Methods of making single-layer lithium ion battery separators having nanofiber and microfiber components

摘要

An insulating (nonconductive) microporous polymeric battery separator comprised of a single layer of enmeshed microfibers and nanofibers is provided. Such a separator accords the ability to attune the porosity and pore size to any desired level through a single nonwoven fabric. Through a proper selection of materials as well as production processes, the resultant battery separator exhibits isotropic strengths, low shrinkage, high wettability levels, and pore sizes related directly to layer thickness. The overall production method is highly efficient and yields a combination of polymeric nanofibers within a polymeric microfiber matrix and/or onto such a substrate through high shear processing that is cost effective as well. The separator, a battery including such a separator, the method of manufacturing such a separator, and the method of utilizing such a separator within a battery device, are all encompassed within this invention.

主权项

1. A method of forming a single layer battery separator, wherein said battery separator exhibits a maximum thickness of 250 microns, and wherein said battery separator includes a combination of microfiber and nanofiber constituents, said method comprising the steps of:
a) providing an aqueous solvent; b) introducing therein a plurality of nanofibers having an average width of less than 700 nm to form a nanofiber dispersion within an aqueous solvent; c) mixing said nanofiber dispersion under high shear conditions of at least 14.13 m/sec linear speed; d) introducing a plurality of microfibers having an average width of greater than 3000 nm to form a microfiber/nanofiber dispersion within said aqueous solvent such that said microfiber/nanofiber dispersion has a concentration of fibers solids of less than 1.0% by weight of solvent; e) introducing said dispersion of step “d” within a paper making machine; f) producing a web of microfiber/nanofiber material; and g) drying said web.