Quantum mechanical investigation of polypyrrole-MXene nanocomposite as an electrode material for magnesium-ion batteries

• Mg-ion adsorption energy of −0.84 eV on MXene/PPy nanocomposite. • Mg adsorbs at 2.75 Å (MXene) and 2.83 Å (PPy) bridge sites. • Physisorption dominates via charge transfer analysis. • 0.05 eV bandgap confirms electrode potential for Mg-ion batteries. The current challenge in energy storage technologies lies in identifying efficient electrode materials for Magnesium-ion (Mg-ion) batteries, motivating the exploration of the energy storage capabilities of Polypyrrole-MXene (Ti 2 CO 2 ) nanocomposites as a potential solution to enhance battery performance. Hence, in this paper, quantum mechanical simulations were employed to examine the capability of energy storage of Polypyrrole-MXene (Ti 2 CO 2 ) filled nanocomposite. The electronic structures, adsorption energies, and adsorption site of Mg@PPy/MXene (Ti 2 CO 2 ) nanocomposite were investigated. The results reveal that Mg-ions on MXene/PPy nanocomposite have a very high adsorption energy of -0.84 eV. The distance of Mg-ion adsorption from the MXene’s surface at the bridge site is 2.75 Å. However, its distance from the PPy is considerably farther at 2.83 Å. The electron difference study, using the charge transfer analysis, revealed that physisorption is the dominating adsorption mechanism for the Mg-ion in the system. The electrode's propensity to transport electrons during the electrochemical reaction is shown by the projected density of state (PDOS), and its energy bandgap is 0.05. Consequently, the MXene (Ti 2 CO 2 ) /PPy nanocomposite might be used as an Mg-ion electrode in battery applications.