What will power cell phones, laptop computers and cars in the future? Will it be advanced lithium batteries, ultracapacitors, or perhaps even hydrogen power cells? For years I believed that ultracapacitors would be the predominant energy source for cars and portable computing devices. Ultracapacitors, also called high energy capacitors or EDL capacitors, are juiced up versions of the capacitors found in normal electronics applications. They can store a large amount of power, and are expected to last many times longer than conventional batteries, and could be made at a fraction of their price as the materials involve might not be as expensive as lithium and other battery materials.
Now, however, MIT has developed a new type of lithium battery which uses carbon nanotubes for internal components of the battery, the electrodes, in order to boost the amount of energy the battery can store by several times. Electrodes made out of carbon nanotubes will allow the batteries to charge much faster as well, meaning that cars powered by such batteries could charge up in minutes at a road side dinner when a person travels across the country. In addition, these batteries might be able to provide the high rates of power discharge needed for some transportation applications.
Likely such a materials engineering approach will make lithium ion batteries much more powerful such that the amount of space they take up in a given device, such as in a car, will plummet. This is important for battery powered vehicular travel where the weight of cumbersome batteries can drag down the fuel efficiency of a car.
Will this allow lithium ion batteries to compete with ultracapacitors? While this technology looks promising, carbon nanotubes are also being investigated for their use in the production of high energy capacitors. In the end, a combination hybrid between a battery and a capacitor might be developed for use in specialized applications. For now, the development of a cheap and powerful battery, or high energy capacitor, is what is holding back the widespread roll out of electric vehicles. Though the science is rapidly advancing, it may be years before such an advanced energy storage device hits the market.