  Let $F$ be a field of characteristic zero and let $E$ be the Grassmann
algebra of an infinite dimensional $F$-vector space $L$. In this paper we study
the superalgebra structures (that is the $\mathbb{Z}_{2}$-gradings) that the
algebra $E$ admits. By using the duality between superalgebras and
automorphisms of order $2$ we prove that in many cases the
$\mathbb{Z}_{2}$-graded polynomial identities for such structures coincide with
the $\mathbb{Z}_{2}$-graded polynomial identities of the "typical" cases
$E_{\infty}$, $E_{k^\ast}$ and $E_{k}$ where the vector space $L$ is
homogeneous. Recall that these cases were completely described by Di Vincenzo
and Da Silva in \cite{disil}. Moreover we exhibit a wide range of
non-homogeneous $\mathbb{Z}_{2}$-gradings on $E$ that are
$\mathbb{Z}_{2}$-isomorphic to $E_{\infty}$, $E_{k^\ast}$ and $E_{k}$. In
particular we construct a $\mathbb{Z}_{2}$-grading on $E$ with only one
homogeneous generator in $L$ which is $\mathbb{Z}_{2}$-isomorphic to the
natural $\mathbb{Z}_{2}$-grading on $E$, here denoted by $E_{can}$.
