A new lab-based technique could potentially help charge the batteries in smartphones and laptops in mere minutes.
The new method, developed by researchers at the University of Cambridge (Cambridge, UK), looks inside lithium-ion batteries using interferometric scattering microscopy, which can detect and image a subwavelength object by interfering the light scattered by it with a reference light field. This allowed them to observe the innerworkings of lithium ions and track them in real time as they charged and discharged.1
The team was able to examine individual particles of lithium cobalt oxide (LCO) by measuring the amount of scattered light. The new technique’s microscope needed to observe the process over a period of several hours, while simultaneously ensuring the capture of very fast processes that were happening inside the battery.
“To make better batteries out of new materials, and to improve the batteries we’re already using, we need to understand what's going on inside them," says study co-author Dr. Christoph Schnedermann, of Cambridge’s Cavendish Laboratory.
According to the researchers, LCO passing through a series of phase transitions in the charge-discharge cycle were visible with the microscopy technique: “The phase boundaries within the LCO particles move and change as lithium ions go in and out.” The team discovered that how the boundary moves is different based on whether the battery is charging or discharging.
"When charging, the speed depends on how fast the lithium-ions can pass through the particles of active material,” says Dr. Akshay Rao, of the Cavendish Laboratory Department of Physics, who led the research. “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."
The new technique has essentially helped the researchers identify the speed-limiting processes—overturning that, the study notes, “could enable the batteries in most smartphones and laptops to charge in as little as five minutes.”
Currently, synchrotron x-ray and electron microscopy techniques are used to understand and thus enhance lithium-ion batteries. And while those batteries tout high energy and long lifetimes, they are expensive to produce, which the researchers say make them “unsuitable for widespread use in two major clean technologies: electric cars and grid-scale storage for solar power.”
This new method can “not only help improve existing battery materials but could accelerate the development of next-generation batteries,” and scale such technological hurdles that a fossil fuel-free world faces.
REFERENCE
1. A. J. Merryweather, C. Schnedermann, Q. Jacquet, C. P. Grey, and A. Rao, Nature, 594, 522–528 (2021); https://doi.org/10.1038/s41586-021-03584-2.
