Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise t...Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise tailoring of the electronic structure for optimizing the Na+intercalation behavior,yet is greatly challenging.Herein,Fe-N-C graphitic layer-encapsulating Fe3C species within hard carbon nanosheets(Fe-N-C/Fe3C@HCNs)are rationally engineered by pyrolysis of self-assembled polymer.Impressively,the Fe-N-C/Fe3C@HCNs exhibit outstanding rate capacity(242 mAh·g^(−1)at 2,000 mA·g^(−1)),which is 2.1 and 4.2 times higher than that of Fe-N-C and N-doped carbon(N-C),respectively,and prolonged cycling stability(176 mAh·g^(−1)at 2,000 mA·g^(−1)after 2,000 cycles).Theoretical calculations unveil that the Fe3C species enhance the electronic transfer from Na to Fe-N-C,resulting in the charge redistribution between the interfaces of Fe3C and Fe-N-C.Thus,the optimized adsorption behavior towards Na+reduces the thermodynamic energy barriers.The synergistic effect of Fe3C and Fe-N-C species maintains the structural integrity of electrode materials during the sodiation/desodiation process.The in-depth insight into the advanced Na+storage mechanisms of Fe3C@Fe-N-C offers precise guidance for the rational establishment of confinement heterostructures in SIBs.展开更多
基金the National Key R&D Program of China(Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China(Nos.21890753,21988101,22162026,and 21875221)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB36030200)the Danish company Haldor Topsøe A/S,the Youth Talent Support Program of High-Level Talents Special Support Plan in Henan Province(No.ZYQR201810148)Creative talents in the Education Department of Henan Province(No.19HASTIT039).
文摘Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise tailoring of the electronic structure for optimizing the Na+intercalation behavior,yet is greatly challenging.Herein,Fe-N-C graphitic layer-encapsulating Fe3C species within hard carbon nanosheets(Fe-N-C/Fe3C@HCNs)are rationally engineered by pyrolysis of self-assembled polymer.Impressively,the Fe-N-C/Fe3C@HCNs exhibit outstanding rate capacity(242 mAh·g^(−1)at 2,000 mA·g^(−1)),which is 2.1 and 4.2 times higher than that of Fe-N-C and N-doped carbon(N-C),respectively,and prolonged cycling stability(176 mAh·g^(−1)at 2,000 mA·g^(−1)after 2,000 cycles).Theoretical calculations unveil that the Fe3C species enhance the electronic transfer from Na to Fe-N-C,resulting in the charge redistribution between the interfaces of Fe3C and Fe-N-C.Thus,the optimized adsorption behavior towards Na+reduces the thermodynamic energy barriers.The synergistic effect of Fe3C and Fe-N-C species maintains the structural integrity of electrode materials during the sodiation/desodiation process.The in-depth insight into the advanced Na+storage mechanisms of Fe3C@Fe-N-C offers precise guidance for the rational establishment of confinement heterostructures in SIBs.