Anchoring and catalytic insights into bilayer C₄N₃ material for lithium-selenium batteries: a first-principles study

In the present work, a theoretical design for the viability of bilayer C₄N₃ (bi-C₄N₃) as a promising host material for Li-Se battery was conducted utilizing first-principles calculations. The AA- and AB-stacking configurations of bilayer C₄N₃ can effectively inhibit the shuttling of high-order polyselenides through the synergistic effect of physical confinement and strong Li-N bonds. Compared to conventional electrolytes, the AA- and AB-stacking bilayer C₄N₃ demonstrate enhanced adsorption capabilities for the polyselenides. The anchored structures of Se₈ or Li₂Se (n = 1, 2, 4, 6, 8) molecules within the bilayer C₄N₃ exhibit high electrical conductivities, which are beneficial for enhancing the electrochemical performance. The catalytic effects of AA- and AB-stacking bilayer C₄N₃ were investigated by the reduction of Se₈ and the energy barrier associated with the decomposition of Li₂Se. The AA- and AB-stacking bilayer C₄N₃ can significantly decrease the activation barrier and promote the decomposition of Li₂Se. The mean square displacement (MSD) curves reveal the pronounceably sluggish Li-ions diffusions in polyselenides within the AA- and AB-stacking bilayer C₄N₃, which in turn demonstrates the notable prospects in mitigating the shuttle effect.