Friday, 7 December 2012

Batteries Breakthrough

Hannah Bruce Macdonald

Having been around for 200 years, you wouldn’t think that there would be much room for improvement in the field of Batteries. However, scientists at Massachusetts Institute of Technology (MIT) have managed to outdo themselves (and Duracell) by designing a battery large enough for grid-scale storage. Currently, the National Grid is playing the balancing act between the output of their generators and the consumer demand; which is particularly difficult when maintaining an alternating current (AC) of 50 Hz. This can’t be taken lightly with the responsibility of more than a slight fluctuation in this AC can cause electronic devices to fail in power surges.

The storage of energy would ease the stresses of this supply management, but the scales of energy concerned are huge and it is not as simple as building a comedy-sized battery. A normal dry-cell battery scaled up would require the combination of thousands of individual, can-sized, cells to be linked together; a complex and expensive solution. 

Liquid metal batteries may be the answer to this. In very basic terms the battery can be explained as a sandwich of three metals, a molten-salt electrolyte with a sunk, dense positive electrode and a light, floating negative electrode. The difference between the floating and sunk metals is what causes the voltage. This design is much reduced in complexity, making it a much more feasible option. With the figure of $15 million in investments from Bill Gates, Total and others, this new battery has been described as a cheap potential. This clever battery would be capable of charging from the Grid during the night while acting as a secondary generator at peak times during the day. Terrifyingly, the demand for electricity is predicted to exceed its supply in Manhattan in less than three years. This electricity crunch could be solved by these batteries storing excess energy at low times and then releasing it again when required. These batteries also lend a hand to renewable energy sources, such as wind and solar power, which cannot be relied on for consistent 24 hour supply.

The structure of a liquid metal battery

These batteries are still in relatively early development and the company Ambri are playing their cards close to their chest while they fine-tune and scale up their batteries to protect their design. The development in this area is still open with no front runner between liquid batteries and other options such as redox flow, lithium-ion and sodium-ion batteries. There may not be enough letters in the alphabet to label these batteries, but all I know is that I wouldn’t try licking it.