Flexible/functional porous ceramic membranes for high-performance battery separators

Abstract

There is no doubt that rechargeable lithium-ion batteries occupy predominant position as a competent power source in a wide variety of industry fields including portable electronics, electric vehicles (EVs) and grid-scale energy storage systems (ESSs). For example, spinel lithium manganese oxide (LiMn2O4, LMO) materials, which are widely used in large-scale batteries for applications in EVs and ESSs, are struggling with dissolution of Mn2+ ions at elevated temperatures. The Mn2+ dissolutiontriggered disruption/contamination of electrodes are known to provoke serious capacity fading during charge/discharge cycling. As a ceramic-driven material/architecture strategy to develop an ultimate battery separator far beyond traditional polymeric separators, we have demonstrated flexible/functional porous ceramic membranes (referred to as “2F ceramic separators”) with chemical traps for chelating heavy metal ions (here, Mn2+). The 2F ceramic separator, which was comprised of the densely-packed F-silica particles spatially besieged by the PVP/PAN nanofiber skeleton, was fabricated using the simultaneous electrospraying/electrospinning process. The superlattice crystals-mimic structural uniqueness of the close-packed ceramic particles, in combination with the well-designed electrospun nanofiber skeleton, provided remarkable advances in the thermal/dimensional tolerance, mechanical flexibility and other separator properties. Furthermore, both the F-silica particles and PVP/PAN nanofibers possessed the Mn2+-chelating ability, which served as chemical traps for Mn2+ ions during their passage through the liquid electrolyte-filled interstitial voids of the 2F ceramic separator. As a consequence, the 2F ceramic separator enabled unprecedented improvements in the high-performance lithium-ion batteries. The 2F ceramic separator will hold a great deal of promise as a chemically-active separator for high-performance batteries that are eager to adopt high-energy (but, struggling with metal dissolution) electrode materials and also open a new ceramic opportunity for next-generation multifunctional membranes that are in strong pursuit of selectivity removing heavy metal ions.