In the context of the energy crisis and sustainable development, the electrocatalytic nitrogen reduction reaction (NRR) for ammonia synthesis with zero-carbon emission characteristics holds great promise. Developing highly efficient electrocatalysts with high ammonia yield and Faradaic efficiency (FE) for the nitrogen reduction reaction process (NRR) is crucial for enhancing the efficiency of ammonia synthesis. The modulation of electronic structure through interface engineering and vacancy engineering is a new approach to enhance the performance of catalyst. An efficient Cu₂S@Co₃S₄/CF catalyst with core-shell heterojunction structure and sulfur vacancies was prepared, which exhibited an ammonia yield of 122 μg•h^－1•cm^－2 and a Faradaic efficiency of 34.6%, with the ammonia synthesis rate remaining consistently stable over 6 cycles of testing, outperforming most reported similar catalysts. Comprehensive experiments and characterization demonstrate that the high performance of the catalyst is attributed to the fact that the Cu₂S core donates electrons to the Co₃S₄ shell through a uniform interface, which can promote the hydrogenation reactions of NRR while retarding the coupling of *H to form byproduct hydrogen. This contribute to a more optimal balance between the rate of ammonia production and the Faraday efficiency. Additionally, the formation of abundant sulfur vacancies significantly enhances nitrogen adsorption performance in this material. Moreover, the Zn‐N₂ battery assembled with Cu₂S@Co₃S₄/CF shows an excellent power density of 14.6 mW•cm⁻², which enables the simultaneous ammonia production and energy supply. This work demonstrates a promising approach to develop highly efficient electrocatalysts for sustainable ammonia production, with significant implications for addressing the energy crisis and promoting the transition towards a low-carbon economy.