Carbon materials are favorable for supercapacitors but suffer from insufficient capacitance. Heteroatom doping, especially nitrogen (N) doping, is an effective method to significantly improve the electrochemical performance, but it is still a big challenge to achieve high active nitrogen content in carbon materials. This work successfully tuned nitrogen species and content by interaction between Si-O-Si network and aluminum oxide. Besides, the structure of carbon materials varies from a coral-like network to three-dimensional structure by adjusting the precursor composition. Oxygen (O) in oxides bonds with N in carbon materials during the reaction, which makes it difficult to escape, achieving high nitrogen content of 5.29at% at 1000 ℃. On the other hand, the interaction empowers the carbon material with large pore volume of ~1.78 cm³·g^-1 and broad pore size distribution of 0.5-60 nm. Thus, the N-rich carbon material harvests high capacitance of 302 F·g^-1 at 1 A·g^-1 and excellent rate capability of 177 F·g^-1@120 A·g^-1. This unique nitrogen fixation method is a promising strategy for preparing high performance electrode materials of supercapacitors.