Continuous melt process for fabricating ionically conductive articles

DETAILED DESCRIPTION Highly conductive compositions comprising fluorinated ionomers provide numerous advantages in use in electrochemical applications such as lithium batteries.
They are single ion conductors not susceptible to performance degrading charge polarization, exhibit high stability, and can be combined with aprotic polar solvent to provide highly conductive compositions.
It is well-recognized that continuous melt processibility of the components of a battery provides a significant reduction in manufacturing cost over processes which depend upon casting and drying of solutions and dispersions.
It is of particular benefit to be able to produce electroactive components in a single processing step rather than through numerous solvent handling steps.
However, the fluorinated ionomers known in the art, the best known of which is Nafion.
RTM.
perfluoroionomer film and resin available from DuPont, Wilmington Del.
, do not exhibit melt processibility, thus placing the fluorinated ionomers of the art at a disadvantage with respect to the alternative approaches in the art which do allow for melt processing.
The melt processable ionomers known in the art, such as cation-neutralized ethylene-methacrylic acid copolymers sold under the trade name Surlyn.
RTM.
by DuPont, Wilmington, Del.
, do not provide conductive compositions with the desirable high levels of conductivity when combined with polar solvents.
The present invention provides a process for forming conductive shaped articles, the process comprising combining a fluorinated ionomer with an aprotic polar liquid, mixing the ingredients to form a plastically formable composition, and forming the composition into a shaped article.
The process depends upon the surprising plastic formability of the composition.
The present process provides immense benefits over the art.
For the first time, a fluorinated ionomer can be processed into conductive components suitable for use in electrochemical cells in a process which does not involve forming solutions or liquid or gelled dispersions, nor liquid casting steps, nor extraction steps