Binder-free bifunctional electrocatalysts are attractive for rechargeable Zn-air batteries(ZABs)in grid-scale energy storage and flexible electronics,but suffering from the sluggish mass transport and inade-quate catalytic capability.Herein,we propose a scalable approach of in-situ engineering highly exposed Fe-N4/Cx sites on the N,S-doped porous carbon nanofiber membrane as a binder-free air electrode catalyst for ZABs.ZnS nanospheres are firstly used as integrated structure-directing agents to facilitate the elec-tronic modulation of Fe-N4/Cx sites by S doping and construct the hierarchical macro/meso/micropores at high temperature.Neither additional step for removal of ZnS nanospheres nor doping process is required,significantly simplifying the pore formation process and improving the S doping efficiency.Benefiting from the enhanced intrinsic activity of high-density Fe-N4/Cx sites(23.53 μmol g-1)and the optimized mass transport of carbon nanofibers,as-synthesized electrocatalyst shows a positive half-wave potential of 0.89 V for oxygen reduction reaction and a small overpotential of 0.47 V at 10 mA cm-2 for oxygen evolution reaction.When used as the air cathode catalyst for ZABs,it delivers a high specific capacity of 699 mAh g-1 at 5 mA cm-2,a large peak power density of 228 mW cm-2 and a prolonged cycling over 1000 h.At 10 mA cm-2,a robust structure with atomically dispersed Fe is also remained after cycling for 420 h.Due to the flexible properties of the electrocatalyst,as-assembled quasi-solid-state ZAB shows stable cycling over 90 h at alternately flat/bent states,demonstrating great prospects in flexible electronic device applications.

Leping Yang;Lingxiao Yu;Zheng-Hong Huang;Feiyu Kang;Ruitao Lv

State Key Laboratory of New Ceramics and Fine Processing,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Key Laboratory of Advanced Materials(MOE),School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Institute of Materials Research,Tsinghua Shenzhen International Graduate School,Tsinghua University,Shenzhen 518055,Guangdong,China

能源化学

[1]Leping Yang;Lingxiao Yu;Zheng-Hong Huang;Feiyu Kang;Ruitao Lv-.ZnS-assisted evolution of N,S-doped hierarchical porous carbon nanofiber membrane with highly exposed Fe-N4/Cx sites for rechargeable Zn-air battery)[J].能源化学,2022(12):430-440

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