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

Abstract

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. In 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.

Influence of carbon binder domain on the performance of lithium‐ion batteries: Impact of size and fractal dimension

“…The basis for the electrochemical evaluation presented in this work is the numerical model developed by Kespe et al. [ 36 ] The model was previously used in the investigation of spatial distribution of electrical conductivity within the cathode microstructure [ 35 ] as well as in the spatially resolved numerical investigation of active material porosity [ 37 ] and roughness [ 38 ] . Two non‐overlapping domains namely the solid cathode $$\Omega _S$$ and the liquid electrolyte $$\Omega _E$$ comprise the half‐cell computational domain used by the model.…”

Morphology‐Dependent Influences on the Performance of Battery Cells with a Hierarchically Structured Positive Electrode**

“…Wu et al [5] employed a continuum model of a single secondary particle concentrating on intercalationinduced stresses. Cernak et al [6] spatially resolved the secondary particle to investigate the effect of secondary particle porosity on the cell performance. Lueth et al [7] developed a continuum cell model for electrodes which consist of secondary particles possessing a certain inner porosity due to their agglomerate character.…”

Digital‐Twin‐Driven Diagnostics of Crack Propagation in a Single LiNi0.7Mn0.15Co0.15O2 Secondary Particle during Lithium Intercalation

“…[36] Cernak et al developed a more accurate 3D-structured model of a single NMC622 particle using the Fibonacci lattice method that involves a mathematical idealization of a repeating pattern. [37] However, because these approaches do not mimic the actual shape, size, and distribution of primary and secondary particles, they are insufficient for examining their mechanical characteristics, which are crucial factors that govern the degradation of secondary-particle-type nickel-rich NMCs during electrochemical cycling.…”