Abstract
Porous carbon is regarded as one of the most promising anode candidates for Li-ion battery and Na-ion battery, and the specific porous structure and heteroatom doping within porous carbon play a key role in the electrochemical performance. We herein demonstrate a series of nitrogen-doped porous carbon (NPC) by simply carbonizing bimetallic ZnCo-containing zeolitic imidazolate frameworks (ZnCo-ZIFs). The nitrogen content, specific surface area, and microstructure of prepared NPCs are balanced by adjusting the Zn2+/Co2+ molar ratio of ZnCo-ZIFs and carbonization process parameters. The optimized NPC derived from ZnCo-ZIFs delivers high specific capacity of 876.5 and 352.6 mA h g−1 for Li+ storage at 0.1 and 5 A g−1, respectively. After repeating 500 cycles at a high current density of 1 A g−1, it almost has no capacity loss. In addition, the electrode also shows a great promise for Na+ storage. The excellent electrochemical Li+/Na+ storage performances could be attributed to the hierarchical porous structure, large specific surface area, and relatively high N-doping content.
Highlights
Li-ion batteries (LIBs) and Na-ion batteries (SIBs) are considered as the most promising representatives of secondary battery system, which are widely applied in smart grids, portable electronics and electrical vehicles [1, 2]
It is found that the optimized ZnCo-ZIF-derived nitrogen-doped porous carbon (NPC) shows promise for electrochemical Li+/Na+ storage, which could be attributed to the hierarchical porous structure, large specific surface area and relatively high N-doping content
A similar procedure was applied for the preparation of purple powders of ZIF-67 polyhedra, expect that Zn(CH3COO)2·2H2O was replaced by Co(CH3COO)2·4H2O
Summary
Li-ion batteries (LIBs) and Na-ion batteries (SIBs) are considered as the most promising representatives of secondary battery system, which are widely applied in smart grids, portable electronics and electrical vehicles [1, 2]. At a properly controlled carbonization temperature, NPC derived from Zn-containing ZIF-8 can basically inherit the pore structure of initial precursor, demonstrating large surface area and high N-doping content. The synthesis procedure of ZnCo-ZIF is very simple, and the Zn/Co molar ratio can be adjusted To this end, here in this work, we employ bimetallic ZnCo-ZIFs to prepare nanoporous carbon for the anodes of LIBs and SIBs. By optimizing the Zn/Co molar ratio and carbonization temperature, the resulting NPC achieves desirable properties including high surface area and favorable porous structure as well as high N-doping content, which endows with ample active sites, accessible charge transfer and ion diffusion, and exhibits excellent Li+/Na+ storage performances
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