Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (7): 861-866.DOI: 10.6023/A22020088 Previous Articles     Next Articles



马行宇, 孙晖*(), 李江, 刘之洋, 周红军   

  1. 中国石油大学(北京) 新能源与材料学院 北京 102249
  • 投稿日期:2022-02-25 发布日期:2022-05-12
  • 通讯作者: 孙晖
  • 基金资助:
    国家重点研发计划(2021YFB4000405); 中石油战略合作科技专项(ZLZX2020-04)

“Continuous” Nitrogen Reduction Synthesis of Ammonia Based on Li-N2 Battery System

Xingyu Ma, Hui Sun(), Jiang Li, Zhiyang Liu, Hongjun Zhou   

  1. College of New Energy and Materials, China University of Petroleum-Beijing, Beijing 102249
  • Received:2022-02-25 Published:2022-05-12
  • Contact: Hui Sun
  • Supported by:
    National Key Research and Development Program of China(2021YFB4000405); PetroChina Strategic Cooperation Science and Technology Project(ZLZX2020-04)

The production of ammonia using the Haber Bosch process cannot meet the goal of carbon neutral in the future, electrochemical nitrogen reduction reaction (NRR) to synthesize ammonia contains many advantages and is widely studied these years. Among them, the indirect lithium-mediated nitrogen reduction (LiNR) to synthesize ammonia, which has been successfully repeated, is considered to be a feasible way to produce ammonia via electrochemical method. Li-N2 battery is another emerging direction, that reduce N2 to Li3N successfully during discharge, while received little attention. This paper, innovatively combining Li-N2 battery system and LiNR, not only utilizes the discharge reduction reaction to fix N2, but also co-reacts Li, N2 and proton source (H2O here) to produce NH3. A common discharge and charge reaction are included, constituting a complete and clear lithium cycle procedure. During the discharge process, NH3 generates continuously when N2 and H2O are fed together through the gas diffusion layer in the cathode, and the discharge potential in experiment is close to the theoretical value. When the constant current of 100 μA (0.05 mA•cm-2) is used for 2 h discharge, the ammonia production is 0.67 μg•cm-2 with Faraday efficiency of 3.2%. A contrast experiment shows that NH3 generates only when N2 and H2O react together. Possible secondary reactions or reasons during discharging and mechanisms for ammonia production during charging are discussed. Lithium can be recycled between cathode and anode, based on Li-N2 battery, by the recommended procedure, while NH3 is produced every cycle and goes on. Cyclic ammonia production experiment demonstrates that the yield increases with the number of cycles almost linearly in 3 cycles. Finally, the discharge product LiOH is detected on the cathode inner surface, which proves that the discharge reaction proposed in this paper is valid. For the development of new types of nitrogen fixation methods, this scheme has great research and utilization spaces.

Key words: electrochemistry, nitrogen fixation, synthesis of ammonia, Li-N2 battery, metallic lithium