  We derive the universal R-matrix of the quantum-deformed enveloping algebra
of centrally extended sl(2|2) using Drinfeld's quantum double construction. We
are led to enlarging the algebra by additional generators corresponding to an
sl(2) automorphism. For this maximally extended algebra we construct a
consistent Hopf algebra structure where the extensions exhibit several uncommon
features. We determine the corresponding universal R-matrix containing some
non-standard functions. Curiously, this Hopf algebra has one extra deformation
parameter for which the R-matrix does not factorize into products of
exponentials.
