Computational Investigation of a Reversible Energy Storage Medium in g-BN Decorated by Lithium.

Graphene-like materials in two dimensions hold great promise for energy storage and transformation applications owing to their distinctive features, such as lightweight composition, porous geometry, etc. Among these materials, a recently discovered unit known as g-BN has demonstrated high performance in energy storage and transformation. In our efforts to enhance its applicability in adsorbing energy gases, we propose a novel composite structure by decorating Li atoms on the surface of pristine g-BN. The electronic properties of this composite have been comprehensively investigated using a first-principles method. Our findings reveal that the added Li atoms can be securely anchored on the g-BN with an adsorption energy of -3.01 eV. Furthermore, the Li atom transfers its partial 2s electrons to the g-BN, exhibiting considerable electropositivity. These metallic sites effectively polarize the adsorbed H molecules, enhancing the mutual electrostatic interactions. Each primitive cell of Li-doped g-BN can adsorb up to 13 H molecules, resulting in a storage capacity up to 6.3 wt %. This capacity significantly surpasses the goal of 4.5 wt % set by the U.S. Department of Energy. Furthermore, the typical adsorption energy of -0.209 eV per molecule of H aligns with the energy range suitable for reversible hydrogen storage. This study underscores the potential of Li-doped g-BN for energy gas adsorption, shedding light on further advancements in this field.