Adhesive and Heat Resistant Separator for Long-Term Stable Lithium Ion Batteries

Abstract

Next-generation lithium ion batteries (LIBs), the promising energy sources for an electric vehicle and grid energy storage systems, should satisfy the continuous needs for high reliability and safety for long-term high-energy-density operation. A novel separator has a functional multi layer coating on both side of PE separator. It shows superior heat resistance, high electrolyte uptake, long stable cyclability when equipped in the cell, and persistent adhesion with the electrode. Multi coating layers are composed of a 2-μm-thick Al2O3 ceramic layer that enhances mechanical strength and thermal stability of the conventional polyethylene separator, and a 1.5-μm-thick adhesive layer produced from acrylic polymer beads that combine consistently between the electrode and the separator forming electrode/separator assembly during cell operation. These multi-layer coated separators enable high capacity retention and reduce impedance build up with cycling, when used in coin or pouch cells. Fabrication of multi-coating layers by aqueous coating without organic solvents not only offers environmental benefits but is also effective in cost reduction. This approach paves the way for the separator, which has long been considered an inactive major component of LIBs, to contribute towards the energy density as an active component for obtaining longer stable cyclability.