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Kaiyang Zeng1 Shan Yang1 Zhongting Wang1

1, National University of Singapore, Singapore, , Singapore

This talk will present the results of in-situ characterization of cathode materials for Li-ion battery by using various Scanning Probe Microscopy based techniques, including DART and Band Excitation Electrochemical Strain Microscopy (DART/BE-ESM), Biased AFM and bimodal Dual AC imaging techniques. In these SPM techniques, DART/BE-ESM allows the high frequency periodic bias to be applied on the sample surface of the electrochemically active materials. The bias will induce the local periodic oscillatory displacement caused by the Li-ions redistribution within the material, and the surface deformation caused by the Li-ion re-distribution is measured and defined as electrochemical strain. Biased AFM can apply a positive or negative point DC bias in contact mode, and hence to study the influences of positive and negative biases on the surface deformation of the cathode materials. This process can be used to study the effects of charging and discharging processes to the cathode materials. Finally, bimodal Dual AC Imaging technique is used to study the composition and properties (elasticity) changes due to the Li-ions redistribution under the electrical field. With the capability of the in-situ characterization at the nano- to micro-scale of the topography, surface deformation (electrochemical strain), ionic movement as well as the corresponding changes of the composition and properties in the cathode materials, including thin film cathodes and nanoparticles for cathode materials, this work will provide the fundamental understanding of the structure-property-functionality relationships at the nano- to micro-scales for the cathode materials used for Li-ion rechargeable batteries.

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