I had a chicken that looked very much as yours. It was a black australorp. It was a low budget chicken purchase , so I probably had a mutt.
Maybe someone else can Identify it as something different.
Your hen does not have a single comb so it's not a Black Australorp. It also appears to have (unless it's a trick of the light) a few copper or reddish brown colored feathers in the neck area). It looks to me to be a mixed breed; possibly a Black Sex Link.