Evolution of internal stress in heterogeneous electrode composite during the drying process

Abstract

The mechanical behavior of electrode composite during the drying preparation has played a crucial role in the electrochemical performance of lithium-ion batteries (LIBs). Our work aimed at developing an integrated analysis method to study the component distribution, mechanical properties, and internal stress of composite coating in the process of electrode drying. The main influence factors of drying stress were thoroughly investigated. It was found that this present model could capture not only the heterogeneity effect of inactive ingredients but also the porosity-dependent viscoelasticity of electrode composite. Meanwhile, the calculated effective modulus and stress evolution upon drying time were in acceptable accord with the experimental data. Furthermore, the rapid solidification markedly increased the drying stress in electrodes and significantly impaired the tensile strength of electrode composite due to the highly gradient distributed constituents. However, the stress level at high drying temperature could be significantly reduced by an aqueous sodium alginate binder instead of poly(vinylidene fluoride). The obtained results will be a great help in efficiently manufacturing LIB electrodes with adequate mechanical integrity.