A Batanin $\omega$-category is a weak ∞-category? defined as an algebra over a suitable contractible globular operad. So this is an algebraic definition of higher category.
The definition is similar to that of Trimble n-category (which is actually a special case of a Batanin $\omega$-category) and similar to the definition of Grothendieck-Maltsiniotis infinity-category.
When a weak $\infty$-category is modeled as a module over an $O$-operad, morphisms of modules $F : C \to D$ will correspond to strict $\infty$ functors. To get weak $\infty$-functors one has to resolve $C$.
One way to do this is described in (Garner).
Michael Batanin, Monoidal globular categories as a natural environment for the theory of weak $n$-categories , Advances in Mathematics 136 (1998), no. 1, 39–103.
Ross Street, The role of Michael Batanin’s monoidal globular categories, in Higher Category Theory, eds. E. Getzler and M. Kapranov, Contemp. Math. 230, American Mathematial Society, Providence, Rhode Island, 1998, pp. 99–116. (pdf)
Work towards establishing the homotopy hypothesis for Batanin $\omega$-groupoids can be found here:
A nice introduction to this subject is:
A discussion of weak $\omega$-functors between Batanin $\omega$-categories is in
An application of Batanin weak $\omega$-groupoids to homotopy type theory appears in
A discussion of weak $\omega$-functors between Batanin $\omega$-categories, and all kind of weak $n$-transformations in the spirit of Batanin approach, with an emphasis to the possibility to the existence of the weak $\omega$-category of the weak $\omega$-categories in Batanin’s sense is in