Three-Dimensional Numerical Simulations on the Effect of Particle Porosity of Lithium-Nickel–Manganese–Cobalt–Oxide on the Performance of Positive Lithium-Ion Battery Electrodes

A spatially resolved electrochemical model is applied to single porous lithium–nickel–manganese–cobalt‐oxide (NMC) particles to evaluate the effect of particle porosity on the half‐cell performance. The arrangement of the primary particles within the investigated secondary particles is computer‐generated by means of the Fibonacci lattice method and is therefore identical. By varying the thickness of the sintering bridges between the primary particles, the different particle porosities are obtained. The numerical results reveal that transport limitations decrease with increasing particle porosity. This becomes evident in lower local overpotentials and more homogeneous lithium concentrations in the solid, leading to higher utilizable capacities. To find optimum particle porosities for different load conditions, a utility value analysis of two assessment approaches is performed. The volume‐based evaluation shows that nonporous particles are most suitable for high‐energy applications ≪1 C, whereas for medium to high‐power applications (1 to 10 C), particles with porosities between 10% and 20% perform best. Interestingly, the latter show even higher utilizable energy densities compared with the nonporous and the highly porous particles. ... mehrIn contrast to that, the gravimetric results show that the electrochemical performance increases with the particle porosity. Thus, the optimum inner porosity of NMC particles depends on the desired application.