This study investigates the catalytic role of in-situ formed C-N species in enhancing the decomposition kinetics of Li₂CO₃ in Li-CO₂ batteries. The research demonstrates that the composition of the solid-electrolyte interphase (SEI) can be systematically regulated by tuning electrolyte solvation structures, anion coordination, and binding free energy between Li ions and anions. The results show that increasing the content of C-N species in the SEI layer significantly improves the cycling performance of Li-CO₂ batteries. Theoretical analysis reveals that C-N species provide strong adsorption sites and promote charge transfer from the interface to CO₂²⁻ during discharge and from Li₂CO₃ to C-N species during charge, thereby building a bidirectional fast-reacting bridge for CO₂ reduction/evolution reactions. This finding enables the design of a C-N rich SEI layer via dual-salt electrolytes, improving the cycle life of Li-CO₂ batteries to twice that of traditional electrolytes. The study also highlights the importance of understanding the key roles of organic SEI components in determining reaction kinetics and reversibility of Li₂CO₃, and how this knowledge can be used to improve battery performance. The results show that the C-N species in the SEI layer can enhance the reversibility of Li₂CO₃, leading to improved cycling performance. The study also demonstrates that dual-salt electrolytes can be used to further improve cyclability by increasing the content of C-N species. The 0.25 M LiNO₃/0.75 M LiFSI cell exhibits stable cycling over 220 cycles (2200 h) with 1 V overpotential. The findings provide a deep understanding of the correlation between the organic SEI components and battery performance, offering an electrolyte design principle to overcome the critical issues facing Li-CO₂ batteries for future applications.This study investigates the catalytic role of in-situ formed C-N species in enhancing the decomposition kinetics of Li₂CO₃ in Li-CO₂ batteries. The research demonstrates that the composition of the solid-electrolyte interphase (SEI) can be systematically regulated by tuning electrolyte solvation structures, anion coordination, and binding free energy between Li ions and anions. The results show that increasing the content of C-N species in the SEI layer significantly improves the cycling performance of Li-CO₂ batteries. Theoretical analysis reveals that C-N species provide strong adsorption sites and promote charge transfer from the interface to CO₂²⁻ during discharge and from Li₂CO₃ to C-N species during charge, thereby building a bidirectional fast-reacting bridge for CO₂ reduction/evolution reactions. This finding enables the design of a C-N rich SEI layer via dual-salt electrolytes, improving the cycle life of Li-CO₂ batteries to twice that of traditional electrolytes. The study also highlights the importance of understanding the key roles of organic SEI components in determining reaction kinetics and reversibility of Li₂CO₃, and how this knowledge can be used to improve battery performance. The results show that the C-N species in the SEI layer can enhance the reversibility of Li₂CO₃, leading to improved cycling performance. The study also demonstrates that dual-salt electrolytes can be used to further improve cyclability by increasing the content of C-N species. The 0.25 M LiNO₃/0.75 M LiFSI cell exhibits stable cycling over 220 cycles (2200 h) with 1 V overpotential. The findings provide a deep understanding of the correlation between the organic SEI components and battery performance, offering an electrolyte design principle to overcome the critical issues facing Li-CO₂ batteries for future applications.