  We present a general formula for constructing R-matrices with non-additive
spectral parameters associated with a type-I quantum superalgebra. The spectral
parameters originate from two one-parameter families of inequivalent
finite-dimensional irreducible representations of the quantum superalgebra upon
which the R-matrix acts. Applying to the quantum superalgebra $U_q(gl(2|1))$,
we obtain the explicit expression for the $U_q(gl(2|1))$-invariant R-matrix
which is of non-difference form in spectral parameters. Using this R-matrix we
derive a new two-parameter integrable model of strongly correlated electrons
with pure imaginary pair hopping terms.
