Transport limitations in single-crystal NCM cathode electrodes

Single-crystal LiNi 1 − y − z Co z Mn y O 2 (SC-NCM) materials are emerging as promising alternatives to polycrystalline NCMs by addressing intergranular cracking and suppressing structural degradation associated with phase transitions. However, their inherently large particle size and anisotropic morphology lead to sluggish solid-state lithium-ion transport, resulting in diffusion limitations during electrochemical cycling. To optimise SC-NCM electrodes for enhanced energy and power performance, a comprehensive understanding of how electrode level parameters, such as thickness, porosity, and active material volume fraction, influence transport properties is necessary. In this study, commercial-grade SC-NCM electrodes with areal capacities of 2 and 4 mA h cm -2 were examined using a suite of electrochemical and physicochemical techniques. Electronic, kinetic, and ionic transport limitations were identified in the 4 mA h cm -2 electrode designed for high-energy applications. Experimental data were used to parameterise and validate a physics-based half-cell model in PyBaMM, which was subsequently employed in PyBOP for numerical optimisation. By tuning key design parameters, including electrode thickness and active material volume fraction, the optimised design is predicted to deliver a 23% increase in areal 1C-discharge capacity (reaching 4.07 mAh cm −2 ). This integrated approach combining modelling and experimental validation provides a pathway for optimisation of SC-NCM electrode architectures to improve energy and power metrics in lithium-ion batteries. • Transport and kinetic limits identified in single-crystal NCM920305 electrodes. • Physics-based half-cell model developed and validated for optimisation. • Model predicts 23% higher areal capacity for 70 μ m thick electrodes. • Open-source model and data provided to support community development.