Ceramic Coated Plastic Separators (CCS) with Chemically Modified Nano-Boehmite Particles

摘要

The great majority of today's ceramic coated plastic separators (CCS) use ceramic particles of a micron size around 0.5 to 1.0 microns in diameter. These ceramic particles are typically either anhydrous aluminum oxide (alumina) or aluminum oxide monohydrate (boehmite) and have been widely adopted for electric vehicle batteries for their enhanced heat stability and safety. This presentation covers the advantages of using nano-boehmite particles for CCS and describes how the lower density of boehmite compared to alumina and the nano-sized particles in the range of 5 nm to 90 nm in diameter provide a much lower ceramic coat weight and coating thickness for nano-boehmite CCS compared to micro-ceramic CCS. Because the boehmite particles have many hydroxyl groups, unlike alumina, the presentation describes how various surface treatments can be chemically bonded to the boehmite particles to provide increased adhesion, cohesion, lower water content, and greater ionic conductivity in the CCS. These surface treatments include chemical reaction with organic polymers, organic sulfonic acids, and organic carbonates. It will be shown how organically-modified nano-boehmite particles can provide high heat stability of less than 5% shrinkage at 150C at less than one-half of the ceramic coat weight and the coating thickness required with commercial alumina CCS.