Abstract: The performance of hexagonal boron nitride and graphene heterojunctions (hBN/Graphene) as anode materials for lithium–ion batteries was systematically studied using first–principles methods. The most stable heterojunction stacking structure was identified based on maximum binding energy. Lithium adsorption energies were calculated at high–symmetry sites on the outer surfaces of both materials and at the interlayer interface. Density of states calculations showed a non–zero density at the Fermi level for both pristine and lithium–adsorbed heterojunctions, indicating good electrical conductivity. The LST–QST method was used to calculate lithium diffusion barriers between adsorption sites, revealing that lower energy barriers and shorter paths enable efficient lithium migration, which can improve battery charge–discharge capacity. Open–circuit voltage and theoretical specific capacity were calculated as lithium atoms were sequentially added by layer. With three lithium layers adsorbed, the open–circuit voltage is 1.18 V and the theoretical specific capacity is 1154 mAh/g, demonstrating great potential for high theoretical capacity. These findings indicate that hBN/Graphene heterojunctions are promising candidates for high–performance lithium–ion battery anodes.