A proof-of-concept of Na-N2 rechargeable battery

Developing a rechargeable metal-nitrogen battery is desirable for energy conversion and nitrogen fixation as well as an alternative route for a potential and mild ammonia synthesis . Herein, we realized a proof-of-concept for sodium-nitrogen (Na-N 2 ) rechargeable batteries by introducing the alpha-MnO 2 (α-MnO 2 ) nanowire as a catalyst. In addition, we have also demonstrated a reversible reaction of 6Na + N 2. ↔ 2Na 3 N. This system reveals an outstanding reversible capacity of 600 mAh g −1 at 50 mAg −1 , runs ∼80 cycles with a controlled capacity of 400 mAh g −1 at discharge terminal voltage below 1.6 V and achieves a high actual specific energy density based on total active materials (about 4900 Wh/Kg MnO2 ) at the current density of 100 mAg −1 . In addition, a good efficiency of nitrogen fixation (∼26%) has been achieved. These attractive performances are mainly associated with the distinctive channel structure, high conductivity, and outstanding catalytic activity in terms of in-situ environmental transmission electron microscopy investigations. The success of Na-N 2 batteries not only provides an alternative strategy for the next-generation of electrochemical energy-storage devices, but also builds a new trajectory toward green recycling and utilization of N 2 .