, in essentially what is the first wave, the potential for these modules and their next generations are huge. It is also an area that has the potential to pave the way for the rapid charging and efficient discharging in electronic vehicles—one of the key challenges which is holding the EV industry back from becoming a global mass market.