Scientists from the University of Illinois Urbana-Champaign have developed a novel electron microscopy technique that enhances the capabilities of rechargeable batteries.
The team of engineers and chemists has combined a new electron microscopy technique with data mining to visually identify areas of chemical and physical alteration that inhibit ion batteries. The breakthrough may help to pioneer advanced rechargeable batteries that will be key to facilitating the energy transition, as they are crucial in a range of technologies, such as electric vehicles.
The study, ‘Formation and impact of nanoscopic oriented phase domains in electrochemical crystalline electrodes,’ is the first to analyse altered domains inside rechargeable ion batteries at the nanoscale – a ten-fold increase in resolution compared to conventional X-ray and optical methods.
Bottlenecks of rechargeable batteries
Rechargeable batteries are becoming increasingly essential for everyday technologies, most notably for use in electric vehicles (EVs). However, to increase EV adoption, their batteries will need to not only have a competitive range but also be able to be recharged rapidly to contend with the convenience of combustion engine vehicles.
However, previous attempts to identify the failure and working mechanisms of battery materials have mainly focused on the chemical effect of charging cycles, such as how the chemical composition of battery electrodes changes.
The team’s new technique – called four-dimensional scanning transmission electron microscopy (4D-STEM) – enables the researchers to utilise a highly-focused probe to collect images of the inner workings of batteries.
Wenxiang Chen, a postdoctoral researcher and first author of the study, commented: “During the operation of rechargeable ion batteries, ions diffuse in and out of the electrodes, causing mechanical strain and sometimes cracking failures. Using the new electron microscopy method, we can capture the strain-caused nanoscale domains inside battery materials for the first time.”
Future benefits of the 4D-STEM technique
Until this study, these types of microstructural heterogeneity transformations have never been used in energy storage materials, only being analysed in ceramics and metallurgy.
Professor Jian-Min Zeo, one of the leaders of the study, said: “The 4D-STEM method is critical to map otherwise inaccessible variations of crystallinity and domain orientations inside the materials.”
The team tested their 4D-STEM observations against computational modelling to identify these variations.
Chen explained: “The combined data mining and 4D-STEM data show a pattern of nucleation, growth and coalescence process inside the batteries as the strained nanoscale domains develop. These patterns were further verified using X-ray diffraction data.”
The team is confident that their research will have significant implications for advancing rechargeable batteries.
Paul Braun, a materials science and engineering professor, Materials Research Laboratory director and co-author of the study, concluded: “The impact of this research can go beyond the multivalent ion battery system studied here. The concept, principles and the enabling characterisation framework apply to electrodes in a variety of Li-ion and post-Li-ion batteries and other electrochemical systems, including fuel cells, synaptic transistors and electrochromics.”