Controlling Drying Stress and Mechanical Properties of Battery Electrodes Using a Capillary Force-Induced Suspension System

Abstract

Capillary suspension processing, which uses a ternary system consisting of solid/fluid/fluid, has recently been proposed as a method for manufacturing Li-ion battery electrodes to enhance the coating performance and the adhesion of the electrodes. In this paper, we apply the concept of capillary suspension to the battery slurry and control the drying characteristics and mechanical stability. The network structure formed inside the slurry using the capillary suspension processing can be confirmed by the rheological properties and cryo-scanning electron microcopy (cryo-SEM) images. It is found that the pendular bridges of the secondary fluid restrict the rearrangement of particles during drying and thus lower the residual stress of the electrodes as evidenced by drying stress and Fourier transform infrared (FT-IR). Due to the reduction in residual stress and porous structural features, the capillary suspension-based electrodes are more sustainable to severe deformation such as repetitive bending. This paper proposes a method that can dramatically enhance the mechanical stability of electrodes that could possibly be applied to next-generation battery technology such as flexible or thick electrodes.