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.

From Materials to Cell: State-of-the-Art and Prospective Technologies for Lithium-Ion Battery Electrode Processing

“…This assumption may be valid on short time scales, but as time passes, the proclivity of active material sedimentation and agglomeration will cause the rheological properties to shift. This has inspired research into ways to increase the slurry’s LSV, which is generally a sign of slurry stability. ,, …”

“…This has inspired research into ways to increase the slurry's LSV, which is generally a sign of slurry stability. 197,266,334 In addition to slurry rheology, in-line process monitoring must also measure the coating thickness and/or mass (see section 3.3.2). Preferably, both thickness and mass would be measured because the density of the coating cannot be assumed to be constant in actuality.…”

The behavior of capillary suspensions at diverse length scales: From single capillary bridges to bulk

“…While this can be advantageous for the formation of porous supraparticles [76] or in the threedimensional printing of structured porous materials [45,[77][78][79], the changes due to evaporation should be better understood. The bridges do seem to persist for long times, even if they have a higher vapor pressure than the bulk liquid [80], leading to a reduction in cracking [81][82][83][84], but the link between the drying conditions and formulation should be better understood. Furthermore, the influence of the bridges on particle motion and segregation of small particles, for example, binder, should be explored.…”

The behavior of capillary suspensions at diverse length scales: from single capillary bridges to bulk

“…While this can be advantageous for the formation of porous supraparticles [72] or in the 3D printing of structured porous materials [44,[73][74][75], the changes due to evaporation should be better understood. The bridges do seem to persist for long times, even if they have a higher vapor pressure than the bulk liquid [76], leading to a reduction in cracking [77][78][79][80], but the link between the drying conditions and formulation should be better understood. Further, the influence of the bridges on particle motion and segregation of small particles, e.g.…”