Author Manuscript Title: Na-doped C70 fullerenes/N-doped graphene/Fe-based quantum dots nano- composites for sodium-ion batteries with ultra-high coulombic efficiency Authors: Chunlian Wang; Yang Zhang; Wen He; Xudong Zhang; Zhaoyang Wang; Guihua Yang; Manman Ren; Lianzhou Wang This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofrea- ding process, which may lead to differences between this version and the Version of Record. To be cited as: ChemElectroChem 10.1002/celc.201700899 Link to VoR: https://doi.org/10.1002/celc.201700899 ARTICLE 1 Na-doped C70 fullerenes/N-doped graphene/Fe-based quantum dots nanocomposites 2 for sodium-ion batteries with ultra-high coulombic efficiency 3 Chunlian Wang,[a] Yang Zhang,[b] Wen He,*[ad] Xudong Zhang,*[a] Guihua Yang,[c] Zhaoyang Wang,[a] Manman Ren,[ad] 4 Lianzhou Wang[d] 5 [5-8] 6 Abstract: We fabricate Na-doped C70 fullerenes (Na-C70)/N-doped39 better performance. Carbon materials showing potential using 7 graphene (N-GN)/Fe-based nanocomposites (Na-C70/N-GN/FBNCs)40 in other area, such as carbon silicon composites for 8 with the multiple morphologies via an in situ one step method used41 electromagnetic materials[9], poly/multi-walled carbon nanotubes 9 the multifunction sodium lignosulfonate (SLS) as the structural42 with conductive segregated structure[10], graphene quantum dots 10 template and the main raw material. Fe-based nanoparticles can43 decorated oxide as solar cells[11]. Nanocarbon materials are 11 embed in ordered mesoporous hybrid carbon structure of Na-C7044 recognized as the leading electrode material for commercial 12 and N-GN via spontancous chelation reaction of SLS with iron ions45 LIBs anodes because of their high electrical conductivity, low 13 and carbonization under relatively mild hydrothermal treatment. We46 cost, and high chemical stability. However, these carbon-based 14 investigate the influences of molar ratio of SLS:Fe on the structure,47 anode materials used in LIBs cannot be used in SIBs because 15 component and electrochemical properties of the nanocomposites.48 the pure graphite anode only has a low capacity of 35 mAh g- 16 Its unique hybrid carbon structure offers metallicity and49 1.[12,13] The hard carbon (so-called nongraphitizable carbon) 17 superconductivity, countless bonding sites of Na ions, and facilitate50 anode can deliver a capacity of 300 mAh g-1 due to the 18 the transfer of electrons and Na ions during prolonged cycling. The 51 difference of lithium and sodium between molecular radius, but 19 nanocomposites for sodium-ion batteries (SIBs) anodes can achieve 52 its electrical conductivity and rate performance is poor.[14] 20 the highest discharge capacities of 1898 mAh g-1 at the current -1 53 To develop high performance anode materials for SIBs, Fe- 21 density of 1000 mA g , and retain a reversible capacity of 238 mAh [15] [16-18] [19] -1 54 based materials, such as FeNb11O29 , Fe2O3 , Fe3O4 , 22 g after 100 cycles, which are dramatically better than that of lithium- [20-23] [24] [25] -551 FeS , and FeS , and Fe S , have been extensively 23 ion batteries (LIBs). The discharge and charge capacity at 1 A g 2 1-x -1 56 studied because of their high theoretical capacities, low cost, 24 after 30th cycles are 356 and 119 mAh g , respectively, with the 25 ultra-high coulombic efficiency of 299% and the highest coulombic57 earth-abundance and nontoxicity. Among them, Fe2O3 and FeS2 26 efficiencies of 463% after 220 cycles. 58 have been considered as promising candidates for SIBs. 59 However, pure Fe-based electrodes in SIBs showed low 60 reversible capacities, poor cycle life and rate performance, 61 owing to low electrical conductivity, larger Na-ion radius, slower 27 Introduction 62 reaction kinetics, and huge volume expansion from Na-ion 63 insertion. The overall electrochemical performances of the pure 28 Designing and fabricating low-cost nanocomposites are64 Fe-based electrodes are still far from practical application. To 29 considerable interests in improving and optimizing65 mitigate these problems, Fe-based carbon and graphene electrochemical performances of energy storage and conversion 30 66 nanocomposites with various structures have also been studied 31 electrodes. In recent years, great efforts have been devoted to67 for Na-ion storage. [16-18,23] Inclusion of carbon coating materials 32 the research of sodium-ion batteries (SIBs) to obtain low cost,68 improves the structural stability of these Fe-based composites 33 high capacity, and long cycling life batteries and meet the69 during cycling and augments the conductivity of the active 34 demands of different fields, such as sensor, controller and power70 materials. Jun Chen et al. [16] synthesized three-dimensional 35 source.[1-4] The research on the electrode materials of SIBs has 71 (3D) porous γ-Fe2O3@C nanocomposite by using an aerosol 36 made important progress, in part because developments in 72 spray pyrolysis technology, in the nanocomposite the γ-Fe2O3 37 nanocomposite materials are making it possible to achieve 73 nanoparticles (5 nm) uniformly embedded in a porous carbon 74 matrix, which shows high-rate capability and long-term cyclability 75 when applied as an anode material for SIBs. Yiben Shao et al. [24] [a] C-L Wang, Prof. W. He, Prof. X-D Zhang, Z-Y Wang,Prof. M-M Ren 76 prepared FeS2 quantum-dots/functionalized graphene-sheet College of Material Science and Engineering, Qilu University of 77 (QDs/FGS) composites by a facile and scalable method, which Technology, Jinan 250353, China 78 were used as anode materials for sodium-ion batteries and E-mail: [email protected]; [email protected] -1 [b] Dr.Y. Zhang 79 achieved large specific discharge capacities of 742 mAh g at -1 school of information science and technology, Tsinghua university, 80 the current density of 0.5 A g in the first cycle, retained a Beijing, 100084, China 81 reversible charge capacity of 552 mAh g-1 after 100 cycles and [c] Prof. G-H Yang 82 displayed a high specific capacity of 315 mAh g-1 at the high Key Laboratory of Pulp and Paper Science and Technology of -1 Ministry of Education, Qilu University of Technology, Jinan 250353, 83 current densities of 5 A g . These results indicate that the Fe- China 84 based carbon and graphene nanocomposites can significantly [d] Prof. L-Z Wang 85 enhance cycle performance and high rate capability. But the Nanomaterials Centre, School of Chemical Engineering and AIBN, The University of Queensland,Brisbane, QLD 4072, Australia 86 synthesis of these nanocomposites is complex, high cost and 87 low productivity, which severely limits its practical application. Supporting information for this article is given via a link at the end of the document. 88 Besides, as iron exists in different stoichiometric forms and 89 crystallographic structures, synthesis of Fe-based carbon 38 This article is protected by copyright. All rights reserved 1 ARTICLE 1 nanocomposite with controllable morphologies remains a28 storage system. Recently, we have been interested in rational 2 challenge. 29 utilizations of Fe-based nanocomposite electrode materials. 3 The application area of polymer, such as co-polymer, flame30- In this study, Fe-based nanoparticles were uniformly 4 retardant foam, recycled plastic, ethyl oleate esterification, is31 anchored onto hybrid carbon structure of Na-C70 and N-GN and 5 wide and could match with different compound and simple32 formed the Na-C70/N-GN/FBNCs with various morphologies via a 6 substance, for example, react with inorganic substance for33 simple in situ synthesis method. We explored the possibility of 7 TiO2/SnO2 nanofibers, with negative permittivity flexible34 using multifunction sodium lignosulfonate (SLS) as the structural 8 membranous metacomposites, and energy materials, such as35 template and the main raw material to fabricate Na-C70/N- 9 battery or supercapacitor electrode materials, except these,36 GN/FBNCs anodes for SIBs and LIBs. The results show that the 10 polymer usually as surfactant to participant synthesis37 skeleton of SLS and a large amount of sulfonic group in SLS 11 composites. [25-31] In this article, we use polymer sodium38 enable its use as carbon and sulfur sources that can control the 12 lignosulfonate and inorganic ferric nitrate to synthesis composite39 formation of Fe-based nanoparticles and Na-C70/N-GN by 13 and as sodium ion battery anode. Commercial sodium40 means of ion exchange and crosslinking reaction. The various 14 lignosulfonate (SLS) is a cheap anionic polymeric surfactant41 polar functional groups in SLS, such as hydroxyl and carboxyl 15 derived from by-products of the cooking process in sulfite42 groups, might easy chelate iron ions and control self-assembly [32] 16 pulping in the manufacture of paper. Molecular mass of SLS43 of particles, thus achieving the in situ synthesis of Na-C70/N- 17 ranges from several hundred to several million according to the44 GN/FBNCs nanocomposite. The particles with different 18 preparation conditions. The degree of sulfonation of SLS45 morphologies in the nanocomposite might be able to affect the 19 molecules is 0.4-0.5 per phenylpropane unit (Fig. 1c) and its46 Na-ion storage and transport synergistically, and importantly, 20 carbon content is greater than 60% with a quite high ash47 this kind of synergistic effect, if exists, cannot be easily attained [33] 21 content. Since SLS owns a three dimensional cross-linked48 with some other synthesis methods. As expected, the Na-C70/N- 22 structure containing C6–C3 hydrophobic basic structure with a49 GN/FBNCs anodes exhibited larger specific capacity, higher rate 23 variety of reactive groups in its molecules, such as hydrophilic50 performance, ultra-high coulombic efficiency as well as 24 hydroxyl, carboxyl, and sulfonic acid groups, an aqueous51 outstanding cycling stability compared to the pristine FeS2 and [34] 25 solution of SLS shows amphiphilic properties.