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High energy long life rechargeable battery is considered as key enabling technology for deep de-carbonization. Energy storage in the electrochemical form is attractive because of its high efficiency and fast response time. Besides the technological importance, electrochemical devices also provide a unique platform for fundamental and applied materials research since ion movement is often accompanied by inherent complex phenomena related to phase changes, electronic structure changes. In this talk, I will discuss a few new perspectives for energy storage materials including new gas electrolytes, new Li/Na intercalation compounds and new battery architectures. I hope to demonstrate how to combine knowledge-guided synthesis/characterization and computational modeling to develop and optimize new higher energy/power density electrode and electrolytes materials for rechargeable batteries from picowatt-hour to megawatt-hour. With recent advances in characterization tools and computational methods, we are able to explore ionic mobility, charge transfer and phase transformations in electrode materials in operando, and map out the structure-properties relations in functional materials for energy storage and conversion. Scanning electron microscopy and electron energy loss spectroscopy (STEM/EELS) offers unprecedented spatial resolution, which has enabled nanoscale imaging and chemical analysis of battery materials - their surfaces, grain boundaries and phase boundaries. Combining the state-of-the-art in situ operando analytical electron microscopy with first principles (FP) computational data analysis, we reveal some insights that could not be possible to see in the past. On the other hand, coherent x-ray diffraction imaging (CXDI), a lensless form of microscopy capable of discerning electron density and strain with 10 nm resolution, can be used to map the strain evolution of a single cathode particle in a functional battery as it is cycled in-situ. By combining electron based and X-ray based novel imaging techniques, I hope to showcase the diagnostic tools developed for probing and understanding energy storage materials in operando. Last but not least, I will give an update on the Cryogenic Electron Microscopy techniques which enable to visualization of Li and Na metals and their interfaces with electrolytes at atomistic-scale.
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