“We’ve all heard terrifying stories in the press and online about laptops, mobile phones, music players and other devices suddenly overheating and catching fire with no warning.
This has been worrying not just for users but for manufacturers too and only last year Packard Bell recalled a number of laptops over concerns about batteries.
The devices that caught fire were all using lithium batteries and until now no one has really understood why these batteries should rapidly overheat and catch fire. Now scientists from Cambridge University in the UK believe they have discovered a way to find out exactly what’s going on.
It’s all to do with the growth of metal fibres in the batteries. These fibres are known as dendrites and when lithium batteries are charged up quickly or repeatedly, tiny lithium dendrites form on the carbon anodes causing short circuits which in turn cause the device to rapidly overheat and catch fire.
The researchers at Cambridge used Nuclear Magnetic Resonance Spectroscopy (NMR), which is normally used to identify elements in molecules, to actually “see” how the dendrites form inside the battery.
Up till now scientists have had to rely on theoretical models and optical and scanning electron microscopes to study how dendrites form but with NMR they can actually look inside the battery and watch what changes are taking place as they are happening and whilst the battery is in operation.
A better understanding of why these dendrites form and under what conditions and most importantly, how to stop them, would allow battery manufacturers to improve the safety and the efficiency of the batteries.
Professor Clare Grey of Cambridge University’s Chemistry Department said in the Journal of Nature Studies:
“These dead lithium fibres have been a significant impediment to the commercialisation of new generations of higher capacity batteries
“Fire safety must be solved before we can get to the next generation of lithium-ion batteries and before we can safely use these batteries in a wider range of transport applications.
“Now that we can monitor dendrite formation inside batteries, we can identify when they are formed and under what conditions.
“Our new method should allow researchers to identify which conditions lead to dendrite formation and to rapidly screen potential fixes to prevent the problem.”
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