Tracking Battery Dynamics by Operando Synchrotron X‑ray Imaging:Operation from Liquid Electrolytes to Solid-State Electrolytes

CONSPECTUS:Lithium-ion batteries have been widely applied in portable electronics due to their high energy density(300 Wh kg^(-1)).However,their potential applications in electric vehicles and grid energy storage call for higher energy density toward 500 Wh kg^(-1).Solid-state batteries,employing highly safe electrolytes to replace flammable liquid electrolytes,probably achieve this aim by reviving the metallic lithium anode.However,the sluggish lithium transport across the solid−solid interfaces seriously influences the actual battery electrochemistry in applications.Unlike the relatively complete basic theories of solid−liquid electrochemistry,the electrochemical fundamentals and models in the solid-state batteries are still ambiguous,which cannot give a guideline for optimizing strategies for high battery performance.Therefore,building better batteries for next-generation electrochemical energy storage remains a great challenge.Synchrotron X-ray imaging techniques are currently catching increasing attention due to their natural advantages,which are nondestructiveness,chemically responsiveness,elementally sensitivity,and high penetrability to enable operando investigation of a real battery.Based on the derived nanotomography techniques,it can provide 3D morphological information including thousands of slice morphologies from the bulk to the surface.Combined with X-ray absorption spectroscopy,X-ray imaging can even present chemical and phase mapping information,including the oxidation state,local environment,etc.,with sub-30 nm spatial resolution,which addresses the issues that we only obtain as averaged information in traditional X-ray absorption spectroscopy.Through an operando charging/discharging setup,X-ray imaging enables the study of the correlation between the morphology change and the chemical evolution(mapping)under different states of charge and cycling.In addition,X-ray imaging breaks up the size limit of nanoscale samples for the in-situ transmission electron microscope imaging,which enables a large,thick sample with a broad field of view,truly uncovering the behavior inside a real battery system.