What are lithium-air batteries and how do they work?

Lithium batteries are special energy storage, with a high efficiency and a long life. Thanks to these almost unique features, lithium batteries play a major role in the electronics market. Their success will definitely continue in the future.Lithium batteries will be used for specific sectors, related to renewable energy off-grid systems, smart-city projects, and on-grid hybrid power supplies. If on the one hand, lithium batteries present many advantages, on the other hand, there are several disadvantages, such as a high accumulation of waste, that is really difficult to dispose of and an increasing impoverishment of precious metals.
To tackle these issues, the European Directive 2006/66/EC, on batteries and accumulators was introduced on 26 September 2006. According to this Directive, all member states must collect and recycle materials (batteries included), regardless of their electrochemical classification.
The purpose of this article is to look at the technology behind lithium-ion air batteries, their main applications, and future technological perspectives. (For further information on this specific European Directive, please refer to the following link: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:266:0001:0014:EN:PDF


General information on lithium-air batteries

There are four different types of lithium-air batteries, classified according to the element in which the lithium salts are diluted. They are classified according to the electrolyte:

– aqueous

– non-aqueous

– hybrid (a blend of solvents)

– solid state

The common feature of these batteries is that they all use lithium (metal) as the anode, and gaseous oxygen as the cathode, independently from the different electrolytic reaction mechanisms. To better understand this analysis, we should define the following elements:

An anode is a negative pole that injects electrons to the circuit;

A cathode is a positive pole that absorbs electrons from the circuit (the type of cell is usually named after the material with which the cathode is made of);

An electrolyte separates the anode and the cathode and represents the means of transfer of ions between the two electrodes, acting as an insulator for the electrons.

 Advantages, limitations, and applications

Oxygen is basically the key factor of lithium-air batteries. In fact, oxygen can store much more energy than any other technology. For this reason, lithium-air batteries can, at least in theory, accumulate and supply the same amount of energy generated from traditional fuel engines.
However, there is a practical limitation: the capability of storing oxygen inside the battery. Therefore, the battery’s real capacity is directly proportional to the amount of oxygen used as the cathode.
That is why, to optimize their performance, these batteries need to be constantly recharged. This limitation has encouraged to undertake new studies to find more efficient solutions. Even though lithium batteries have limitations, they are currently used for nanotechnologies and alternative energy systems.
One of the most common solutions is the use of lithium batteries combined with off-grid systems. Basically, off-grid systems are plants producing clean energy with no connections to the main power grid. The high efficiency of these batteries allows to conserve electrical energy, such as photovoltaic energy and makes it available within 24 hours.
These systems are used in camping vans, ships and aircraft (only prototypes on aircraft) to supply navigation systems and telecommunications. In remote areas, there are also off-grid systems for houses.
These systems, along with alternative energy systems (such as solar thermal, photovoltaic, wind, etc.) make these houses totally independent and with no environmental impact. (For further information on these issues please click on the following link: http://www.iflscience.com/technology/new-metal-air-battery-drives-car-1800km-without-recharge )

New perspectives

A team of researchers at Argonne National Laboratory (US Department of Energy) has announced great news and new perspectives. Basically, the researchers have designed an innovative and alternative chemical process, that allows the production of a super lithium oxide, thus improving the performance and the resistance of the accumulator.
The study was consequently confirmed through some tests carried out by the University of Illinois in Chicago (UIC), where the implementation of a new type of mass spectrometer, confirmed a higher voltage capacity and a considerable increase of the charging speed of the battery.

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