Tailoring Li–NO Battery Functionality via NO Dissociation as a Kinetic Gatekeeper

Lithium–air batteries, despite their high theoretical energy density, are limited by functional inflexibility and high overpotentials. Here, we theoretically design an innovative hybrid Li–air battery using nitric oxide (NO) as a reactive medium. Beyond energy storage, this Li–NO battery operates in a switchable mode for either nitrogen fixation or gas purification. First-principles calculations show that this tunable functionality is governed by the barrier of NO dissociation: a high barrier (7.772 eV) on graphene enables purification, whereas an ultralow barrier (<0.1 eV) on Ti2C favors fixation. Notably, Ti2C also exhibits remarkably low overpotentials for both the NO reduction and evolution reactions (NORR/NOER, 0.252 and 0.251 eV, respectively). Electronic structure analysis reveals that the superior activity and ultralow barrier of Ti2C originate from the Ti3-site-induced weakening of the N–O bond, which facilitates direct lithiation and enhances battery performance. This work provides a theoretical framework for designing customizable batteries that couple efficient valorization of contaminants with environmental remediation.