Upcycling of Electroplating Sludge into Ultrafine Sn ... - ACS Publications

Jan 24, 2019 - School of Environment and Energy, The Key Laboratory of Pollution Control ... China University of Technology , Guangzhou , Guangdong 51...
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Upcycling of electroplating sludge into ultrafine Sn@C nanorods with highly stable lithium storage performance Xucun Ye, Zhihua Lin, Shujie Liang, Xihe Huang, Xiaoyuan Qiu, Yongcai Qiu, Xueming Liu, Dong Xie, Xunhui Xiong, and Hong Deng Nano Lett., Just Accepted Manuscript • Publication Date (Web): 24 Jan 2019 Downloaded from http://pubs.acs.org on January 24, 2019

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Upcycling of electroplating sludge into ultrafine Sn@C nanorods with highly stable lithium storage performance Xucun Ye a, Zhihua Lin a, Shujie Liang a, Xihe Huang a, Xiaoyuan Qiu a, Yongcai Qiu a, Xueming Liu a, Dong Xieb, Xunhui Xionga*, and Hong Deng a,c* a

School of Environment and Energy, The Key Laboratory of Pollution Control and

Ecosystem Restoration in Industry Clusters (Ministry of Education), South China University of Technology, Guangzhou, Guangdong 510006, China b

Guangdong Engineering and Technology Research Center for Advanced Nanomaterials,

School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, China c

Guangdong Engineering and Technology Research Center for Environmental Nanomaterials,

South China University of Technology, Guangzhou, Guangdong 510006, China Corresponding Author *Email: [email protected]; [email protected]

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Abstract Sn-based anode materials have become potential substitutes for commercial graphite anode due to their high specific capacity and good safety. In this paper, ultrafine Sn nanoparticles embedded in nitrogen and phosphorus co-doped porous carbon nanorods (Sn@C) are obtained by carbonizing bacteria that adsorb the Sn electroplating sludge extracting solution. The as-prepared Sn@C rod-shaped composite exhibits superior electrochemical Li-storage performances, such as a reversible capacity of approximate 560 mAh/g at 1 A/g and an ultralong cycle life exceeding 1500 cycles, with approximately no capacity decay. The ultrastable structure of the Sn@C was revealed using in situ transmission electron microscope (TEM) at the nanoscale and indicated that the Sn@C composite could restrict the volume expansion of Sn nanoparticles during the lithiation/delithiation cycles. This work provides a new insight into addressing the electroplating sludge and designing novel LIBs anodes. Keyword: Sn-nanoparticle, Electroplating Sludge, lithium-ion batteries, anode, high stability

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With the widespread use and rapid development of portable electronic devices and electric vehicles, it has become more and more urgent to develop lithium ion batteries (LIBs) with high energy density, high power density and long cycle life.1 Sn-based LIBs anode materials have become potential substitutes for commercial graphite anodes due to their high theoretical capacity (992 mA h/g for Li4.4Sn), high safety, and have received extensive attentions.2 However, Sn-based materials are usually accompanied by large volume changes during charge and discharge, and particle aggregation is prone to occur, thereby limiting their further development and application in LIBs.3–5 Thus, to overcome the aforementioned problems, two strategies are generally adopted: (a) Reduce the size of Sn particles to inhibit the mechanical stress when the volume of tin expands.6,7 (b) Construct porous micro/nanostructures composites with other materials, such as carbon, to accommodate the volume expansion and prevent the coarsening of Sn.8–11 Furthermore, global tin reserves have declined from 6.1 million tons to 4.7 million tons from 2005 to 2016, and approximately 266,000 tons of tin is mined annually.12 If there is no efficient method to recycle and reuse the Sn, it is anticipated that the Sn supply will run out in 20 years at the current consumption rate. As a typical electroplating sludge, the concentration of SnO2 is 150 g/L in the tinplate electroplating sludge from the manufacture of printed broads and the electroplating sludge from the production of fluoroborate electrolyte contains approximately 50% Sn.13,14 However, most of this waste is disposed to landfills and is not well managed. In fact, the Sn recycled from the sludge would be the source for synthesising the Sn-based anode which could achieve high value utilization of electroplating waste to balance the contradiction between the Sn storage and energy requirement. Besides, biosystems have long been regarded as attractive templates for constructing and organizing nanostructures with interesting features.15,16 Bacterial proteins and lipids, mainly composed of peptidoglycans, with the functional groups, including the carboxyl group, the phosphoryl 3 ACS Paragon Plus Environment

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group, the hydroxyl group, the amino group and the amide group, can bind with metal ions by coordination bonds.17,18 Thus, bacteria are excellent templates for nanostructured metal/carbon composites to designing high-performances Sn-based anodes for LIBs via a bacterial-template method. The advantages of this method can be concluded as follows. First, bacteria could survive even under extreme conditions, such as high concentrations of heavy metals due to its strong adaptability.15,16 Besides, Sn nanoparticles (NPs) are well distributed and anchored in a porous carbon skeleton by interacted with bacteria, which significantly improves the electrochemical cycling performance.8,19 Finally, the organic macromolecules, such as teichoic acids, peptide polysaccharides and proteins, in bacteria produced a nitrogen and phosphorus co-doped carbon matrix, which not only boosts the electronic conductivity but also provides a stronger chemical affinity to active materials.20–25 Here we reported that the bacteria can be exploited to recover the Sn from the electroplating sludge, which then can be converted into ultrafine Sn nanoparticle embedded in nitrogen and phosphorus co-doped porous carbon nanorods (Sn@C), which shows excellent lithium storage performances. In situ TEM was performed to investigated the structural stability of Sn@C during the lithiation/delithiation cycles. It was observed that the robust carbon matrix could buffer the mechanical pressure generating by the expansion of Sn NPs during the lithiation/delithiation process, which confirms that both the ultrafine Sn NPs and carbon matrix derived from bacteria take great contribution to the long cycling stability and excellent rate performance. Figure 1 schematically illustrates the synthesis process of the as-prepared sample. First, the Sn leachate was acquired by acid leaching from the Sn-contained electroplating sludge, which contains Sn (62.31% wt %) according to the inductively coupled plasma mass spectrometry (ICP-MS) analysis (Tables S1). Then, the nitrogen and phosphorus co-doped porous carbon nanorods with embedded ultrafine Sn NPs (Sn@C) was constructed by adding Bacillus subtilis into the Sn leachates, followed by a calcination process in Ar. According to 4 ACS Paragon Plus Environment

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the results of ICP-MS, the Sn content of Sn@C composites 35.09 wt % (Tables S2). Powder X-ray powder diffraction (XRD) was used to characterize the chemical composition and crystal structure. There are no obvious diffraction peaks of Sn compound in the XRD pattern of the Bacillus subtilis (Figure S1) after interaction with Sn (Sn@BS), which indicates that the Sn element is an amorphous compound in bacteria after the interaction between the bacteria and the metal ions. After calcination, the XRD pattern of the as-prepared sample (Figure 2a) shows eight characteristic peaks at 30.6°, 32.0°, 43.9°, 44.9°, 55.3°, 62.5°, 63.8° and 64.6°, respectively, which correspond to the standard peaks of Sn (JCPDS No. 04-0673). The small peaks at 31.73°, 32.32° and 33.01° can be identified as Sn3O4 (JCPDS No. 160737), which was usually attributed to the incomplete reduction during the annealing process in the inert atmosphere. The weight percentage of Sn3O4 in the Sn@C composite is calculated to be 3.34 wt.% from the Rietveld refinement results of XRD pattern. The Raman analysis (Figure 2b) further identifies the composition of the as-prepared sample. The Sn@C and pristine carbon derived from pure bacteria exhibited distinctive D and G peaks at 1308 and 1596 cm-1, respectively. The ratio of the D-band to the G-band shows the disordered property of the composite, which is beneficial to LIBs anode because the disordered structure has been proven to improve the capacity of carbon materials.26–28 By calculation, the ID/IG of pristine carbon and the Sn@C are 0.88 and 0.93, respectively, demonstrating that the structure of Sn@C is more disordered than pristine carbon after interaction with the metal. X-ray photoelectron spectroscopy (XPS) measurement was also used to characterize the chemical composition in the Sn@C. According to the survey spectra, Sn, C, O, N, and P, are detected as the main elements of the Sn@C (Figure 2c). The deconvolution result of Sn 3d spectrum is shown in Figure 2d. The Sn 3d5/2 peak is split into three peaks with binding energies of 487.5 eV (Sn4+), 486.8 (Sn2+) and 485.3 (Sn0), while the Sn 3d3/2 signal is deconvoluted into another three peaks at binding energies of 495.9 eV (Sn4+), 495.2 eV (Sn2+) 5 ACS Paragon Plus Environment

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and 493.9 eV (Sn0). The weak signal of Sn0 in the Sn 3d spectrum indicates that the Sn NPs are covered by SnOx, which is consistent with the XRD refinement results. SnOx species are also found in the O 1s spectrum at 532.1 eV (Figure S2a)7. It is worth to note that the O 1s spectrum of Sn@C shifts to 531.6 eV (Figure S2b) when compared to the pristine carbon, further proving the existence of SnOx in the Sn@C29. The presented SnOx can improve the total capacity of the composite as the reduction of SnOx to Sn corresponds to a higher capacity. To investigate the bonding state of nitrogen and phosphorus, the high-resolution N 1s peak and the P 2p peak were analysed (Figure S2c, d). The fitting result of the N 1s peak shows graphitic N (400.8 eV), pyridinic N (398.2 eV) and pyrrolic N (399.7 eV). The phosphorus includes metaphosphates (134.2 eV) and phosphates & pyrophosphates (133.4 eV). Fourier transform infrared spectroscopy (FT-IR) analysis was performed to verify the presence of functional groups from Bacillus subtilis in the sorption process, which could explain the interaction between functional groups and metal ions in the bacteria (Figure S3). Compared with pure bacteria, the existence of bimodal peaks at 500-800 cm-1 for the Sn@BS can be assigned to the vibration of Sn-OH and Sn-O-Sn,18 indicating that the Bacillus subtilis successfully bound with the Sn through numerous active sites. After the heat treatment, the peaks are appeared in the both Sn@C and Sn@BS at lower wavenumbers of about 600 cm–1, which are the typical peaks of the Sn-O-Sn antisymmetric and symmetric vibrations. The disappeared peaks of the protein suggest that the Bacillus subtilis were converted to carbon. Additionally, a porous carbon material derived from bacteria can be obtained due to the decomposition of organic macromolecules. The nitrogen adsorption-desorption isotherms of the Sn@BS and Sn@C were investigated (Figure S4a,b). According to the International Union of Pure and Applied Chemistry (IUPAC) classification, the observed hysteresis loop is ascribed to type H4 loops, indicating the presence of microspores in the composite (Figure S4b). The diameter of the microspores is calculated to be approximate 1.25 nm from the adsorption branch using the density functional theory (DFT) model (inset in Figure S4b). 6 ACS Paragon Plus Environment

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Based on the nitrogen quantity adsorbed at different relative pressures, the specific surface area of the Sn@C is calculated to be 179.07 m2/g, which is much higher than that of the Sn@BS (5.28 m2/g). The higher surface area is believed to enhance the electrochemical performance of the composite, because the porous structure is beneficial to the diffusion of lithium ions through the carbon matrix and the infiltration of electrolytes during charge/discharge.30 The sizes and morphologies of the bacteria and the as-synthesized Sn@BS and Sn@C were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), high-resolution TEM (HRTEM), and the results are presented. Figure 3 and Figure S5 show the typical SEM images of the rod-like structured bacteria and the Sn@BS, in which the bacteria retain their original rod-structure with a length of approximate 1 μm and an average diameter of approximately 400-500 nm. Meanwhile, the annealing process does not damage the bacterial morphology and microstructure, maintaining the rod-shaped structure. Further understand the internal information of the Sn@C, a slicing study was performed. TEM analyses were performed on the cross-section of the as-prepared sample, which reveals that the Sn particles are homogeneously distributed throughout the composite material without distinct agglomeration (Figure 3c). It is well-known that biosorption is the absorption of metal ions by organisms, which under normal circumstances, includes the following steps: First, the metal ions are adsorbed on the cell surface by the extracellular polymer or the functional groups on the cell wall, which binds to the heavy metal ions, a type of passive adsorption; second, the metal ions are actively adsorbed by living cells, which make full use of certain enzymes on the cell surface, thereby adsorbing metal ions on the cell surface, and heavy metal ions on the cell surface are further transferred into the cells under the action of transmission and accumulation. This process could explain how Sn can be evenly distributed in bacteria. The HRTEM image (Figure 3d) further verifies the singlecrystalline nature of the Sn NPs with a diameter of 10 nm. Moreover, highly regular fringes 7 ACS Paragon Plus Environment

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are observed with an interlayer distance of approximately 0.279 nm, which agrees well with the separation between the (101) lattice planes.31 Further explore the distribution of Sn, the elemental distribution was examined using energy dispersive X-Ray spectroscopy (EDX) elemental mappings. As shown in Figure 3e-i, the Sn, N, and P atoms are uniformly distributed throughout the Sn@C, which confirms that the bacteria can be an excellent matrix to prevent agglomeration during the high temperature heating process since the Sn has a low melting point 231.9 °C. The carbon matrix, which is obtained by bacteria carbonization, not only acts as a buffer layer to limit Sn volume expansion but also prevents the agglomeration of Sn particles, thereby designing a carbon-encapsulated Sn structure can significantly improve the structural stability and capacity retention. Recent investigations have indicated that heteroatom doping can significantly enhance the electrochemical performance of the carbon materials.32–35 As compared to other artificial atom doping materials, porous carbon materials obtained by high-temperature bacteria carbonization has more uniform distributions of nitrogen and phosphorus, therefore it is expected to exhibit a better electrochemical performance. The electrochemical performances of the Sn@C as a LIBs anode were evaluated by assembling CR2025 coin-type cells. Cyclic voltammetry (CV) was applied to investigate the electrochemical activity of the Sn@C. Figure 4a shows the CV of the initial three cycles at a scan rate of 0.1 mV/s from 0.01 to 3 V. From the first cathodic sweep, the four reduction peaks at 0.28, 0.93, 1.11, 1.55 V are attributed to the lithium insertion into Sn. A broad reduction peak that is cantered at 0.8 V is observed in the first lithiation cycle but disappeared in the following cycles, which is usually attributed to the decomposition of the electrolyte and formation of a solid-electrolyte interphase (SEI) film, indicating an irreversible capacity loss during the first charge-discharge process.36 However, after the first cycle, only one small peak at 0.35 V is observed, which is assigned to the formation of a LixSn alloy (Sn + 4.4Li+ + 4.4e→Li4.4Sn).37,38 The irreversible peaks, corresponding to the catalytic decomposition of the Sn 8 ACS Paragon Plus Environment

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metal, at 1.05 and 1.55 V, were not observed from the second cycle onward, indicating that the Sn particles are well encapsulated in the carbon matrix. In the anodic sweep, the oxidation peaks at 0.51 and 0.63 V, correspond to the delithiation reaction of the LixSn alloy. The profile of the third scan overlaps well with the second scan, suggesting the excellent electrochemical reversibility of the Sn@C anodes. As shown in Figure 4b, the rate performance of the Sn@C was investigated at increasing current densities. The corresponding charge-discharge profiles are given in Figure 4c. The first discharge and charge capacities of the Sn@C are 915.9 and 644.2 mAh/g, respectively, indicating a Coulombic efficiency (CE) of 70.3 %. Compared to the pristine carbon derived from Bacillus subtilis, the first discharge and charge capacities are 771.2 mAh/g and 380.8 mAh/g, corresponding to a CE of 49.38 % (Figure S6). During the initial cycle, the large capacity loss is mainly assigned to the irreversible reactions, such as electrolyte decomposition and the unescapable formation of a SEI film. The Sn@C exhibits an excellent rate performance and presents high reversible capacities of 660, 640, 600, 535, 460, 380 and 297 mAh/g at the current densities of 0.1, 0.2, 0.5, 1, 2, 5, 10 A/g, respectively. Additionally, while the current density was adjusted to 0.1 A/g, the specific capacity is almost completely recovered, indicating that the rod-like structure carbon matrix could maintain the integrity of the electrode and accommodate the change of the current density during the charge and discharge process. The detailed reaction kinetics of Sn@C in LIBs also investigated using electrochemical impedance spectroscopy (EIS) in the frequency range 10 MHz to 0.01 Hz at a 10 mV amplitude. Figure 4d displays the typical Nyquist plot of the Sn@C anodes after the 1st, 200th, 500th, and 1000th cycle. The smaller diameter of the semicircle of the 200th, 500th and 1000th cycles indicates that the charge–transfer resistances become smaller during charge/discharge. The low-frequency sloping line of the first cycle is longer than the line of the 200th, 500th and 1000th cycles, confirming that the transportation of Li+ in the Sn@C during the first cycle is 9 ACS Paragon Plus Environment

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slower than that after hundreds of cycles. The decrease of the impedance is conducive to enhancing the specific capacity and cycling performance of the LIBs, confirming the excellent electrochemical performance of the Sn@C anodes. This phenomenon can be ascribed to the unique architecture of the ultrafine Sn NPs embedded in the porous rod-like carbon structure, which facilitates the fast Li+ ion diffusion and superior contact between the active material and electrolyte. Promoting the industrial application of high energy density LIBs, a long-term cyclic stability is needed (Figure 4e). Further demonstrate the excellent cycling stability of the Sn@C, the cell was cycled up to 1500 cycles under a current density of 1 A/g. The specific capacity of the Sn@C has a slight increase, stabilizes at 560.5 mAh/g after the 500 cycles, and reaches its highest value of 611.6 mAh/g at the 1010th cycle. Meanwhile, the galvanostatic cycling of Sn@C composite in the potential range of 0.01~1 V was also carried out (Figure S7a). The reversible capacities keep a slow increase (from 335.2 to 385.2 mAh/g) during the first 200 cycles, and the variation of capacity in this region during cycling is quite similar to the capacity of Sn@C composite at 0.01~3 V (Figure 4e). Considering that pristine carbon anode delivers a stable capacity (Figure S8), the capacity increase of Sn@C composite occurrs mainly in the potential range of 0.01∼1 V, indicating the alloy reaction of Sn and Li is highly reversible. Furthermore, the coulombic efficiency of the Sn@C is also remarkable; after first two cycles, it can still retain more than 99.85 % after 1500 cycles, indicating the effective transportation of electrons and diffusion of Li+ on the electrode. The cycling stability of pristine carbon was also investigated at the current density of 1 A/g. The capacity of pristine carbon, derived from Bacillus subtilis, stabilized at approximate 378.8 mAh/g (Figure S8). It can cycle more than 400 cycles without capacity loss, indicating a good cycling stability of pristine carbon derived from Bacillus subtilis. As compared to other Sn-based materials (Table S3), the Sn@C exhibits a remarkable cycling stability, capacity retention, and superior rate capacity. 10 ACS Paragon Plus Environment

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In situ TEM was used to investigated the real-time structure stability of Sn@C during the lithiation/delithiation processes. The setup for the in situ TEM device is illustrated in Figure 5a, where a randomly selected Sn@C that was connected to the Au tip serves as a working electrode and the Li on the W nanowire tip works as a counter electrode. As shown in Figure 5b,c, the size expansion of the Sn NPs is clearly observed and the diameter of Sn NPs is enlarged from a few nanometer to about 15 nm and there are no cracks or fractures occurred in the Sn@C composites during the alloying process (Movie S1). As shown in Figure 5d-f, Sn NPs undergo two “expansion/contraction” processes in response to lithiation/delithiation cycles (Movie S2). The size expansion/contraction of the inner Sn NPs presents periodic changes during the lithation/delithiation cycles. Despite that the Sn NPs are expanded dramatically, the carbon matrix can buffer the stress of NPs and maintain the original rob-like shape of Sn@C without apparent deformation. As proven by the in situ TEM study, the rodlike structure of the Sn@C can effectively accommodate the mechanical strain and stress of the volume change and prevent the pulverization of the Sn NPs during the charge/discharge process, which explains the excellent cyclic stability and rate capability of the Sn@C anodes. The evidence of the structural stability of the Sn@C anodes was also revealed using SEM (Figure S9). It is observed that most of the cycled Sn@C composite retains the original rodlike structure after 300 charge/discharge cycles at a current density of 1 A/g. The cycled Sn@C shows little difference from the original Sn@C on the surface, which can be attributed to the SEI layer. In conclusion, this experiment used environmental hazardous waste and prepared Sn@C composite materials to solve the cycling problem of Sn-based anode for LIBs. Moreover, the real-time structural stability of Sn@C was proven by in situ TEM during the charge/discharge process. As a LIB anode, the Sn@C exhibits a long cycle life (~560 mAh/g irreversible capacity under the current density of 1 A/g after 1500 cycle) and a high rate capability (380 mAh/g at 5 A/g). These excellent performances are mainly based on three unique properties: 11 ACS Paragon Plus Environment

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(1) The nanometer size of Sn particles (~10 nm); (2) the homogeneous distribution of Sn in the carbon matrix; and (3) the nitrogen and phosphorus co-doped carbon matrix. The features mentioned above could dramatically decrease the mechanical stress and prevent the aggregation of Sn nanoparticles during charge/discharge, which would greatly improve the electrochemical performance of the Sn@C. We believed that this novel strategy could be extended to other transition metal/metal oxide anode for next generation LIBs.

Supporting Information Supporting Information is available free of charge on the ACS Publication website http://pubs.acs.org. Details of experimental methods, characterizations, electrochemistry; Additional figures (Figure S1-9), table (Table S1-3) and movie (Movie S1-2). Conflicts of interest There are no conflicts to declare. Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No. 21777046 and 51874142), the Guangdong Innovative and Entrepreneurial Research Team Program (No. 2016ZT06N569), Guangzhou Science and Technology Project (No. 201803030002).

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References (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28)

Armand, M.; Tarascon, J. M.. Nature 2008, 451 (7179), 652–657. Idota, Y.; Kubota, T.; Matsufuji, A.; Maekawa, Y.; Miyasaka, T. Science. 1997, 276 (5317), 1395–1397. Huang, J. Y.; Zhong, L.; Wang, C. M.; Sullivan, J. P.; Xu, W.; Zhang, L. Q.; Mao, S. X.; Hudak, N. S.; Liu, X. H.; Science. 2010, 330 (6010), 1515–1520. Ebner, M.; Marone, F.; Stampanoni, M.; Wood, V. Science. 2013, 342 (6159), 716–720. Ji, L.; Tan, Z.; Kuykendall, T.; An, E. J.; Fu, Y.; Battaglia, V.; Zhang, Y. Energy Environ. Sci. 2011, 4 (9), 3611–3616. Ardhi, R. E. A.; Liu, G.; Tran, M. X.; Hudaya, C.; Kim, J. Y.; Yu, H.; Lee, J. K. ACS Nano 2018, 12 (6), 5588–5604. Zhu, Z.; Wang, S.; Du, J.; Jin, Q.; Zhang, T.; Cheng, F.; Chen, J. Nano Lett. 2014, 14 (1), 153–157. Wu, C.; Maier, J.; Yu, Y. Adv. Funct. Mater. 2015, 25 (23), 3488–3496. Mao, M.; Yan, F.; Cui, C.; Ma, J.; Zhang, M.; Wang, T.; Wang, C. Nano Lett. 2017, 17 (6), 3830–3836. Kang, S.; Chen, X.; Niu, J. Nano Lett. 2018, 18 (1), 467–474. Shi, H.; Fang, Z.; Zhang, X.; Li, F.; Tang, Y.; Zhou, Y.; Wu, P.; Yu, G. Nano Lett. 2018, 18, 3193–3198. USGS, Mineral Commodity Summaries-Tin, 2007−2017. https://minerals.usgs.gov/minerals/pubs/commodity/tin/ Stefanowicz, T.; Golik, T.; Napieralska-Zagozda, S.; Osińska, M. Conserv. Recycl. 1991, 6 (1), 61–69. Kerr, C. Trans. IMF 2004, 82 (1–2), B7–B12. Rosant, C.; Avalle, B.; Larcher, D.; Dupont, L.; Friboulet, A.; Tarascon, J. M. Energy Environ. Sci. 2012, 5 (12), 9936–9943. Sun, H.; Cao, L.; Lu, L. Energy Environ. Sci. 2012, 5 (3), 6206. Weidenmaier, C.; Peschel, A. Nat. Rev. Microbiol. 2008, 6 (4), 276–287. Lim, A.-H.; Shim, H.-W.; Seo, S.-D.; Lee, G.-H.; Park, K.-S.; Kim, D.-W. Nanoscale 2012, 4 (15), 4694. Zu, L.; Su, Q.; Zhu, F.; Chen, B.; Lu, H.; Peng, C.; He, T.; Du, G.; He, P.; Chen, K.; et al. Adv. Mater. 2017, 29 (34), 1–9. Xia, Q.; Yang, H.; Wang, M.; Yang, M.; Guo, Q.; Wan, L.; Xia, H.; Yu, Y. Adv. Energy Mater. 2017, 7 (22). Ye, G.; Zhu, X.; Chen, S.; Li, D.; Yin, Y.; Lu, Y.; Komarneni, S.; Yang, D. J. Mater. Chem. A 2017, 5 (18), 8247–8254. Liu, W.-J.; Tian, K.; Ling, L.; Yu, H.-Q.; Jiang, H. Environ. Sci. Technol. 2016, 50 (22), 12421–12428. Ai, W.; Wang, X.; Zou, C.; Du, Z.; Fan, Z.; Zhang, H.; Chen, P.; Yu, T.; Huang, W. Small 2017, 13 (8), 1–9. Zhang, Y.; Rui, X.; Tang, Y.; Liu, Y.; Wei, J.; Chen, S.; Leow, W. R.; Li, W.; Liu, Y.; Deng, J.; et al. Adv. Energy Mater. 2016, 6 (10), 1–9. Dong, J.; Xue, Y.; Zhang, C.; Weng, Q.; Dai, P.; Yang, Y.; Zhou, M.; Li, C.; Cui, Q.; Kang, X.; et al. Adv. Mater. 2017, 29 (6), 1–8. Etacheri, V.; Hong, C. N.; Pol, V. G. Environ. Sci. Technol. 2015, 49 (18), 11191– 11198. Zhang, X.; Zhu, G.; Wang, M.; Li, J.; Lu, T.; Pan, L. Carbon. 2017, 116, 686–694. Zheng, T. J. Electrochem. Soc. 1995, 142 (11), L211. 13 ACS Paragon Plus Environment

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Li, Y.; Lv, X.; Lu, J.; Li, J. J. Phys. Chem. C, 2010, 21770–21774. Trogadas, P.; Ramani, V.; Strasser, P.; Fuller, T. F.; Coppens, M. O. Angew. Chemie Int. Ed. 2016, 55 (1), 122–148. Liu, J.; Kopold, P.; Wu, C.; Van Aken, P. A.; Maier, J.; Yu, Y. Energy Environ. Sci. 2015, 8 (12), 3531–3538. Lv, Q.; Wang, S.; Sun, H.; Luo, J.; Xiao, J.; Xiao, J. W.; Xiao, F.; Wang, S. Nano Lett. 2016, 16 (1), 40–47. Zhang, C.; Wang, X.; Liang, Q.; Liu, X.; Weng, Q.; Liu, J.; Yang, Y.; Dai, Z.; Ding, K.; Bando, Y.; et al. Nano Lett. 2016, 16 (3), 2054–2060. Shin, W. H.; Jeong, H. M.; Kim, B. G.; Kang, J. K.; Choi, J. W. Nano Lett. 2012, 12 (5), 2283–2288. Sun, F.; Liu, X.; Wu, H. Bin; Wang, L.; Gao, J.; Li, H.; Lu, Y. Nano Lett. 2018, 18, 3368–3376. Aravindan, V.; Lee, Y.; Madhavi, S. Adv. Energy Mater. 2017, 1602607, 1–17. Zhang, H.; Shi, T.; Wetzel, D. J.; Nuzzo, R. G.; Braun, P. V. Adv. Mater. 2016, 28 (4), 742–747. Shi, X.; Song, H.; Li, A.; Chen, X.; Zhou, J.; Ma, Z. J. Mater. Chem. A 2017, 5 (12), 5873–5879.

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Figure 1. Schematic illustration of the synthesis process of the Sn@C.

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Figure 2. (a) Rietveld refinement XRD pattern of Sn@C. (b) Raman spectra of the Sn@C and pristine carbon. (c) The full XPS spectrum of the Sn@C. (d) High resolution Sn 3d XPS spectrum of the Sn@C.

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Figure 3. (a) SEM images of the Sn@BS. (b) SEM image of the Sn@C. (c) Cross-section TEM images of the Sn@C. (d) Cross-section HRTEM images of the Sn@C. (e) The STEMEDX elemental mapping of the Sn@C. (f-i) C, N, P and Sn distributions of the Sn@C, respectively.

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Figure 4. Electrochemical performances of the Sn@C as an anode of a LIBs: (a) Cyclic voltammetry at a scanning rate of 0.1 mV/s. (b) specific discharge capacity evolution at various charge/discharge rates from 0.1 to 10 A/g. (c) Charge/discharge voltage profiles of the Sn@C from 0.1 to 10 A/g. (d) Comparison of electrochemical impedance spectroscopy (EIS) curves of the Sn@C before and after the 200th, 500th, 1000th cycles. (e) Long cycling performance of the Sn@C as an anode of a LIBs at 1 A/g.

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Figure 5. (a) Schematic of dry cells based on the Sn@C for the in situ TEM study. (b-f) Time-lapse TEM images for the Sn@C during a full lithiation–delithiation process with an applied voltage of ±3 V between the W and Au electrodes.

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