Impact of Morphology of Polycrystalline and Single Crystal Nickel Rich Cathode Particles on Performance

Abstract

High nickel cathode material (NMC 811) is great candidate for high performance batteries. It has high specific capacity and lower utilization of cobalt. The morphology of the cathode particles is studied in a comprehensive manner, from the impact of synthesis parameters on primary particle size, to experimental characterization and replicating the key morphological features in computational model to elucidate the morphological features critical to the performance. The polycrystalline micron sized secondary particle is comprised of thousands of nanometers sized primary particles. The single crystal is generally 2 to 3 microns in size. The “single crystal” cathode particle may be cluster of few single crystals. The length scales of primary and secondary particles as well as internal porosity of polycrystalline cathode particles changes the characteristic diffusion length as well as surface area available for electrochemical reaction. Similarly, for single crystal, the size and the degree of clustering changes the diffusion characteristics and surface area. These variations are reflected in specific capacities obtained at different C-rates. Gaining an in-depth understanding of correlation of morphological features to performance would be helpful in directing the synthesis process. Figure 1