Operando Imaging of energy storage devices using Bragg Coherent Diffractive Imaging.

Oleg Shpyrko
University of California, San Diego (UCSD)

Lithium ion batteries are the dominant power source for mobile devices, are increasingly used in hybrid and fully electric cars, and are promising candidates for both stationary and mobile storage in the smart electrical grid that incorporates intermittent renewable energy sources. To fulfill their powerful promise, electrodes with increased capacity, faster charge rates, and minimal capacity fade must be developed. Understanding the nanomechanics due to lithium ion movement and the resulting strain distribution at the individual particle level is a crucial step and key to achieving these ambitious goals.

Among major scientific challenges related to energy storage materials is detailed understanding of nanoscale processes involved in ionic diffusion, as well as deterioration of battery electrodes that happens over many cycles. Repeated charge and discharge cycles involving intercalation and extraction of ions can lead to inhomogeneous distribution of strain, nucleation of topological defects and structural phase transformations in the electrode, leading to degradation of battery performance.

Applying in-situ Bragg CDI we reveal three-dimensional (3D) displacement field evolution of a single nanoparticle in a coin cell battery under operando conditions during charge/discharge cycles. We also performed three-dimensional imaging of dislocation dynamics in individual battery cathode nanoparticles under operando conditions using Bragg CDI which reveal nucleation and complex dynamics of dislocation networks in energy storage materials and their influence on functionality of energy storage devices.

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