Long-Life Rechargeable Zn Air Battery Based on Binary Metal Carbide Armored by Nitrogen-Doped Carbon Chao Lin Xiaopeng Li Sambhaji S. Shinde Dong-Hyung Kim Xiaokai Song Haojie Zhang Jung-Ho Lee 10.1021/acsaem.8b01865.s001 https://acs.figshare.com/articles/journal_contribution/Long-Life_Rechargeable_Zn_Air_Battery_Based_on_Binary_Metal_Carbide_Armored_by_Nitrogen-Doped_Carbon/7646993 Developing low-cost and high-performance bifunctional oxygen electrocatalysts is essential for commercial realization of regenerative fuel cells and rechargeable metal air batteries. Iron carbide (Fe<sub>3</sub>C) is an ideal electrocatalyst candidate; however, its poor oxygen evolution reaction (OER) activity and stability make it serve only as a unifunctional oxygen reduction reaction (ORR) electrocatalyst. Here, we report a robust bifunctional electrocatalyst consisting of manganese–iron binary carbide (Mn<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>C) nanoparticles armored by nitrogen-doped graphitic carbon (Mn<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>C/NC). Synthesis involved facile pyrolysis of a trimetallic (Fe, Mn, Zn) zeolitic imidazolate framework. Incorporation of Mn modulated the electronic properties of Fe<sub>3</sub>C and the surrounding carbon, enhancing ORR and OER activities. Mn<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>C, well-armored by carbon layers, displayed high resistance to oxidation and corrosion. The assembled Zn-air battery (ZAB) exhibited a large peak power density (160 mW cm<sup>–2</sup> at 250 mA cm<sup>–2</sup>) with an energy density of up to 762 mWh g<sub>Zn</sub><sup>–1</sup>, high open-circuit voltage of 1.5 V, and impressive long-term stability over 1000 cycles, indicating that Mn<sub><i>x</i></sub>Fe<sub>3–<i>x</i></sub>C is one of the most stable earth abundant (cobalt-free) bifunctional electrocatalysts for rechargeable ZABs currently available. 2019-01-16 00:00:00 Binary Metal Carbide Armored carbon layers bifunctional electrocatalyst open-circuit voltage bifunctional oxygen electrocatalysts Nitrogen-Doped Carbon zeolitic imidazolate framework regenerative fuel cells Zn-air battery OER activities ZAB 1.5 V metal air batteries Mn iron carbide Fe 3 C oxygen evolution reaction energy density Long-Life Rechargeable Zn Air Battery electrocatalyst candidate ORR 1000 cycles nitrogen-doped graphitic carbon bifunctional electrocatalysts unifunctional oxygen reduction reaction