Binder migration during drying of lithium-ion battery electrodes: modelling and comparison to experiment

TL;DR

This paper develops a mathematical model to understand binder migration during lithium-ion battery electrode drying, showing how drying rate affects binder distribution and electrode quality, with experimental validation.

Contribution

The study introduces a new mathematical model for binder migration during electrode drying, linking drying rate to binder distribution and electrode performance.

Findings

Low drying rates produce homogeneous binder profiles.

High drying rates cause binder accumulation near evaporation surface.

Model predictions align with experimental observations.

Abstract

The drying process is a crucial step in electrode manufacture as it can affect the component distribution within the electrode. Phenomena such as binder migration can have negative effects in the form of poor cell performance (e.g. capacity fade) or mechanical failure (e.g. electrode delamination from the current collector). We present a mathematical model that tracks the evolution of the binder concentration in the electrode during drying. Solutions to the model predict that low drying rates lead to a favourable homogeneous binder profile across the electrode film, whereas high drying rates result in an unfavourable accumulation of binder near the evaporation surface. These results show strong qualitative agreement with experimental observations and provide a cogent explanation for why fast drying conditions result in poorly performing electrodes. Finally, we provide some guidelines on how the drying process could be optimised to offer relatively short drying times whilst simultaneously maintaining a roughly homogeneous binder distribution.