Using a lab-based imaging technique that is both simple and low-cost, researchers at the Cambridge University have developed a method that allows them to look inside lithium-ion batteries and follow lithium ions moving in real time as they charge and discharge.
“When charging, the speed depends on how fast the lithium ions can pass through the particles of active material. When discharging, the speed depends on how fast the ions are inserted at the edges. If we can control these two mechanisms, it would enable lithium-ion batteries to charge much faster.” - Dr Akshay Rao from the Cavendish Laboratory, who led the research.
Although lithium-ion batteries have a number of advantages, such as high energy densities and long lifetimes in comparison, there is also the danger that they can overheat or potentially explode, in addition to being costly to produce. So far this makes them unsuitable for widespread use in two major clean technologies: electric cars and grid-scale storage for solar power.
Using the low-cost technique, the researchers identified the speed-limiting processes which, if addressed, could enable the batteries in most smartphones and laptops to charge in as little as five minutes. This would be a huge leap in comparison to the 3-4 hour charging time we currently experience. According to the researchers, their technique will help improve existing battery materials and accelerate the development of next-generation batteries.
So how does the process work? The researchers follow the lithium ions moving in real time, using special microscopes. They observe how the individual particles of lithium cobalt oxide charge and discharge by measuring the amount of scattered light.
Alice Merryweather, a PhD student at Cambridge’s Cavendish Laboratory explains the process:
“To really study what’s happening inside a battery, you essentially have to get the microscope to do two things at once: it needs to observe batteries charging and discharging over a period of several hours, but at the same time it needs to capture very fast processes happening inside the battery.”
Faster charging times would enable higher levels of efficiency in day-to-day life, with the potential to allow us to charge our phones; rechargeable batteries and eventually even our electric cars in a much shorter time span. Further benefits and possibilities are yet to be studied, however it is certainly a step in a positive direction.