Probing inhomogeneous rocksalt growth using structure-resolved simulations

Abstract

Ni-rich cathode materials are widely used in lithium-ion batteries due to their high energy and power density. However, the material stability severely limits their lifetime, especially when cycling to high cutoff voltages [1]. A layered-to-rocksalt transformation at the particle surface, accompanied by the loss of lattice oxygen, has been observed experimentally at low states of lithiation [1,2]. Recent experimental work revealed an inhomogeneous lithiation due to an inhomogeneity in rocksalt growth on single particles [3]. In real electrode structures, these particles are embedded in a complex electrode matrix with a concentration and potential distribution influenced by microstructural features such as particle size distribution, conductive additives or tortuosity. To investigate electrode degradation under realistic conditions, computational simulation tools can be availed. In this contribution, we present a novel modeling approach to describe oxygen release and phase reconstruction in Ni-rich cathode materials [4]. The model was first implemented in a P2D approach and further extended to our simulation framework BEST [5] for 3D microstructure-resolved simulations. By applying our modeling approach to a high-resolution FIB-SEM tomography of a commercial Ni-rich cathode [6], we demonstrate how transport processes in realistic electrodes cause inhomogeneous phase reconstruction across the electrode. We will further discuss the impact of particle size and particle position on the predicted rocksalt growth as well as inhomogeneous degradation on the particle scale that results from inhomogeneous lithiation [7]. References: [1] R. Jung et al., J. Electrochem. Soc., 164 (7), A1361- A1377 (2017) [2] S.-K. Jung et al., Adv. Energy Mater., 4,1300787 (2014) [3] Z. Lun et al., Energy Environ. Sci., 18, 4097-4107 (2025) [4] S. Both et al., Batteries & Supercaps, 8 (8), e202400802 (2025) [5] A. Latz and J. Zausch, J. Power Sources, 196, 3296-3302 (2011) [6] A. Lindner, S. Both et al., Batteries & Supercaps, 7 (12), e202400503 (2024) [7] S. Both et al., ChemRxiv, https://doi.org/10.26434/chemrxiv-2025-jjm7q (2025)