  The practical applications of lithium selenium (Li-Se) batteries are impeded
primarily due to the dissolution and migration of higher order polyselenides
(Li2Sen) into the electrolyte (known as shuttle effect) and inactive deposition
of lower order polyselenides. The high electrical conductivity and mechanical
strengths of MXenes make them a suitable candidate to provide adequate
anchoring to prevent polyselenides dissolution and improved electrochemical
performance. Herein, we used density functional theory (DFT) calculations to
understand the binding mechanism of Li2Sen on graphene and surface
functionalized Ti3C2 MXenes. We used graphene as reference material to assess
Li2Sen binding strengths on functionalized Ti3C2X2 (where X = S, O, F, and Cl).
We observed that Ti3C2S2 and Ti3C2O2 exhibit superior anchoring behavior
compared to graphene, Ti3C2F2, and Ti3C2Cl2. The calculated Li2Sen adsorption
strength provided by S and O terminated Ti3C2 are stronger than the commonly
used ether-based electrolyte, which is a requisite for effective suppression of
the Li2Sen shuttling. The adsorbed Li2Sen on Ti3C2X2 and graphene retains their
structural integrity without a chemical decomposition. The density of states
(DOS) analysis exhibits that the conductive behavior of the Ti3C2X2 is
preserved even after Li2Sen adsorption, which can stimulate the electrochemical
activity of involved Li2Sen chemistry. Based on our unprecedented results,
Ti3C2S2 and Ti3C2O2 are found to exhibit superior anchoring behavior for Li2Sen
adsorption, which can be leveraged for designing effective selenium-based
cathode materials to boost the electrochemical performance of the Li-Se battery
system
