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Uphill charge to the future

Although the beginning of Formula E’s second season is only two weeks away, manufacturers are already looking towards season 3 and the exciting changes it will bring with battery development.

The championship is playing a balancing act between keeping costs down and not wanting to hinder the advancement of forward-thinking technologies. If Formula E and the FIA decide to open-up battery technology manufacturers, this is where considerable gains and losses will be made, and the greatest impact on the series will occur. Here are five battery technologies that could find their way into Formula E and road cars alike…

  • Lithium-ion but with a twist.

    Lithium-ion is the battery chemistry most commonly found in our day-to-day lives. It is what powers our phones, laptops, and if your name happens to be Nelson Piquet Jr, your race car too. It essentially works by convincing a lithium atom to give away one of its electrons, send it around a circuit (which gives us the electricity) before being reunited with it on the other side. Though a relatively reliable form of energy storage, lithium-ion is far from perfect. Li-ion batteries can only hold so much energy per kilogram. This is what is referred to as energy density, and it is the main issue limiting the range of many electric vehicles.

    The sort of ‘bus stop’ in a battery, the anode, can only hold so many waiting lithium atoms, and these are normally made of layers of graphite. However, many researchers believe that the key to future batteries is to find new materials for the anode, meaning more lithium atoms can be stored, hence storing more energy. Two materials being heavily looked at for this purpose are Silicon and Graphene. These, either on their own or in combination with other materials, allow a far greater number of lithium atoms to be held. In fact, Tesla recently introduced some silicone to its battery packs, allowing them to up their capacity from 85kWh to 90kWh. The main issues with these materials though is that they can degrade quickly over time, deeming batteries unusable or unsafe. Silicon for example can massively expand and contract with changes in charge, causing it to crack. However scientists are starting to find ways of overcoming some of these issues.

  • Lithium-sulfur

    Another battery chemistry which is on its way is lithium-sulfur. These cells can typically have 2 – 4X the energy density of lithium-ion ones, meaning a far greater range for road cars. And the other way of looking at this is that in Formula E, it would allow the drivers to push a lot harder without worrying about depleting the battery. Despite these benefits however, lithium-sulfur batteries tend to experience higher deterioration over time compared to Li-ion. However, researchers are now close to making them as durable as Li-ion batteries, arguably meaning that the downsides of long term degradation are offset by their far greater capacity when new.

  • Supercapacitors: Not really batteries at all!

    A supercapacitor is essentially device that can be quickly charged up, can hold its charge for a long time, until it needs to release it. Similar to a battery? Well, in function kind-of, in terms of how they work, a mile off! Capacitors use static electricity as opposed to chemistry to store energy: two conducting metal plates, with a insulator in between. This allows a build up of charge on one side of the metal plates, and then when the time is right, through control of the insulator, you can release this build up of charge.

    But what makes a supercapacitor, well, super? Let’s use the analogy of water. In a regular capacitor, the metal plates are just your average kitchen cloth. When in a super capacitor, they are much more porous, large sponges. This is the field which researchers are working at the most, finding new materials to use for the plates in the supercapacitor. Recently, some Korean scientists have found a way of using a form of graphene to be able to store a far larger amount of energy than what has been previously achieved. Supercapacitors are also much more able to recharge quickly, very useful when capturing large amounts of energy under braking in a matter of seconds. However, the main drawback with supercapacitors at the moment is their low energy density compared to traditional batteries. So think of it as a dilemma like this, would you rather have a phone that you can charge in a minute but only lasts half a day, or one that takes 4 hours to charge but lasts a day and a half?

  • Flexible batteries

    At present, the Formula E battery is simply a large box sitting in the back of the car, just behind the driver. But imagine this, a Formula E car, but with every nook and cranny, from front to back, filled with batteries. LG-Chem and many other companies are making this possible, with new flexible batteries that can be molded in all different ways. This is also being made possible by some new battery chemistries which allow for cells to be made in much more intricate shapes. Volvo have even worked on car body-panels which work as batteries!

  • Modular Batteries

    You may have got the gist that different storage mechanisms have different pros and cons. But what about combining the best bits of all of them? This is where modular batteries come in. Modular batteries have a mix of different chemistry types within them, using different bits of the battery for different purposes. One of the largest scale projects using this is EON’s M5BAT. It is an energy storage system for large-scale renewable energy sources. However what makes it special is its combination of three battery types: Lithium-ion, Lead-Acid, and a third, high temperature ‘powered’ battery. Each component has it’s own role, with the Li-ion battery coping with quick surges in power demand, the Lead-Acid coping with slightly more sustained surges in power, and the high temperature battery dealing with a long term power demand, lets say if there was a power cut.

    Now by no means would the M5BAT system work in a Formula E or even a road car, but the same principles of sharing energy demands across multiple battery types could definitely work. One that could definitely benefit a Formula E car would be a supercapacitor-lithium ion modular system. The lithium-ion battery would deal with the majority of the energy requirements, such as long straights, while the supercapacitor would work well at recuperating large amounts of braking energy as well as deploying it out corners to increase acceleration.

It still isn’t clear if Formula E and the FIA will decide to go with a universal battery supplier, such as Williams Advanced Engineering or Rimac, or alternatively to allow manufacturers to innovate their own systems. But with Motomatica (technical supplier of the Trulli team) working on a graphene battery, and EV start-up NEXTEV (partners of the Team China squad) hiring from the likes of Tesla, it would seem a waste to not capitalise on this hunger for innovation. And it is this innovation that will ultimately fulfil Formula E’s founding principle, to drive the innovation of EV technologies forwards.