In this paper, we provide the first all-atom molecular dynamics simulation model to study the behavior of densely grafted polyelectrolyte brushes and reveal the large confinement effect that these brushes trigger to significant reduce the mobility of water and counterions and trigger a “water-in-salt” like scenario. This is Harnoor’s 17th paper, Turash’s 2nd paper, Parth’s 10th paper, Ankit’s 3rd paper, and Yanbin’s 14th paper from the group. Congrats all !!!!