‘We got (a) surprise that it was not working as well as lithium-ion, but (in fact) a bit better than lithium-ion,’ Dr Aucher said. Much of the LISA work is building on the findings of a project called ALISE, which was led by Dr Christophe Aucher, Leitat’s principal researcher in energy storage.ĭr Aucher says a notable outcome from ALISE was that carmaker SEAT showed that Li-S technology offered 10% better driving range than lithium-ion technology for a plug-in-hybrid electric vehicle (PHEV) and about 2% better for a battery electric vehicle (BEV) – from a battery pack about 15% lighter than the equivalent. ‘Even if we don’t have a final product (for passenger vehicles), for sure we’re going to have some results that can improve lithium-sulphur batteries,’ he said. The idea is to enclose a material that has a heat-sensitive cut-off, behaving essentially like a trip-switch that stops the electrical flows if the temperature rises too sharply.ĭr Santos is confident that the LISA project will result in substantial improvements to the technology. They are currently experimenting with a combination of solid ceramic elements and an adaptable, flexible polymer.Īnother approach is to incorporate a ‘chemical fuse’ into the cell. So the LISA consortium is working on an electrolyte that minimises that risk. One of the steps the LISA researchers are taking is working towards a solid electrolyte – the material that conducts ions (charged atoms and molecules) conducting material between the positive and negative terminals inside the battery.Ĭonventional lithium-ion batteries generally use an electrolytic gel or liquid, but these can pose a fire risk, even at low temperatures. ‘For mass integration (in passenger cars), we are talking about (something like) 10 years from now.’ Dr Christophe Aucher, Leitat, Barcelona, Spain While Li-S cells store can theoretically store up to five times the energy of Li-ion batteries by mass, they also take up more volume, so the researchers are focused on ensuring solutions are as compact as possible.
And the LISA partners are working on various options for each. The components of the lithium-sulphur cell all need optimising – from the anode and its protective ceramic layer, the membrane, the electrolyte and the cathode. ‘We have very good partners working hard and we could have very good results very soon.’ ‘I am very confident about the anode,’ Dr Santos said. This protects the lithium anode from degrading and prevents the growth of the unruly dendrite spikes. To do that, LISA consortium partner Pulsedeon, of Tampere in Finland, uses lasers to deposit ceramic composite on the anode in layers just a few microns thick. He is the technical coordinator of the LISA project, which is working to optimise the various elements of lithium-sulphur batteries to make them compact enough – and reliable enough – to be used in small electric cars.Ī primary goal is to preserve the lithium anode for many more recharging cycles. So they need substantial improvement to become commercially viable in passenger cars – a prime target market, says Dr Luis Santos, an energy storage researcher at Leitat technical institute in Barcelona, Spain. This is well-documented problem that can afflict Li-ion batteries, which is why airline safety requires backup power packs for mobile phones to be carried only in hand luggage, where smoke or a fire is more likely to be noticed or detected.īattery cell developers have had difficulty getting the lithium to re-deposit smoothly and evenly back on the anode while recharging lithium-sulphur batteries, rather than in the ragged spikes.Ĭurrent lithium-sulphur batteries may work for perhaps as few as 50 recharging cycles.
That reduces the power the battery can deliver and can also end up making a short-circuit, potentially causing a flammable electrolyte to catch fire. The deposits degrade the anode and the electrolyte, which is the medium in which lithium ions shuttle back and forth. The deposits form in thin, tree-like structures called dendrites, which branch up from the lithium anode – the negative electrode inside the battery. It is all in the internal chemistry: charging a Li-S battery causes a build-up of chemical deposits that degrade the cell and shorten its lifespan. The main problem is that current lithium-sulphur (Li-S) batteries cannot be recharged enough times before they fail to make them commercially viable.
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