The 1905 Fritchle electric car had the same 100-mile range as many of today’s EVs. Sure, it was lighter and less powerful, but the point here is we have plenty of room for improvement and batteries are where the opportunity exists. This is mostly because we have such high safety, speed and carrying capacity requirements that are inflexible. Many wonder if a breakthrough battery technology will ever come for the emerging electric vehicle market or if the future lies in capacitors.
Capacitors
Going into the future, Tesla’s CEO Elon Musk believes capacitors will be the technology of choice for electric vehicles. Capacitors can store and release electrical energy much faster than batteries and fuel cells — charging in approximately 1 – 10 seconds as opposed to 10 – 60 minutes for typical lithium-ion batteries — and can be recharged millions of times. Unlike batteries that use chemical reactions to produce electricity, capacitors store energy on two electrically conductive plates (one positive, one negative charge).
Pound for pound, capacitors can’t store nearly as much energy as batteries. To solve this problem for an EV market that demands high capacity at low weight, a high power version called ultracapacitors (also known as supercapacitors or double-layer capacitors) have been gaining traction. In addition to their long lifespans, they take mere seconds to charge, have no risk of overcharging, are safe, and offer high performance at low temperatures. Aside from their lack of storage capacity, other drawbacks include a quick rate of self-discharge and high cost.
FastCAP Systems has developed an ultracapacitor that uses carbon nanotube electrode technology to boost the capacitor’s surface area and voltage, which ups its storage capacity significantly while delivering energy almost instantly, making it an ideal choice for high performance vehicles that require fast acceleration and braking. Though this emergent technology offers improved storage, it can still only deliver approximately 25% the capacity of a lithium-ion battery.
Getting around the low capacity of ultracapacitors, Sinautec Automobile Technologies have applied the technology for city buses by converting bus stops every two or three miles into charging stations. Though the regular mini-charges can cause slight inconvenience, the energy savings makes it worthwhile. According to Sinautec’s estimates, their buses can achieve lifetime fuel savings of $200,000. Ultracapacitor technology is well-suited to buses, which need to stop regularly anyways to pick up passengers. For the EV market, it remains to be seen how the technology can effectively be applied.
Batteries
Though batteries currently being used in electric vehicles leave much to be desired, recent technological advances point towards a better future. Researchers at the Massachusetts Institute of Technology (MIT) have been experimenting with semi-solid flow cells that can be recharged as quickly as it takes to pump gas. This technology differs from standard batteries because the electrodes are made up of particles suspended in liquid electrolyte. Researchers claim that this new technology will cut the size and cost of a battery by half, potentially giving battery-powered vehicles the needed boost for them to compete with gas-powered cars.
MIT has also developed a fast-charging battery that uses lithium iron phosphate for its electrode material. The battery boasts a 10-20 second discharge rate, which is comparable to ultracapacitors, but with the high energy capacity of standard lithium-ion. In addition to its fast charge rate and high capacity, this material does not degrade as much as other batteries, resulting in less need for material, cutting down on cost, size, and weight.
Lithium-air is another emergent technology that puts a spin on the typical battery. In this technology the lithium anode is coupled with an air cathode through atmospheric oxygen. With an unlimited supply of oxygen, this battery’s performance is only restricted by its lithium anode, resulting in a high capacity.
Emerging ultracapacitor and battery technologies both have the potential to score a big win for the EV market. The challenge with all these wonderful technological advances lies in commercializing them. It’s one thing to develop a great technology, but quite another to overcome the many performance, material accessibility, and safety obstacles that impede deployment on a commercial scale. When a technology emerges that has a high storage capacity, fast recharge rate, low weight and cost, but can also overcome obstacles to commercial application, it’ll be fair to say that the race to power the vehicles of the future has been won.
