Many devices in today’s world use Lithium-ion batteries such as laptops, tablets and phones. Electric and hybrid cars also use these batteries, although they are super-sized. When they first came out the batteries were renowned for having a “memory” – as you used them they changed the amount of charge they could hold “learning” the usage patterns, to a point where they became useless until they were reconditioned.
Over the years they have improved, got smaller for mobile devices and got bigger for full electric cars like the Tesla Model S and Nissan Leaf. The technology has got better with heat exchangers being built in to the units and other ideas to keep heat down and power up.
Inside a Lithium-ion battery are electrodes, one made of carbon and one made of a heavy metal: cobalt or nickel for example. There is an electrolyte solution made with Lithium that acts as the transfer of ions between the electrodes. The ions are positively charged and there is an external link between the electrodes with negatively charged electrons. When the battery is being used, the electrons and the ions travel in the same direction thus creating a power source. The generation of power creates heat and if the battery is old or well used and the electrodes are potentially worn out, this can cause the heat to combust the container, thus causing the fires that have gained media attention – especially when a third material punctures the container!
Now the boffins are working on another solution: remove the heavy metals and use sulphur. Tests are being carried out on Lithium-Sulphur batteries which in theory are lighter, can store 4 times to the power of the old-style battery and as sulphur is cheaper and more plentiful will reduce the cost per unit.
Several different academic establishments are researching and improving the idea. Early versions had heat and safety issues with the Lithium-ion electrolyte turning into to a dendrite (similar I think to a stalactite or stalagmite) which then caused a short circuit. However, some are nearing production status and possibly be available by the end of the year! Nissan is one manufacturer that has suggested that their version will double the range of a Leaf and could triple it within a few years, thus reducing the possibility of “range anxiety” which I never really understood. People don’t have the same issue with a petrol powered car, yet that can easily run out of fuel too! Perhaps this was an early 20th Century problem too.
The new developments are good for the environment (better anyway than heavy metals) and potentially reduces the usage of Lithium. Exposure to heavy metals can cause cancer and damage to a human’s central nervous system and this could be an issue in the manufacturing process or later when the batteries are recycled. Cobalt is probably the better of the heavy metals, however it can cause skin problems and other health related issues if a lot is handled. Lithium is found in areas of the world that aren’t that friendly – Russia and Bolivia for example, so any reduction in their control of this substance is good news as well.
We are at the beginning of a new step in technology for batteries and this could flow down to consumer devices as well.
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