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1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 2 1 that is now accessible with time-re- solved DFXM, offering key opportunities across materials science,” the scientists say. llnl.gov. INEXPENSIVE IMAGING FOR BATTERIES Superfast battery charging in most devices could soon be possible. Researchers from the University of Cambridge, U.K., created a simple tech- nique that allows them to look inside lithium-ion batteries and follow lithium ions moving in real time as the batteries charge and discharge. The researchers identified the speed-limiting processes which, if addressed, could enable the batteries in most smartphones and lap- tops to charge in as little as fiveminutes. To improve lithium-ion batteries andhelp themcharge faster, researchers need to follow and understand the pro- cesses occurring in functioning mater- ials under realistic conditions in real time. Currently, this requires sophis- Progression of the phase boundary through the active particle during the biphasic transition, for delithiation and lithiation. The color scale represents the time at which each pixel experienced the phase boundary, as a fraction of the total duration of the biphasic transition. Black dashed circles and lines depict the progression of the phase boundary. Scale bar is 2 µm. Courtesy of Nature. ticated synchrotron x-ray or electron microscopy techniques, which are time-consuming and expensive. The Cambridge team developed an opti- cal microscopy technique called inter- ferometric scattering microscopy to observe these processes at work. Using this technique, they observed individ- ual particles of lithium cobalt oxide (LCO) charging and discharging by mea- suring the amount of scattered light and could see the LCO going through a series of phase transitions in the charge-discharge cycle. The research- ers found that the mechanism of the moving boundary is different depend- ing on whether the battery is charging or discharging. The high throughput nature of themethodology allows many particles to be sampled across the entire electrode and, moving forward, will enable further exploration of what happens when batteries fail and how to prevent it. www.cam.ac.uk .