To overcome the inherent energy-density penalty associated with conventional non-energetic fluoropolymer coatings while simultaneously enhancing the ignition performance and hydrophobicity of micron-sized aluminum powder, a novel energetic fluorine-containing compound, 1,4-dinitro-5,5-bis(trifluoromethyl)hexahydroimidazo[4,5-d]imidazole-2(1H)-one (DNG), was chemically grafted onto the aluminum surface via a Mannich reaction using γ-aminopropyltriethoxysilane (KH550) as the coupling agent. A series of Al@KH550@DNG composite particles with varying DNG contents were fabricated, and their crystal structure, surface chemical composition, microstructure, thermal decomposition behavior, ignition and combustion characteristics, and hydrophobicity were systematically investigated by XRD, FT-IR, XPS, SEM, TG-DSC, laser-ignition high-speed videography, and contact-angle measurements. The results demonstrate that DNG forms a stable, uniform molecular layer on the aluminum surface through C-N covalent bonds. At an optimal DNG mass fraction of 10 wt%, the exothermic enthalpy of the composite increases substantially from 5891.14 J·g-1 to 14835.28 J·g-1 (a 152% enhancement), the ignition delay time is shortened from 220 ms to 44.5 ms, the combustion duration is extended from 457.5 ms to 955.5 ms, and the water contact angle rises from 56.7° to 133.0°, indicating markedly improved hydrophobicity. By constructing a chemically grafted interfacial energetic fluorine-containing layer, this strategy simultaneously preserves high energy density and effectively enhances the energy release rate, ignition and combustion performance, and moisture resistance of aluminum powder, offering an innovative route for developing high-performance aluminum-based fuels for solid propellants.