For many years Lithium-ion (Li-ion) batteries were the only choice for users of cell phones, laptops and other electronic devices. Each Lithium-ion battery consists of two sides: the anode made of carbon, and the cathode made of metal-oxide. Charging the battery, causes lithium-ions to become positive and flow from the cathode to the anode, while an electronic circuit uses electrons to balance the charge. Discharging the battery reverses the whole process. These batteries have remained unchanged for many years.
The capacity of the battery is determined by the amount of lithium-ions that can be stored in the anode. Since anodes are currently created from carbon, the maximum capacity has been reached. Newer methods are being studied, and the most promising appears to be nanowire batteries. This research, led by Yi Cui, assistant professor, has shown that silicon has the ability to absorb ten times more energy than carbon. Unfortunately, silicon has the disadvantage of swelling dramatically when charged with energy. This creates a constant swelling and shrinking while being used. Eventually, this process causes the silicon to break.
A solution has been found by Yi Cui and his team. Making use of nanotechnology solves the problem. Creating very thin silicon wires called nanowires, turned out to be the solution. For some unknown reason, the nanowires can still expand and shrink, but they do not break like the silicon layers. Unfortunately, creating these ultra fine silicon wires are still extremely expensive. One of these wires is a thousand times thinner than a human hair. Luckily, as with all new technology, costs will drop with time.
The expected capacity of 10 times that of standard Lithium-Ion batteries have not been reached yet. So far, researchers were able to increase capacity four times. This is already excellent progress, and it shows a bright future for nanowire batteries. There is however, still one kink in the cable. The silicon wires offer a great improvement on the anode side of the battery. The cathode side still needs to be improved before the full capacity of silicon batteries can be achieved.
Those who will benefit the most are any user of an electronic device that currently uses Li-ion batteries; like iPods, laptops, cell phones, video cameras, digital cameras. The advantages do not stop with electronic devices. Especially research in electric vehicles will find great support in nanowire technology. Patents have already been filed so we ought to see improvements in battery life really soon, maybe as soon as 2012. Although there is still a long way to go and a lot of work to be done, just thinking about the possibility of running a laptop from a battery for two days makes me giddy.