Li-Air Battery Charges New Interest
The green activists can finally catch a wink; all thanks to a few UK researchers. If you have just pictured a new form of a drug or some hypnotic mumbo-jumbo, then you are totally wrong. These researchers have bettered a technique for long-lasting, rechargeable, high-performance, high specific energy density batteries. Let me break it down to you, just so that you can understand what the excitement is all about.
You will soon be able to take an 800+ kilometer drive in your electric car, talk all week on your mobile phone without even charging and traffic that doesn’t emit any green house gases.
I bet you are all ears now. But I can’t guarantee you how soon ‘soon’ will be.
A research team, led by Prof Peter G Bruce, of the University of St. Andrews in Scotland, is steering towards a fully functional Lithium-Air battery that boasts of a chemical reaction that leaves a very narrow space for the electrode degradation and lower costs. Besides long life, this battery gives a better scope to the electric cars, which are at present limited by the relatively inefficient and costly battery technology used. Before we dive into the details, here is a brief note on batteries based on Li – don’t worry, this is neither a science class nor a history lesson.
Lithium Battery: This is a non-rechargeable primary battery where the Li metal or its compounds act as an anode. Though these have high energy density, the battery might be costlier than the equipment itself, in a few applications. High currents and at times the possibility of an explosion limit their use and can develop complications.
Lithium-ion Battery: These are a favorite first choice in the consumer electronics circle given that it is the best option for a rechargeable, portable and more durable one. They are being used even in electric cars. Anode is a layered oxide and the electrolyte is a lithium-ion complex. During the functioning, the lithium ions get deposited on the cathode. When a voltage higher than the normal battery working voltage is applied, the process is reversed. The minus point is that it lasts from a few hundreds to a few thousand cycles, making it less preferable as of now.
Lithium-Air Battery: This is not a new venture. This concept had been proposed back in the 70’s and falls under the metal-air category. The oxygen, available freely in the atmosphere, combines at the cathode with the Li ions forming lithium peroxide and lithium oxide which accumulates as the battery is discharged.
The problem is that the lithium oxide radical, an intermediate product, decomposes the electrodes rapidly. The UK researchers have used a thin gold film as an electrode and developed the mechanism to produce the intended action repeatedly without decomposition. Since oxygen is freely available in the nature, the weight of this type will be less than that of a conventional battery. The researchers are at present trying other combinations such as lithium-sulfur and lithium-seawater.
The actual reason this technology is pursued is the eye-poppingly high theoretical energy density of 12 kWh/kg. As of now, a mere 10% is realizable, and on top of that it costs you an arm and a leg to realize it, due to larger size, protection elements and set-up cost these high-end batteries need. On the bright side, with a little investment, we might as well say that this is a glimpse of the future.
26 July, 2012