Three-Dimensional Resistivity Quantification and Visualization of Silicon-Based Composite Anode Nanostructure Via Scanning Probe Microscopy

Nanocomposite Si-graphite electrodes are a viable option for increasing the energy density and life of lithium-ion battery anodes. In comparison to model systems (e.g., Si wafer and Si thin film), Si nanoparticles, ranging in diameter from tens to hundreds of nanometers, have higher rate capacity and improved fracture toughness. 1, 2 However, characterization efforts to better understand localized degradation mechanisms and heterogeneous aging behaviors of distinct components—Si, graphite, binder, and conductive carbon—in Si-based nanocomposite anodes through cycling are hindered by the limited information that can be achieved at the nanoscale using traditional microscopy techniques. To date, high resolution, three-dimensional structural visualization of the Si-based composite electrode has relied upon techniques like X-ray nano-computed tomography 3, 4 , that provide morphological information but not electronic or chemical information. In this work, we report a novel lab-scale scanning probe microscopy-based approach to map the 3-D nanostructure of composite anodes via contrast in their components’ intrinsic electronic properties. By incorporating experimental nanoscale electronic resistivity data through interpolation, volumes can be extracted to represent distinct constituent phases of the composite electrode. This approach presents an opportunity for relatively high throughput, nanoscale characterization of composite anodes and cathodes to investigate phenomena such as particle dispersion in electrode preparation and electrode evolution through cycling. Ultimately, this technique shows future utility for the multiscale understanding of structural evolution and degradation processes within lithium-ion batteries. Figure 1: Interpolated resistivity layers captured within a Si-Carbon(C) composite electrode, processed to extract C-rich and Si-rich volumes. R. C. de Guzman, J. Yang, M. M.-C. Cheng, S. O. Salley, and K. Y. Simon Ng, Journal of Materials Science, 48 (14), 4823-4833 (2013). S.-L. Chou, J.-Z. Wang, M. Choucair, H.-K. Liu, J. A. Stride, and S.-X. Dou, Electrochemistry Communications, 12 (2), 303-306 (2010). O. O. Taiwo, M. Loveridge, S. D. Beattie, D. P. Finegan, R. Bhagat, D. J. L. Brett, and P. R. Shearing, Electrochimica Acta, 253 85-92 (2017). J. Wu, F. Ma, X. Liu, X. Fan, L. Shen, Z. Wu, X. Ding, X. Han, Y. Deng, W. Hu, and C. Zhong, Small Methods, 3 (10), (2019). Figure 1