Modeling the drying process in hard carbon electrodes based on the phase-field method

TL;DR

This paper introduces a multiphase-field simulation model to study pore emptying during electrode drying, emphasizing microstructural details and fluid dynamics to optimize drying processes in battery electrodes.

Contribution

It is the first to apply phase-field modeling to real hard carbon microstructures for drying, incorporating fluid flow, capillary effects, and wetting behavior.

Findings

Microstructural details significantly affect pore emptying.

Capillary number correlates with breakthrough time.

Surface doping can optimize drying by altering contact angles.

Abstract

The present work addresses the simulation of pore emptying during the drying of battery electrodes. For this purpose, a model based on the multiphase-field method (MPF) is used, since it is an established approach for modeling and simulating multiphysical problems. A model based on phase fields is introduced that takes into account fluid flow, capillary effects, and wetting behavior, all of which play an important role in drying. In addition, the MPF makes it possible to track the movement of the liquid-air interface without computationally expensive adaptive mesh generation. The presented model is used for the first time to investigate pore emptying in real hard carbon microstructures. For this purpose, the microstructures of real dried electrodes are used as input for the simulations. The simulations performed here demonstrate the importance of considering the resolved microstructural information compared to models that rely only on statistical geometry parameters such as pore size distributions. The influence of various parameters such as different microstructures, fluid viscosity, and the contact angle on pore emptying are investigated. In addition, this work establishes a correlation between the capillary number and the breakthrough time of the solvent as well as the height difference of the solvent front at the time of breakthrough. The results indicate that the drying process can be optimized by doping the particle surface, which changes the contact angle between the fluids and the particles.