Graphitic, Porous, and Multiheteroatom Codoped Carbon Microtubes

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Letter

Graphitic, Porous and Multi-heteroatoms Co-doped Carbon Microtubes Made from Hair Wastes: A Superb and Sustained Anode Substitute for Li-ion Batteries Jianhui Zhu, Siyuan Liu, Yani Liu, Ting Meng, Lai Ma, Han Zhang, Minquan Kuang, and Jian Jiang ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b04114 • Publication Date (Web): 19 Oct 2018 Downloaded from http://pubs.acs.org on October 21, 2018

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Graphitic, Porous and Multi-heteroatoms Co-doped Carbon Microtubes Made from Hair Wastes: A Superb and Sustained Anode Substitute for Liion Batteries Jianhui Zhu,a* Siyuan Liu,b,c Yani Liu,b,c Ting Meng,b,c Lai Ma,b,c Han Zhang,b,c Minquan Kuang,a Jian Jiangb,c* a

School of Physical Science and Technology, Southwest University, No. 2 Tiansheng Road, Beibei District, Chongqing

400715, P.R. China. b

Institute for Clean Energy & Advanced Materials, Faculty of Materials and Energy, Southwest University, No. 2

Tiansheng Road, Beibei District, Chongqing 400715, P.R. China. c

Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies, No. 2 Tiansheng Road,

Beibei District, Chongqing 400715, P.R. China. To whom correspondence should be addressed: Tel: +86-23-68254842. *

E-mail: [email protected] (J. Zhu); [email protected] (J. Jiang).

Abstract: Turing household wastes into useful battery anodes is always a rational way to retard the graphite resources exhaustion and prevent the living environment deterioration. Though great efforts have been devoted, nearly all evolved carbons are intrinsically amorphous and dense, which is adverse to ions diffusions, electrons transfer and actives utilization for battery usage. Herein, by selecting common hair wastes as the example materials, we propose a smart catalytic engineering protocol to make graphitic, porous and multi-heteroatoms co-doped carbon microtube anodes for sustained Li-ion batteries. The Ni-based nanofilm matrix evenly immobilized on all hair surface plays a key role on the rapid hairs graphitization and deep pores formation. Such evolved carbons with unique functionalized properties can well make up for the shortcomings of hair-carbonized products, exhibiting far superior anodic behaviors on reversible capacity/actives utilization efficiency, cyclic stability/endurance (no capacity fading in 1000 cycles) and rate capabilities. The full cell testing furthermore justifies their great potential usage in Li-ion batteries. This paradigm work may bring new opportunities to recycle and evolve the vast biomass wastes into advanced anode substitutes for energy-storage applications. Keywords: Hair wastes; Graphitic and porous carbon microtube; Multi-heteroatoms doped; Sustained anode substitute; Li-ion Batteries

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Introduction The rapid depletion of fossil resources is conceived as a major crisis that would mostly impact our daily life in near future. Typically, underneath the current giant consumption rate, the graphite mineral deposits for Li-ion batteries (LIBs) usage would be exhausted in next 20 years.1 Therefore, extensive researches have been directed to seeking for applicable substitutes for natural graphite, which are required to be highly renewable, environmental benign, abundant/low-cost and perfectly with higher energy/power densities.2-4 In addition to energy crisis, the living environmental deterioration caused by solid wastes accumulation also becomes a tough, serious and worldwide issue. In an attempt to tackle above problems, the recycle and utilization of readily available household wastes as raw materials to produce electrode materials for LIBs is regarded to be a smart and efficient strategy that can kill two birds with one stone.5 The human hair, one of common wastes easily collected from barbershops and hair salons, has already been conceived as a promising and rational choice to make sustainable carbon anodes since they are rich in functionalized heteroatoms that can contribute additional Li-storage capacity via reversible redox reactions.6-8 Nevertheless, current mainstream treatments toward wastes are still the straightforward calcination and then a series of post-processing (e.g., alkaline corrosion, surface modification, incorporation of extra nanoactives, etc.), resulting in the generation of highly porous or hierarchically hybrid electrode architectures.9-12 Though using this engineering concept indeed pushes forward the development of sustained LIBs anodes, several formidable challenges/issues are still in the way for further industrialization. Primarily, unless the case that the heating temperature exceeds 1100 K, the hairscalcined carbon products are rather dense, bulky and intrinsically amorphous/less graphited (turbostratic graphite nanodomains are randomly distributed).13 Thus, either Li+ diffusion/intercalation

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or electrons transfer is thermodynamically impeded by disorderly arranged carbon atoms, giving rise to poor actives utilization efficiency in battery operations and large irreversible “dead” capacities due to undesired traps of partial Li+ into defects. Despite making hierarchical porous structures on such carbon species via KOH activation method may be an effective way to settle aforementioned issue, the derived samples with high specific surface areas are more close to activated carbons, tending to exhibit supercapacitor-like behaviors in the total working voltage range (rather than intercalation/deintercalation cases at specific potentials).14 Also, this activation process would inevitably deteriorate the anodic electrical conductivity, not beneficial to the rate performance of LIBs. Proper treatments toward the vast of solid wastes via facile/economical methods as well as the delicate control of intrinsic properties for evolved carbons, therefore, are highly required in a long-term development perspective. Aimed to make reliable/applicable anodic candidates, we herein select hair wastes as the study paradigm and put forward a simple interfacial engineering protocol to convert hairs into graphitic and porous carbon microtubes (GP-CMTs) with multi-heteroatoms (N, S, O) co-doped properties. Particularly noteworthy is that the nickel nitrate hydroxide (NNH) nanofilms evenly and tightly grown on all hair external surface play a key catalytic role in enabling the rapid biomass graphitization at a moderate temperature (650 oC) and helping to dig deep pores on each GP-CMT, forming rich and convenient channels for Li+ diffusions. Thanks to synergistic cooperations between highly active heteroatoms and unique intrinsic structural features, such GP-CMTs can well make up for the shortcomings of directly carbonized counterparts, capable of showing superior anodic behaviors on reversible capacity (Max.: ~689 mAh/g), actives utilization efficiency, long-term cyclic stability/endurance (no capacity fading in 1000 cycles) and excellent rate capabilities (still retaining a Max. capacity of ~387 mAh/g even at 6 A/g). Furthermore, the full cell testing justifies their great

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potential usage in Li-ion batteries. This work may open up a smart engineering way for the recycle of biomass wastes and demonstrate a superb and sustainable substitute to traditional graphite for LIBs applications.

Experimental Section Synthesis of GP-CMTs: The initiating human hairs are obtained from a Chinese male volunteer. The hair wastes were initially cut into small pieces with an average length of ~0.5 cm, washed with distilled water and ethanol for several times, and dried in an electric oven at 80 oC. Later, ~0.6 g clean hair samples, ~0.5 g hexamethylenetetramine (C6H12N4; denoted as HMT) and 0.25 g Ni(NO3)2·6H2O were dissolved in 50 mL deionized water under constant magnetic stirring for 30 min. The obtained mixture was then transferred into a 100 ml glass container and kept sealed at 95 oC for 6 h. Afterwards, the resultant NNH@hairs products were collected, washed with distilled water several times and dried at 80 oC in electrical oven. Afterwards, the fiber samples were loaded onto a quartz boat, put into the center of a quartz tube and subjected to a thermal treatment conducted at 650 oC under the Ar flow (Heating rate: 10 oC/min; Flow rate: 50 sccm) for 3 h. The calcined products were then immersed into 50 mL 1 mol/L HCl acid for 6 h, washed by distilled water and dried in the electric oven at 60 oC. Characterizations and Electrochemical Measurements. The field-emission scanning electron microscope (FESEM, JEOL JSM-7800F; accelerating voltage: 10 kV) equipped with energy dispersive X-ray spectroscopy (EDS) was used to investigate the detailed morphology of hair-based samples. The samples crystalline structure was characterized by XRD using Bruker D8 advance diffractometer with Cu-Kα radiation (λ = 0.15418 nm) and JEM 2010F high-resolution transmission electron microscope (TEM; accelerating voltage: 75 kV). The X-ray photoelectron spectroscopy (XPS) spectra were recorded by Perkin-Elmer model PHI 5600 XPS system with a resolution of 0.3–0.5 eV from a

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monochromatic aluminum anode X-ray source. The Raman spectrum was recorded by a Witech CRM200 spectrometer with 532 nm laser at ambient temperature. The specific surface areas (calculated by using the Brunauer–Emmett–Teller method) and pore size distribution of samples were characterized by N2 adsorption/desorption measurements at 77 K (TriStar II 3020). The electrode mass was determined on a microbalance with an accuracy of 0.01 mg (Ohaus EX125ZH, USA). All working electrodes were fabricated by a conventional slurry-coating method. For details, the derived carbon products were ground into uniform powders, mixed with the carbon black and polymer binder of polyvinylidene fluoride (PVDF) according to a mass ratio of 80:10:10. Then, a moderate amount of N-methyl-2-pyrrolidone (NMP) was dipped into mixed powders and the as-formed mixture was stirred for 8 h to form a homogenous slurry. The slurry was then uniformly pasted onto a copper foil and dried at 80 oC for 12 h in an electrical oven. The as-made film electrode was cut into circular disks (diameter: ~1.2 cm) with a typical mass loading of ~3-4 mg carbon actives per square centimeter. The electrolyte was 1 M LiPF6 dissolved in a 1:1 (v/v) mixture of ethylene carbonate (EC) and diethyl carbonate (DEC). For half-cell testing, the assembly of CR-2032 coin-type cells were carried out in an Ar-filled glovebox (MBraun, Unilab; H2O < 0.1 ppm, O2< 0.1 ppm) with hair-evolved carbon microtubes as the working electrode and a Li metal foil as the counter/reference electrode. While for full-cell testing, the cell assembly procedure is identical except that the commercial LiFePO4 cathode film (purchased from MTI Corporation, USA) was employed as the cathode. The electrode mass matching was performed based on our carbon microtube anode and LiFePO4 cathode behaviors in half-cell testing. Note that before full cells assembly, the anode was attached to a piece of Li metal foils and immersed in the electrolyte (time: 3-5 h) for prelithiation (cutoff voltage: 0.005 V vs. Li/Li+). The specific capacity calculations of full-cell LIBs are based on the total mass of anode and cathode. Galvanostatic testing

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was performed on a NEWARE battery testing system while the other electrochemical measurements were all conducted using an electrochemical workstation (CorrTest CS310). Before testing, all batteries were aged for 10 h.

Results and Discussion The choice of human hair as this paradigm study is given a fact that it is one of common household wastes that can be largely available from barbershops/hair salons (Over hundreds of millions kilograms hair will be generated worldwide every year during haircuts or combings).15-17 From the chemical composition aspect, hairs are made up of distinct amino acids wherein the cysteine (C3H7NO2S) normally takes up the major component (See the circular chart in Figure 1).16 Thereby, the hair-evolved carbons are often rich in multiple heteroatoms that may endow the electrodes with superb electrochemical energy-storage properties due to additional faradic reaction sites and synergistic effects.17 Despite the directly calcined products can serve as the anode for LIBs, their electrode behaviors are far from satisfactory owing to their compact and thick (wall thickness: ~3-5 μm) nature (adverse for the electrolyte infiltration and Li+ diffusion). Besides, their amorphous intrinsic feature, structural defects and inferior electrical conductivity would cause remarkable irreversible capacity losses in initial few cycles and become a bottleneck for the development of high-rate LIBs. To settle above problems, we propose an efficient engineering strategy by catalytically evolving hairs into multiheteroatoms doped GP-CMTs. Such anodic designs own the preferable ionic/electrical conducting behaviors; Li+ can readily commute along porous channels into deep inner places of GP-CMTs while electrons can be preferentially transferred along the graphitic parts. The open-up/porous configuration

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may also render hair-derived anodes with more exposed redox reaction sites, thereby greatly promoting their specific capacity and actives utilization efficiency. Morphological characteristics of ultimate samples are initially detected by scanning electron microscopy (SEM). Figure 2A reveals the GP-CMTs have a central diameter of ~20 μm and well inherit the fibrous architecture. Particularly note that unlike smooth hairs or carbons made via the direct calcination (See SEM images in Figure S1A-B), GP-CMTs are rather rough and evidently possess plenty of pore structures on each CMT surface (Figure 2B). According to the pore-size distribution curve (See the inset in Figure 2B), their pore dimensions are centralized within a wide range from ~1.8 nm to ~22 nm. The existence of such mesoporous structures may offer more redox reaction sites and help to increase the specific capacity and utilization efficiency of electrode actives for Li storage. The cross-sectional SEM image (Figure 2C) furthermore uncovers the tubular wall (thickness: ~3 μm) is quite loose and permeable (by sharp contrast, the directly evolved case is rather dense; See Figure S1C-D). The CMT formation stems from the successive losses of biological substances at the core region of hairs (e.g., pigment, moisture, medulla, etc.) in the thermal treatment. To affirm the promoted graphitization degree, we purposely select the Ni residual-involved samples to observe the catalyst/carbon interfaces by transmission electron microscope (TEM; Figure 2D-E). The highresolution TEM image distinctly shows the well-arranged lattices with a spacing of ~0.34 nm, marching well with the (002) interplanar spacing of carbon. X-ray diffraction (XRD) record (Figure 2F) exhibits a couple of diffraction peaks lying at 22.3o and 43.8o, which are in turn indexed to the (002) and (101) faces of hexagonal carbon (JCPDS Card No. 41-1487) and in support of former TEM analysis. The inset Raman spectroscopy shows the presence of two common fingerprint peaks at the wavenumbers of 1345 and 1590 cm-1, successively in accordance to the defects-caused D band and in-

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plane C-C vibration-induced G band.2 The high ratios of G to D band (IG/ID: ~1.28) once again ensures the good graphitization degree for our evolved products. The X-ray photoelectron spectroscopy (XPS) measurement confirms the existence of C (86.02 %), N (6.56 %), S (4.83 %) and O (2.59 %) elements, implying the successful incorporation of copious heteroatoms into GP-CMTs. The C 1s spectrum (Figure 2G) shows two evident fitting peaks; the main peak (~284.4 eV) stems from graphitic carbon atoms (well-arranged according to the conjugated honeycomb lattice) whereas the other (~286.8 eV) may be related to influences from defects or hetero-atoms.18 As for N 1s spectrum (Figure 2H), three characteristic peaks at ~397.9 eV, ~400.6 eV and ~403.8 eV in turn correspond to pyridinic-, pyrrolicand pyridinic oxide-type N atoms.19 The S 2p spectrum (Figure 2I) shows two peaks at ~163.8 and ~165.0 eV, highly in agreement with the spin orbit coupling and the -C-S- covalent thiophene-S bond, respectively.20 The O 1s spectrum involves two distinct peaks located at ~531.9 and ~533.2 eV (Figure 2J), both of which are indexed to chemical groups in the form of carbonyl or carboxyl.21 Such heteroatoms doping properties may enrich the active places for redox reactions and thus enhance the delivered capacity for LIBs application. For comparison study, we also characterize the CMTs (directly evolved from hairs by calcination at 650 oC in Ar) by XRD and Raman spectroscopy (Figure S2). The diffraction signals of CMTs are rather weak and broad (Figure S2A; the overall peak profile is more close to that of amorphous carbon). In the Raman spectrum of CMTs (Figure S2B), the peak intensity for G-band is definitely lower than that of D-band (IG/ID: ~0.92, far lower than ~1.28 for GP-CMTs). Above detections evidence that CMTs indeed possess a less crystalline (graphitization) degree when compared to our GP-CMTs. The energy dispersive X-ray spectroscopy (EDS) result (Figure S3A) confirms that except for the Cu peak (coming from the background), there are only C, N, O and S (little

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amount) elements involved in GP-CMTs without any other feasible impurities (e.g., Ni), suggesting the total removal of Ni-based component after a careful acid washing treatment. For better understanding the evolution mechanism, the entire fabrication procedures have been thoroughly monitored and analyzed by SEM, XRD and N2 adsorption/desorption measurements (See Figure 3 and 4). To vividly describe the total evolution process of GP-CMTs, the schematics have been displayed in Figure 3A. The top-view SEM observation toward a single hair clearly reveal its fibrous morphology (Figure 3B). On the hair outer surface (cuticle section), there distribute large quantities of shingle-like structures that biologically function as the protective sheath. The cross-sectional SEM image (Figure 3C) reveals the pristine hairs possess a well-defined solid microstructure, with a little specific surface area (SSA) of ~0.81 m2/g (Figure 4A). The XRD detection (bottom curve; Figure 4B) reveals no diffraction peaks are noticed, which is quite normal for non-crystalline biomasses. The first synthetic step is the in-situ growth of NNH nanofilms on hairs. The choice of NNH as the catalytic species is based on former researches that NNH layers can conformally pave on all external surfaces of involved samples regardless of their arbitrary geometric features.22-25 This property can guarantee the homogeneous catalyst distribution, far better than traditional salt-soaking approaches where the asformed catalysts tend to aggregate in local regions.24 SEM observations (Figure 3D-E) toward the intermediate NNH@hairs products clearly confirm the overall hair surface is intimately packaged by NNH nanofilms; in parallel, their SSA value rises to ~33.4 m2/g. In XRD pattern (green curve; Figure 4B), the well-defined diffraction peaks emerge at 25.7 o, 35.8 o, 41.6 o and 67.5 o, which are successively indexed to the facets of (002), (101), (102) and (005) for nickel nitrate hydroxides (JCPDS card no. 22-0752). After calcination, the abundant Ni nanoparticles are then in situ formed, uniformly distributed on hair-derived carbon scaffolds and meantime dig pores. This intermediate evolution stage

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(Ni@GP-CMTs; calcined for only 1 h) has been purposely characterized by SEM (Figure 3F-G). The cross-sectional SEM observation on tubular wall regions (Figure 3G) distinctly demonstrates the nanosized Ni catalysts have drilled into hairs-derived CMTs; the pore size is generally determined by catalyst dimensions whereas the depth relies on the heating time. We also find that once the heating time exceeds 3 h, nearly all microtubes would become porous or even punched. The SSA value for such hybrids is increased to ~127.3 m2/g. Corresponding XRD result (blue curve; Figure 4B) further confirms the successful generation of graphited carbon and metallic Ni (JCPDS card no. 04-0850). The EDS analysis (Figure S3B) reveals nearly all relevant elements (C, N, O, Ni, S) in the evolution procedures are noticed. The mechanism for the transformation of hairs into GP-CMTs with a high graphitization degree is tight associated with the presence of Ni nanocatalysts. Such catalytically active metals can dissolve the amorphous carbon atoms at a low starting temperature of ~600 oC, reduce the conversion reaction barriers and then enable the nucleation/growth of well-arranged carbon layers on all metal surfaces.26-27 Besides, given the amorphous carbons are metastable and energetically higher than graphited ones, this phase-change reaction would preferentially proceed in thermodynamics since the transformation (from the metastable amorphous into graphited carbons) is driven by lowering the energy for overall systems. The phenomenon for Ni nanoparticles movement into CMTs should be attributed to the thermal migration of catalytic metals since the nanosized Ni can readily infiltrate to inner deep regions of CMTs and dissolve more amorphous carbon atoms.26 At last, the final products are harvested by a facile acid wash treatment (the dissolved Ni salts can be totally recycled for NNH@hairs preparation). The Li storage performance of GP-CMTs is primarily studied in coin-type half cells with Li metal as the counter/reference electrode. Figure 5A shows their cyclic voltammetry (CV) curves in a voltage

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window of 0.005-3 V (vs. Li/Li+) under a scan rate of 0.5 mV/s. There are two reduction peaks initially present at ~0.53 and ~1.42 V but disappearing in subsequent scans, which should be associated with irreversible interfacial reactions on GP-CMTs (e.g., electrolytic decomposition) and the formation of solid electrolyte interphase (SEI).4 In all CV scans, there exists a broad cathodic peak at ~0.3 V, attributing to the Li+ intercalation into carbon lattices. Along the continual CV scan, the curve becomes overlapped with each other, suggesting the reversible and stable electrochemical reactions in anode systems. The electrode cyclic endurance and electrochemical stability is evaluated by galvanostatic charge/discharge testing under a current density of ~0.2 A/g (Figure 5B; for comparison, the cyclic record of directly calcined CMTs is also provided). The GP-CMTs exhibits large discharge/charge capacities of ~1006 and ~689 mAh/g at the 1st cycle, with a Coulombic efficiency (CE) of ~68.5% (discharge/charge capacity for counterparts: ~905/413 mAh/g; CE: ~46%). Moreover, such high reversible capacity and CE records are close (or even comparable) to the levels for other state-of-theart biomass-derived anodes with impressive SSAs, hierarchical pore structures and rich heteroatoms co-doped property.28-31 The initial capacity losses may be induced by irreversible factors like the formation of passivation layers on graphitic species, partial electrolyte decomposition and Li+ ions trapping in carbon lattices. Later, the CE immediately rises to a high value of ~99.8% (at the 5th cycle) and keeps still among the following cycles. The capacity originally declines from the starting value to a lowest ~568.7 mAh/g (at the 178th cycle) and then remains at the level of ~574 mAh/g for the next tens of cycles. Later, it is intriguing that there is a continuous and gradual increase in capacity (from the 243th cycle to the end of cycling). At the 1000th cycle, a capacity value up to ~658 mAh/g is still maintained, much higher than that of calcined CMTs (reversible capacity value 2.5 V and rated power: ∼0.5 W) is readily driven by an individual fully charged (−)GP-CMTs//LiFePO4(+), with a long working duration time over 15 min, furthermore implying its great potential in portable battery applications.

Conclusions In summary, we present an efficient engineering way to transform hair wastes into multiple heteroatoms doped GP-CMTs for the anode of LIBs. As fully confirmed, the uniform and intimate encapsulation of NNH nanofilms on all hair external surface indeed plays a critical catalytic role in enabling the rapid biomass graphitization at a moderate temperature (~650 oC) and meantime helping

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to dig deep pores on each GP-CMT, yielding abundant and convenient channels for Li+ diffusions. When applied as anode materials of LIBs, such GP-CMTs can exhibit superb anodic behaviors to directly calcined products, including remarkable reversible capacities (Max.: ~689 mAh/g), greatly improved actives utilization efficiency, prolonged cyclic lifespan (no capacity fading in 1000 cycles) and prominent rate capabilities (retaining a Max. capacity of ~387 mAh/g even at 6 A/g). Synergistic effects between heteroatoms and unique intrinsic texture features may be major reasons to account for the superior anodic behaviors of GP-CMTs. Our work proposes a smart engineering way for the evolution of biomass wastes into advanced carbon anode substitutes for sustained LIBs applications.

Acknowledgements The authors gratefully acknowledge financial support from National Natural Science Foundation of China (11604267, 51802269), Chongqing Natural Science Foundation (cstc2016jcyjA0477) and the Fundamental Research Funds for the Central Universities (XDJK2018C005, SWU115027, and SWU115029).

Supporting Information SEM observations, XRD and Raman patterns of directly evolved CMTs; EDS spectra for GP-CMTs and Ni@GP-CMTs; EIS spectra and SEM/TEM observations on cycled GP-CMTs; Galvanostatic cyclic record for full cells.

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Sustainable Anodes for Li-Ion Batteries. Energy Environ. Sci. 2014, 7, 2670−2679, DOI 10.1039/C4EE00602J. 3. Shen, F.; Zhu, H.; Luo, W.; Wan, J.; Zhou, L.; Dai, J.; Zhao, B.;Han, X.; Fu, K.; Hu, L. Chemically Crushed Wood Cellulose Fiber towards High-Performance Sodium-Ion Batteries. ACS Appl. Mater.Interfaces 2015, 7, 23291−23296, DOI 10.1021/acsami.5b07583. 4. Xie, D.; Xia, X. H.; Xia, Y.; Tang, W.; Zhong, Y.; Wang, Y.; Wang, D.; Wang, X. L.; Tu, J. P. Novel Carbon Channels From Loofah Sponge For Construction of Metal Sulfide/Carbon Composites with Robust Electrochemical Energy Storage. J. Mater. Chem. A 2017, 5, 7578–7585, DOI 10.1039/C7TA01154G. 5. Ma, Q.; Yu, Y.; Sindoro, M.; Fane, A. G.; Wang R.; Zhang, H. Carbon-Based Functional Materials Derived from Waste for Water Remediation and Energy Storage. Adv. Mater. 2017, 29, 1605361– 1605380, DOI 10.1002/adma.201605361. 6. Qian, W. J.; Sun, F. X.; Xu, Y. H.; Qiu, L. H.; Liu, C. H.; Wang, S. D.; Yan, F. Human Hair-Derived Carbon Flakes For Electrochemical Supercapacitors. Energy Environ. Sci. 2014, 7, 379–386, DOI 10.1039/C3EE43111H. 7. Ou, J.; Zhang, Y.; Chen, L.; Yuan, H.; Xiao D. Heteroatom Doped Porous Carbon Derived from Hair as An Anode with High Performance for Lithium Ion Batteries. RSC Adv. 2014, 4, 63784– 63791, DOI 10.1039/C4RA12121J. 8. Sun, G.; Zhou, L.; Li, J.; Tang, J.; Wang, Y. Human Hair-Derived Graphene-Like Carbon Nanosheets To Support Pt Nanoparticles For Direct Methanol Fuel Cell Application. RSC Adv. 2015, 5, 71980-71987, DOI 10.1039/C5RA12768H. 9. Wang, S.; Xiao, C.; Xing, Y.; Xu, H.; Zhang, S. Carbon Nanofibers/Nanosheets Hybrid Derived From Cornstalks as A Sustainable Anode for Li-Ion Batteries. J. Mater. Chem. A 2015, 3, 6742– 6746, DOI 10.1039/C5TA00050E. 10. Zhu, C.; Akiyama, T. Cotton Derived Porous Carbon via An MgO Template Method for High Performance Lithium Ion Battery Anodes. Green Chem. 2016, 18, 2106–2114, DOI 10.1039/C5GC02397A. 11. Zhang, X.; Zhong, Y.; Xia, X. H.; Xia, Y.; Wang, D.; Zhou, C.; Tang, W.; Wang, X.; Wu, J.; Tu, J. P. Metal-Embedded Porous Graphitic Carbon Fibers Fabricated from Bamboo Sticks as a Novel

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Cathode for Lithium–Sulfur Batteries. ACS Appl. Mater. Interfaces 2018, 10, 13598–13605, DOI 10.1021/acsami.8b02504. 12. Fromm, O.; Heckmann, A.; Rodehorst, U. C.; Frerichs, J.; Becker, D.; Winter M.; Placke, T. Carbons from Biomass Precursors as Anode Materials for Lithium Ion Batteries: New Insights into Carbonization and Graphitization Behavior and into Their Correlation to Electrochemical Performance. Carbon 2018, 128, 147–163, DOI 10.1016/j.carbon.2017.11.065. 13. Lu H.; Zhao X. S. Biomass-Derived Carbon Electrode Materials for Supercapacitors. Sustainable Energy Fuels, 2017, 1, 1265–1281, DOI 10.1039/C7SE00099E. 14. Tyagi, A.; Tripathi, M.; Gupta, R. Recent Progress In Micro-Scale Energy Storage Devices and Future Aspects. J. Mater. Chem. A 2015, 3, 22507–22541, DOI 10.1039/C5TA05666G. 15. Velasco, M.; Dias, T.; Freitas, A.; Vieira, N.; Pinto, C.; Kaneko, T. M.; Baby, A. R. Hair Fiber Characteristics and Methods to Evaluate Hair Physical and Mechanical Properties. Braz. J. Pharm. Sci. 2009, 45, 153–162, DOI 10.1590/S1984-82502009000100019. 16. Yu, Y.; Yang, W.; Wang, B.; Meyers M. Structure and Mechanical Behavior of Human Hair. Mater. Sci. Eng. C Mater. Biol. Appl. 2017, 73, 152–163, DOI 10.1016/j.msec.2016.12.008. 17. Zheng, F.; Liu, D.; Xia, G.; Yang, Y.; Liu, T.; Wu, M.; Chen, Q. Biomass Waste Inspired NitrogenDoped Porous Carbon Materials as High-Performance Anode for Lithium-Ion Batteries. J. Alloys Compd. 2017, 693, 1197–1204, DOI 10.1016/j.jallcom.2016.10.118. 18. Mai, L. Q.; Minhas-Khan, A.; Tian, X.; Hercule, K.; Zhao, Y.; Lin, X.; Xu X. Synergistic Interaction Between Redox-Active Electrolyte And Binder-Free Functionalized Carbon For Ultrahigh Supercapacitor Performance. Nat. Commun. 2013, 4, 2923, DOI 10.1038/ncomms3923. 19. Dong, Y.; Pang, H.; Yang, H.; Jiang, J.; Chi, Y.; Yu, T. Nitrogen-Doped Carbon-Based Dots Prepared by Dehydrating EDTA with Hot Sulfuric Acid and Their Electrocatalysis for Oxygen Reduction Reaction. RSC Adv. 2014, 4, 32791-32795, DOI 10.1039/C4RA06594H. 20. Ai, W.; Luo, Z.; Jiang, J.; Zhu, J.; Du, Z.; Fan, Z.; Xie, L.; Zhang, H.; Huang, W.; Yu, T. Nitrogen and Sulfur Codoped Graphene: Multifunctional Electrode Materials for High-Performance Li-Ion Batteries and Oxygen Reduction Reaction. Adv. Mater. 2014, 26, 6186-6192, DOI 10.1002/adma.201401427.

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Figures and Figure Captions:

Figure 1. Schematics displaying the hair compositions, major issues for conventional hairscalcined products and unique merits of our designed GP-CMTs in LIBs applications.

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Figure 2. (A-B) Top-view and (C) cross-sectional SEM observations on GP-CMTs. (D-E) TEM observations on the catalyst/carbon interfaces of our evolved samples. (F) XRD pattern (inset: Raman spectrum) and (G-J) XPS spectra of GP-CMTs (G: C1s; H: N1s; I: S2p; J: O1s).

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Figure 3. (A) The schematic showing the overall evolution procedures. SEM monitoring on samples at distinct evolution stages (B-C: pristine natural hairs; D-E: NNH@hairs; F-G: Ni dots@GP-CMTs).

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Figure 4. (A) N2 adsorption/desorption isotherms and (B) XRD pattern of samples at distinct evolution stages.

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Figure 5. (A) CV plots, (B) galvanostatic cyclic behavior, (C) corresponding charge/discharge profiles and (D) programmed cyclic records of GP-CMTs under a half-cell testing system. (E) A typical galvanostatic charge/discharge plot (inset: the schematic for the full-cell configurations) and (F) rate performance of as-assembled (−)GP-CMTs//LiFePO4(+) (Inset: optical image displaying a single cell can drive a green LED light).

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Table of Content

Synopsis: Smart evolution of hair wastes into graphitic, porous and multi-heteroatoms co-doped carbon microtube anodes has been achieved for sustained Li-ion batteries.

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Hairs

Direct Carbonization

i. ii. iii.

Amorphous, thick and dense; Poor solid-state Li+ diffusion; Low actives utilization.

Our configurations: Better Actives Utilization Deep Pores

Li+ “Dead” Capacity

~3-5 μm

Preferable Conducting Graphitized

Rich in deep pores

Figure 1. ACS Paragon Plus Environment

Li+

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(B)0.15

(C)

0.10

3

-1

-1

dV/dQ (cm g nm )

(A)

0.05

~3 μm

0.00 1

10

Pore Width (nm)

5 μm

100

2 μm

500 nm

G Band

Graphited Carbon

Intensity (a.u.)

(E) Intensity (a.u.)

(D)

0.34 nm

Residual Ni

D Band

900

1200

1500

1800 -1

2100

Wavenumber (cm )

(002) 5 nm

10

20

30

40

50

60

2 Theta

C1s

280

284

288

Binding Energy (eV)

292

396

400

404

408

Intensity (a.u.)

Intensity (a.u.) 392

O1s

S2p

N1s Intensity (a.u.)

Intensity(a.u.)

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 29 30 31 32 33 34 35 36 37 38 39 40 41

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155

Binding Energy (eV)

160

165

Binding Energy (eV)

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Figure 2.

170

525

530 535 540 Binding Energy (eV)

70

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ACS Sustainable Chemistry & Engineering Ni Salts Recycling

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 29 30 31 32 33 34 35 36 37 38 39 40 41

NNH Layers

Pores Hollow

Solid

Solid

Acid Wash Solution Method

(B)

Heating

(D)

(F)

Ni Dots@GP-CMTs

10 μm

5 μm

(C)

1 μm

10 μm

(G)

(E) NNH Layers

Solid

10 μm

1 μm ACS Paragon Plus Environment Figure 3.

Ni Catalysts

0.5 μm

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(002)

400

Ni(OH)2

Ni

Carbon

(101)

306.9 m2 /g

Intensity (a.u.)

GP-CMTs

-1

300 3

V/cm g

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 29 30 31 32 33 34 35 36 37 38 39 40 41

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GP-CMTs

200

127.3 m2 /g Ni@GP-CMTs

100

33.4 m2 /g

(111) (200) Ni@GP-CMTs (002) (101) (102)

(005) NNH@Hairs

NNH@Hairs

0

0.81 m2 /g

Hairs

0.0

0.2

0.4

0.6

0.8

Hairs

1.0

20

P/P0

30

40

2 Theta

Figure 4.

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50

60

70

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1200

2nd

100

5th

-0.5

1st -1.0 -1.5 0.0

0.5

1.0

1.5

2.0

2.5

800

Directly calcined CMTs

0

200

400 200

800

0

0

50 100 150 200 250 300 350 400

Cycles

2nd 1st

1

0 0

200

400 600 800 Capacity (mAh/g)

1000

200

0.15 A/g

-1

3.6 3.4 3.2

LiFePO4 (+)

3.0 2.8

Directly calcined CMTs

2

1000

3.8

Voltage (V)

600

0

400 600 Cycle Number

4.0

GP-CMTs

60

20

200

4.2

800

80

40

400

Voltage (V) 1000

~658 mAh/g

GP-CMTs

600

0

3.0

Charge Discharge

100th 500th 1000th 50th

3

Voltage (V)

0.0

1000

Coulombic Efficiency (%)

th

Capacity (mAh g )

10 20th

Capacity (mAh/g)

Current (mA)

0.5

Capacity (mAh/g)

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 29 30 31 32 33 34 35 36 37 38 39 40 41

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This Anode (-)

2.6 0

50

100

150

200

250

Capacity (mAh/g)

Figure 5.

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300

0.15 A/g

150

0.3 A/g

100

0.15 A/g 0.45 A/g 0.75 A/g 1.2 A/g 2.4 A/g

50 0

0

50

100

150

Cycle Number

200

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Table of Content NNH Layers

Solid

Solid

Solution Method

Heating

Ni Salts Recycling

Better Actives Utilization Deep Pores Preferable Conducting Li+ Graphitized

LiFePO4 (+)

Acid Wash

Rich in deep pores

This Anode (-)

Synopsis: Smart evolution of hair wastes into graphitic, porous and multi-heteroatoms co-doped carbon microtube anodes has been achieved for sustained Li-ion batteries.

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