Simulated annealing reconstruction and characterization of the three-dimensional microstructure of a LiCoO2 Lithium-ion battery cathode

• Simulated annealing approach is adapted for 3D reconstruction of LiCoO2 cathode.
• Real size distribution of LiCoO2 particles is applied in reconstruction process.
• Reconstructed cathode accords with real one at important statistical properties.
• Effective electrode-characterization approaches have been established.
• Extensive characterization gives important structural properties, say, tortuosity.

We adapt the simulated annealing approach for reconstruction of the 3D microstructure of a LiCoO2 cathode from a commercial Li-ion battery. The real size distribution curve of LiCoO2 particles is applied to regulate the reconstruction process. By discretizing a 40 × 40 × 40 μm cathode volume with 8,000,000 numerical cubes, the cathode involving three individual phases: 1) LiCoO2 as active material, 2) pores or electrolyte, and 3) additives (polyvinylidene fluoride + carbon black) is reconstructed. The microstructural statistical properties required in the reconstruction process are extracted from 2D focused ion beam/scanning electron microscopy images or obtained by analyzing the powder mixture used to make the cathode. Characterization of the reconstructed cathode gives important structural and transport properties including the two-point correlation functions, volume-specific surface area between phases, tortuosity and geometrical connectivity of individual phase.