Bifunctional MOF-Derived Carbon Photonic Crystal Architectures for Advanced Zn-Air and Li-S Batteries: Highly Exposed Graphitic Nitrogen Matters

Nitrogen-rich porous carbons (NPCs) are the leading cathode materials for next-generation Zn-air and Li-S batteries. However, most existing NPC suffers from insufficient exposure and harnessing of nitrogen-dopants (NDs), constraining the electrochemical performance. Herein, by combining silica templating with in situ texturing of metal-organic frameworks, a new bifunctional 3D nitrogen-rich carbon photonic crystal architecture of simultaneously record-high total pore volume (13.42 cm(3) g(-1)), ultralarge surface area (2546 m(2) g(-1)), and permeable hierarchical macro-meso-microporosity is designed, enabling sufficient exposure and accessibility of NDs. Thus, when used as cathode catalysts, the Zn-air battery delivers a fantastic capacity of 770 mAh g(Zn)(-1) at an unprecedentedly high rate of 120 mA cm(-2), with an ultrahigh power density of 197 mW cm(-2). When hosting 78 wt% sulfur, the Li-S battery affords a high-rate capacity of 967 mAh g(-1) at 2 C, with superb stability over 1000 cycles at 0.5 C (0.054% decay rate per cycle), comparable to the best literature value. The results prove the dominant role of highly exposed graphitic-N in boosting both cathode performances.