General Preparation of Three-Dimensional Porous Metal Oxide Foams

Jun 20, 2016 - *E-mail: [email protected]., *E-mail: [email protected]. ... coating have been synthesized via a general surfactant-assisted template me...
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General Preparation of Three-Dimensional Porous Metal Oxide Foams Coated with Nitrogen-Doped Carbon for Enhanced Lithium Storage Ke Lu,† Jiantie Xu,‡ Jintao Zhang,*,† Bin Song,§ and Houyi Ma*,† †

Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China ‡ Department of Macromolecular Science and Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States § Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, China S Supporting Information *

ABSTRACT: Porous metal oxide architectures coated with a thin layer of carbon are attractive materials for energy storage applications. Here, a series of porous metal oxide (e.g., vanadium oxides, molybdenum oxides, manganese oxides) foams with/ without nitrogen-doped carbon (N−C) coating have been synthesized via a general surfactant-assisted template method, involving the formation of porous metal oxides coated with 1-hexadecylamine (HDA) and a subsequent thermal treatment. The presence of HDA is of importance for the formation of a porous structure, and the successive pyrolysis of such a nitrogen-containing surfactant generates nitrogendoped carbon (N−C) coated on the surface of metal oxides, which also provides a facile way to adjust the valence states of metal oxides via the carbothermal reduction reaction. When used as electrode materials, the highly porous metal oxides with N−C coating exhibited enhanced performance for lithium ion storage, thanks to the unique 3D structures associated with highly porous structure and thin N−C coating. Typically, the porous metal oxides (V2O5, MoO3, MnO2) exhibited discharge capacities of 286, 303, and 463 mAh g−1 at current densities of 30 and 100 mA g−1, respectively. In contrast, the metal oxides with low valences and carbon coating (VO2@N−C, MoO2@N−C, and MnO@N−C) exhibited improved capacities of 461, 613, and 892 mAh g−1. The capacity retentions of about 87.5, 80.2, and 85.0% for VO2@N−C, MoO2@N−C, and MnO@N−C were achieved after 600 cycles, suggesting the acceptable cycling stability. The present strategy would provide general guidance for preparing porous metal oxide foams with enhanced lithium storage performances. KEYWORDS: porous structure, metal oxide foam, nitrogen-doped carbon, lithium storage, surfactant

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INTRODUCTION

Despite various synthesis strategies that have been developed so far, templates are commonly involved, which then have to be removed without damaging the inorganic shell.13−17 For example, mesoporous metal oxides (e.g., TiO2, MnOx, and Fe2O3) with a highly ordered pore structure have been synthesized by impregnating mesoporous silica templates with an aqueous solution containing metal ion precursors, and successive thermal treatment. Finally, the silica template has to be removed to obtain a replica mesoporous structure.16,17 The synthesis procedures are relatively complicated and often involve the template-removing step. Therefore, it is highly desirable to develop simple and efficient methods to fabricate porous metal oxides for LIB applications.

Metal oxides have received more attention in energy storage/ conversion systems, especially in lithium ion batteries (LIBs) and supercapacitors (SCs), due to their high theoretical capacities/energy densities.1,2 However, these metal oxides as active electrode materials for LIBs still suffer from low rate capability and/or poor cycling stability.3−5 To address these critical issues, many efforts have been devoted to the morphology and structure modifications of metal oxides.6,7 The rational design of metal oxide nanostructures with threedimensional (3D) porous and/or hollow structures would provide effective ways to enrich the active sites for enhanced lithium ion storage. Furthermore, the porous structures would generate plenty of free spaces for easy alleviation of volume expansion/extraction during the lithiation/delithiation process, thereby leading to high capacity, good rate capacity, and long cycling life.8−12 © XXXX American Chemical Society

Received: April 18, 2016 Accepted: June 20, 2016

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DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

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electrochemical workstation was used to measure the electrochemical impedance spectroscopy (EIS) from 100 kHz to 100 mHz with an ac amplitude of 5 mV.

The in situ production of gas bubbles has been used to prepare porous metal oxides18 and porous graphene19 without complex template-removal steps. Herein, a series of 3D porous metal (e.g., V, Mo, Mn) oxide foams with nitrogen-doped carbon coating (namely, metal oxide@N−C) were successfully prepared by a general surfactant-assisted blowing process in the presence of a long-chain alkylamine surfactant (e.g., 1hexadecylamine), followed by thermal treatment. The surfactant could be carbonized to uniform nitrogen-doped carbon (N−C) coating while the valences of inside metal oxides are simultaneously modulated. The lithium storage performances of these metal oxide@N−C composite electrodes were investigated for the promising LIB application. Remarkably, these composite materials delivered enhanced performance for lithium ions storage. The enhanced performance of metal (V, Mo, Mn) oxide@N−C would be contributed to their unique 3D porous structures in which the metal oxides are strongly wrapped inside the N−C films and then effectively utilized during the discharge−charge process while the outside N−C film not only enhances the electronic conductivity of the composite but also accommodates the volume change. Furthermore, the valence modulation of the metal oxide is also of importance for the good performance due to the profound effects of the oxidation states. Therefore, the present method is highly desirable to enhance the lithium storage performance via the rational preparation of porous 3D metal oxide architectures.

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RESULTS AND DISCUSSION Scheme 1 demonstrates the preparation process of metal (V, Mo, Mn) oxides@N−C. Initially, the mixed slurry of metal Scheme 1. Schematic Illustration for the Preparation of Macroporous Metal Oxide@N−C Foamsa

a

Initially, metal oxide powder and 1-hexadecylamine (HDA) are mixed in acetone. The reaction is initiating by introducing hydrogen peroxide. Along with the decomposition of hydrogen peroxide, the release of gas generated leads to the formation of porous metal (e.g., V, Mo, Mn) oxides coated with HDA (metal oxide−HDA foam). The porous metal oxide foams with nitrogen-doped carbon (N−C) coating (metal oxide@N−C foam) are obtained via thermal treatment at 400 °C in N2 atmosphere

oxide and 1-hexadecylamine (HDA) in acetone was obtained under sonication. To initiate the blowing process, hydrogen peroxide was introduced into the reaction system. Along with the gas generated from the decomposition of hydrogen peroxide, the progressive dissolution of metal oxide and the decomposition of the unstable species formed in the solution give rise to the formation of porous metal (e.g., V, Mo, Mn) oxides in the presence of a surfactant.18,20 Finally, the metal (e.g., V, Mo, Mn) oxides with/without N−C coating are obtained via heat treatment at 400 °C in N2 or air atmosphere, respectively. On the basis of the blowing process, the porous metal oxides have been prepared successfully. Figure 1a shows a scanning electron microscopy (SEM) image of the foamlike molybdenum oxide with a 3D porous architecture with interconnected skeletons and large pores (∼20−500 μm). Similar porous structures for vanadium oxide (Figure 1b) and manganese oxide (Figure S1) were also prepared. It is worth noting that the surfactant plays an important role for the formation of porous structure. Along with the release of gas, the formation of bubbles in the presence of HDA makes the blowing process happen (insets, Figure 1a and b), finally leading to the formation of the porous structures.9,21 In the absence of a surfactant, the blowing process is not able to be achieved (Figure S2, additional experiment). Besides, it is evident that the surfactant would be coated on the surface of metal oxides after the blowing process according to the Fourier transform infrared spectroscopy (FTIR) (Figure 3).22 The surfactant as a reservoir of carbon precursor was then carbonized into the uniform carbon coating (Figures 1c and d and S1b−e). The high-resolution transmission electron microscopy (HRTEM) images further reveal the lattice fringes with spacing of 0.28 (inset, Figure 1c) and 0.37 nm (Figure 1d) for the samples, which can be well ascribed to the (102) and (110) planes of MoO2 and VO2, respectively. Moreover, the energy-dispersive X-ray (EDX) elemental mappings of VO2@N−C foam (Figure 1e) display the well-distributed V, C, and N through the VO2@

METHODS AND EXPERIMENTAL SECTION

Materials preparation. Initially, porous metal oxide foams were prepared according to a modified blowing method9 followed by thermal treatment. Typically, vanadium oxide (V2O5) powder (0.5 g) was added into a solution of a long-chain alkylamine surfactant (1hexadecylamine, C16H33NH2; 0.08 g) in acetone (3 mL). Then, an aqueous solution of hydrogen peroxide (15 mL, 30%) was mixed with the resulting pasty material. A voluminous foam was gradually formed along with the decomposition of hydrogen oxide. The obtained foam was calcined at 400 °C for 1 h in N2 flow. For comparison, V2O5 foam was prepared by annealing the obtained foam at 400 °C in air for 20 min. The same procedure was used to prepare other metal oxide foams. Materials characterization. The crystal structure and phase purity of the products were determined by X-ray diffraction (XRD) on a Bruker D8 advanced X-ray diffractometor equipped with Cu Kα radiation. X-ray photoelectron spectroscopy (XPS) was recorded on an ESCALAB 250 X-ray photoelectron spectrometer. The Raman spectra were collected on LabRAM HR 800 system using a 514 nm laser. Scanning electron microscopy (SEM) images were measured on a Hitachi X650 electron microscope. Transmission electron microscopy (TEM) images were presented on a JEOL JEM-2100 microscope. Fourier transform infrared spectroscopy (FTIR) measurements were performed with a Bruker TENSOR27 infrared spectrophotometer using the KBr tablet method. Electrochemical characterization. The electrochemical measurements were carried out at room temperature using CR2016 cointype half cells. The working electrodes were composed of metal oxide foam (80%), acetylene black (15%), and polyvinylidene fluoride (PVDF) (5%). The composite electrode (∼1.5 mg cm−2) was loaded onto the current collector, and the specific capacity was calculated based on the mass of the active materials. Lithium foil was coupled with the working electrode by using 1 M LiPF6 in ethyl carbonate/ dimethyl carbonate (EC/DEC) (1:1 v/v), the electrolyte. Polypropylene membrane was used as the separator. Cyclic voltammetry (CV) was performed on a CHI 660D electrochemical workstation at a scan rate of 0.1 mV s−1. The charge and discharge curves were recorded on a Land CT2001A battery test system. A Zahner IM6 B

DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

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ACS Applied Materials & Interfaces

Figure 1. SEM (a, b) and HRTEM (c, d) images of MoO2@N−C (a, c) and VO2@N−C (b, d). Insets are the digital photo images (a, b) of metal oxide foams formed in the presence of HDA and the enlarged TEM image (c). TEM image with the corresponding element mapping images of VO2@N−C (e).

N−C composite. The uniform nitrogen element distributed through the carbon shell would be attributed to the carbonization of N-containing surfactant (HDA). According to the thermal gravity analysis (Figure S3), the carbon content is estimated to be around 10, 10, and 9% for VO2@N−C, MoO2@N−C, and MnO@N−C, respectively. The carbon coating is highly desirable to improve the electrical conductivity.23−26 In the present case, the rationally designed metal oxides with porous structure and carbon coating would facilitate the rapid migration of Li ions and accommodate the volume expansion.27−29 Thus, enhanced performance would be achieved for Li storage. X-ray diffraction (XRD) analyses were used to identify the phases of the as-prepared porous metal oxides (Figure 2a−c). As can be seen, the XRD pattern of the V2O5−HDA foam after calcination at 400 °C for 20 min in air (Figure 2a) is wellindexed to the orthorhombic V2O5 phase (JCPDS no. 411426). The sample obtained in N2 atmosphere (Figure 2a) is indexed to VO2 (JCPDS no. 31-1438) with a monoclinic structure. Although no XRD peaks for carbon are observed, the presence of D and G bands in Raman spectroscopy (Figure 3) indicates the formation of graphitic carbon in the composite, consistent with TEM and EDX results. The results confirmed the formation of the monoclinic VO2 coated with nitrogendoped carbon in inert atmosphere. During the thermal treatment, V2O5 was gradually reduced to VO2 due to the carbothermic reduction between the HDA-derived carbon and V2O5 in inert atmosphere, hence leading to the formation of final VO2@N−C composites. However, only V2O5 was left along with the thermal decomposition of HDA in air. The same phenomenon is also observed for the samples of molybdenum oxides and manganese oxides (Figure 2b, c, f, and g). X-ray photoelectron spectroscopy (XPS) provides further insights into the element oxidation states of metal oxide@N−C (Figures 2d−g and S4). The XPS survey spectroscopy (Figure S4a) displays the presence of V, O, C, and N for VO2@N−C.

Figure 2. XRD patterns of as-synthesized metal oxides (a−c). Highresolution XPS spectra of V2p for V2O5 foam and VO2@N−C (d), N1s for VO2@N−C (e), Mo3d for MoO2@N−C (f), and Mn2p for MnO@N−C (g).

Figure 3. Raman (a−c) and FTIR (d−f) spectra of different metal oxides.

C

DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces The high-resolution XPS N1s of VO2@N−C (Figure 2e) is fitted into three component peaks centered at about 398.5, 400.5, and 401.5 eV, corresponding to pyridinic N, pyrrolic N, and quaternary N, respectively. This further confirms the formation of nitrogen-doped carbon frameworks in the VO2@ N−C. The high-resolution XPS V2p reveals that the binding energy located at 516.5 and 523.6 eV is well-ascribed to the chemical state of V(IV),30 rather than that of V2O5 located at 517.8, 525.3 eV for V(V).31 The results indicated that V2O5 was gradually reduced to VO2 due to the carbothermic reduction between the HDA-derived carbon and V2O5 in an inert N2 atmosphere. The same phenomenon is also observed for the molybdenum oxides (MoO3 and MoO2@N−C) and manganese oxides (MnO2 and MnO@N−C), as evidenced by XRD (Figure 2b and c), Raman (Figure 3), and XPS (Figures 2f and g and S4). Specifically, the binding energies of Mo 3d5/2 and Mo 3d3/2 for MoO2@N−C are centered at 229.5 and 232.8 eV, respectively. The additional peaks at 231.9 and 235.4 eV could be ascribed to Mo(VI) 3d5/2 and 3d3/2 of MoO3, possibly arising from the slight surface oxidation of the metastable MoO2 in air.11 For MnO@N−C, the binding energies of Mn 2p1/2 and Mn 2p3/2 are located at around 652.8 and 641.3 eV, respectively (Figure 2g).32 Overall, the similar results for all metal oxides@N−C or metal oxides demonstrate that the incorporation of the surfactant-assisted blowing process with a subsequent thermal treatment is highly universal to synthesize porous metal oxides with desirable valence states, as well as carbon coating. The same Raman spectra (Figure 3a−c) were observed for the samples before and after thermal treatment in air. The peaks are ascribed to the Raman shifts caused by metal oxides. However, the presence of characteristic D band and G band located at around 1350 and 1590 cm−1 suggested the pyrolysis of HDA to carbons in inert atmosphere. Thus, the metal oxide foam−surfactant can be transformed into the desired porous metal oxides via thermal treatment in N2 flow. As shown in FTIR (Figure 3d−f), the characteristic peaks located at ∼2848 and 2912 cm−1 are ascribed to the vibration response of the C− H bonds in HDA and disappeared after thermal treatment, suggesting the presence of HDA on the surface of metal oxides after the blowing process. In the case of the FTIR spectrum of vanadium oxide (Figure 3d), for example, the vibrational band at 535 cm−1 can be attributed to the vibrational bands of V−O (VO2@N−C) and the band centered at 830 cm−1 corresponds to the V−O−V bending vibration (V2O5). The signals of carbon and nitrogen could also be clearly identified in the mapping images (Figure 1e). The above results demonstrate that the incorporation of the surfactant-assisted blowing process with thermal treatment is highly universal to synthesize porous metal oxides with desirable valence states and carbon coating. The electrochemical properties of porous metal oxides@N− C for lithium storage were investigated. Three consecutive cyclic voltammetry (CV) curves of the N-doped carbon-coated porous metal oxide foams at a scan rate of 0.1 mV s−1 are shown in Figure 4a−c. As can be seen, the identical CV curves for all the composites indicate their good reversibility in the electrochemical processes. For VO2@N−C, the well-defined cathodic/anodic peak is due to the intercalation/deintercalation of Li+, corresponding to the formation/deformation of LixVO2 (Figure 4a).33 In contrast, multipeaks (Figure S6a) for pure V2O5 foam are observed due to the higher V(V) for V2O5 than V(IV) for VO2 experiencing additional phase transitions.33,34

Figure 4. Cyclic voltammogram curves of VO2@N−C (a), MoO2@ N−C (b), and MnO@N−C (c) at a scan rate of 0.1 mV s−1. Galvanostatic charge/discharge curves of VO2@N−C (d), MoO2@ N−C (e), and MnO@N−C (f).

Figure 4d shows the charge/discharge profiles of VO2@N−C at 30 mA g−1 over the voltage range of 2−3.8 V. A pair of charge/ discharge plateaus at about 2.53 and 2.47 V is observed in the first cycle and is highly reversible in the following cycles, indicating the good reversibility of VO2@N−C. To optimize the performance for Li storage, the VO2@N−C samples were prepared by changing the ratio of vanadium oxide to HDA (Figure S5). It can be seen that the largest capacity for Li storage is achieved at a ratio of 6.25. On the basis of the representative cycles (1st, 5th, 100th, and 200th) at 30 mA g−1, the initial discharge capacity based on the total mass loading of VO2@N−C is ∼461 mAh g−1 with an initial Coulombic efficiency (CE) of 97.8%, which is significantly superior to that of V2O5 foam (286 mAh g−1 and 96.2%) (Figure S6b). The reversible discharge capacity of VO2@N−C electrode still remains 469, 415, and 348 mAh g−1 after 5, 100, and 200 cycles, respectively. The CV curves of the MoO2@N−C and MoO3, and MnO@ N−C and MnO2, are shown in Figures 4b and c and S6b and c. For MoO2@N−C (Figure 4b), in the first cycle, a couple of reduction peaks for Li insertion were observed at 1.52/1.25 V. The corresponding oxidation peaks for Li extraction were observed at 1.48 and 1.78 V, indicating a good reversibility for MoO2@N−C.35 The overlapped redox peaks suggest the highly reversible phase transitions in the subsequent cycles. Furthermore, the initial discharge capacity of MoO2@N−C at a current density of 100 mA g−1 is 856 mAh g−1 with a CE of ∼69%. It should be noted that the obvious capacity loss of the initial cycle for MoO2@N−C is mainly due to the trapping of lithium in the lattice of MoO2 and/or the formation of a solid electrolyte interface (SEI).35 However, the reversible discharge capacities were 581, 493, and 418 mAh g−1 after 100, 200, and 300 cycles, respectively, suggesting the acceptable capacity retention from the second cycle onward. On the other hand, for D

DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

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100 mA g−1 after 40 cycles, the capacity with a retention of 98.8% was 881 mAh g−1. The results (Figures 5 and S8 and Tables S1 and S2) revealed that the macroporous crystalline metal oxide@N−C foam materials exhibited good high-rate performance and cycling reversibility. The excellent electrochemical performance would be contributed to their unique 3D interconnected macroporous structure and the thin N-doped carbon coating. As demonstrated in Figure 5b, the 3D hierarchical macroporous framework allows the electrolyte easy accessibility to the inner surface with a rapid diffusion of lithium ions. The porous structure can also provide free spaces to accommodate the volume changes for repeated cycling test.8,10 Furthermore, the N-doped carbon coating layer on the surfaces of 3D metal oxides also facilitates rapid electron transport with low charge-transfer resistance (Figure S9).38 The long-term cycling stabilities of metal oxides@N−C are shown in Figure 5c. As can be seen, the reversible capacity of VO2@ N−C is 351.5 mAh g−1 after 600 cycles with a capacity retention of ∼87.5% (vs 80.2% and 85.0% capacity retention for the second cycles of MoO 2 @N−C and MnO@N−C, respectively).

the MnO@N−C (Figure 4c), the cathodic peak at ∼0.1 V in the first cycle disappears in successive cycles due to the formation of SEI film and the reduction of Mn2+ to Mn0.36 Because of the irreversible phase transformation associated with the formation of Li2O and Mn, the cathodic peak was shifted to higher potential (0.43 V, 0.36 V) during subsequent cycles.37 In the anodic sweep, the main oxidation peak at 1.22 V could be attributed to the oxidation of Mn0 to Mn2+.36 According to the discharge/charge curves (Figures 4f and S6f), an initial discharge capacity of 1265 mA g−1 for MnO@N−C is achieved at a current density of 100 mA g−1, which is much larger than that of MnO2 foam (840 mAh g−1). Similar to the case of MoO2@N−C, the initial CE is only 68% for MnO@N−C and 51% for MnO2, due to the irreversible formation of a SEI layer. However, the nearly overlapped charging/discharging curves rendered a high capacity of 847 mAh g−1 for MnO@N−C after 200 cycles (93.2% capacity retention for the second cycle), higher than that for MnO2 (374 mAh g−1 and 74.0%), indicating the better reversibility of MnO@N−C. Additionally, the capacity of MnO@N−C is also larger than those of pure MnO (Figure S7), suggesting the important role of carbon coating. The rate capability of the VO2@N−C, MoO2@N−C, and MnO@N−C was measured at various current densities (Figure 5a). The detailed capacities of metal oxides@N−C are listed in

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CONCLUSION In summary, a series of porous metal oxide (e.g., vanadium oxides, molybdenum oxides, manganese oxides) foams with/ without nitrogen-doped carbon coating were synthesized via a simple and efficient surfactant-assisted blowing process followed by a subsequent thermal treatment. The surfactant is of importance for the formations of porous metal oxides and the conductive nitrogen-doped carbon layer. When used as electrode materials for Li storage, the discharge capacities of 461 mAh g−1 for VO2@N−C and 286 mAh g−1 for V2O5 foam have been achieved. The carbon-coated molybdenum oxide and manganese oxide foams also exhibited enhanced capacities for Li storage. Taking advantages of the uniform N-doped carbon coating and the hierarchical porous structure, the cycling stability and rate performance of the metal oxides were markedly enhanced. The present constructive strategy can be extended to prepare other metal oxide foams and will provide general guidance for the development of high-performance electrode materials.

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Figure 5. Rate capabilities of VO2@N−C, MoO2@N−C, and MnO@ N−C at various current densities (a). Schematic illustration of 3D ionic and electronic transport pathways (b). Cycling performance and Coulombic efficiency of VO2@N−C at 100 mA g−1, MoO2@N−C at 500 mA g−1, MnO@N−C at 500 mA g−1 (c).

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.6b04587. SEM image, XPS pattern, and electrochemical performance and EIS spectra of porous V2O5, MoO3, and MnO2 (PDF)

Table S1. As shown in Figure 5a and Table S1, the specific capacity of VO2@N−C electrode is 461 mAh g−1. No obvious capacity decay is observed in the successive charge/discharge cycles at the same current density. When the current was restored to 30 mA g−1 after 60 cycles, the capacity of VO2@N− C was recovered to 98.1% of the initial specific capacity. For the MoO2@N−C electrode, when the current density was increased by 10 times (100 to 1000 mA g−1), the reversible capacity retention was ∼75.8%, exhibiting a good high-rate performance. Moreover, when the current was restored to 100 mA h g−1 after 40 cycles, ∼99.5% of the initial discharge capacity (608 mA h g−1) was recovered. For the MnO@N−C electrode, the capacity retention was ∼75.6% at a high current density of 1000 mA g−1. When the current density went back to

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (21373129, 21503116). E

DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

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(20) Alonso, B.; Livage, J. Synthesis of Vanadium Oxide Gels from Peroxovanadic Acid Solutions: A 51V NMR Study. J. Solid State Chem. 1999, 148, 16−19. (21) Piquemal, J. Y.; Briot, E.; Brégeault, J. M. Preparation of Materials in the Presence of Hydrogen Peroxide: From Discrete or “Zero-Dimensional” Objects to Bulk Materials. Dalton Trans. 2013, 42, 29−45. (22) Durupthy, O.; Jaber, M.; Steunou, N.; Maquet, J.; Chandrappa, G. T.; Livage, J. Vanadium Oxide Foams: An Insight into the Structure of the Vanadium Oxide Walls. Chem. Mater. 2005, 17, 6395−6402. (23) Xin, S.; Guo, Y.-G.; Wan, L.-J. Nanocarbon Networks for Advanced Rechargeable Lithium Batteries. Acc. Chem. Res. 2012, 45, 1759−1769. (24) Hou, B.-H.; Wu, X.-L.; Wang, Y.-Y.; Lü, H.-Y.; Liu, D.-H.; Sun, H.-Z.; Zhang, J.-P.; Guan, H.-Y. Full Protection for GrapheneIncorporated Micro-/Nanocomposites Containing Ultra-small Active Nanoparticles: the Best Li-Storage Properties. Part. Part. Syst. Charact. 2015, 32, 1020−1027. (25) Guo, J. Z.; Wu, X. L.; Wan, F.; Wang, J.; Zhang, X. H.; Wang, R. S. A Superior Na3V2(PO4)3-Based Nanocomposite Enhanced by Both N-Doped Coating Carbon and Graphene as the Cathode for SodiumIon Batteries. Chem. - Eur. J. 2015, 21, 17371−17378. (26) Liu, D.; Lu, H.; Wu, X.; Hou, B.; Wan, F.; Bao, S.; Yan, Q.; Xie, H.; Wang, R. Constructing the Optimal Conductive Network in MnObased Nanohybrids as High-rate and Long-life Anode Materials for Lithium-ion Batteries. J. Mater. Chem. A 2015, 3, 19738−19746. (27) Wan, F.; Guo, J.-Z.; Zhang, X.-H.; Zhang, J.-P.; Sun, H.-Z.; Yan, Q.; Han, D.-X.; Niu, L.; Wu, X.-L. In Situ Binding Sb Nanospheres on Graphene via Oxygen Bonds as Superior Anode for Ultrafast SodiumIon Batteries. ACS Appl. Mater. Interfaces 2016, 8, 7790−7799. (28) Xu, J. T.; Lin, Y.; Connell, J. W.; Dai, L. M. Nitrogen-Doped Holey Graphene as an Anode for Lithium-Ion Batteries with High Volumetric Energy Density and Long Cycle Life. Small 2015, 11, 6179−6185. (29) Xu, J. T.; Wang, M.; Wickramaratne, N. P.; Jaroniec, M.; Dou, S. X.; Dai, L. M. High-Performance Sodium Ion Batteries Based on a 3D Anode from Nitrogen-Doped Graphene Foams. Adv. Mater. 2015, 27, 2042−2048. (30) Yang, S.; Gong, Y.; Liu, Z.; Zhan, L.; Hashim, D. P.; Ma, L.; Vajtai, R.; Ajayan, P. M. Bottom-up Approach toward SingleCrystalline VO2-Graphene Ribbons as Cathodes for Ultrafast Lithium Storage. Nano Lett. 2013, 13, 1596−1601. (31) Yu, H.; Rui, X. H.; Tan, H. T.; Chen, J.; Huang, X.; Xu, C.; Liu, W. L.; Yu, D. Y. W.; Hng, H. H.; Hoster, H. E.; Yan, Q. Y. Cu Doped V2O5 Flowers as Cathode Material for High-Performance Lithium Ion Batteries. Nanoscale 2013, 5, 4937−4943. (32) Sun, Y.; Hu, X.; Luo, W.; Xia, F.; Huang, Y. Reconstruction of Conformal Nanoscale MnO on Graphene as a High-Capacity and Long-Life Anode Material for Lithium Ion Batteries. Adv. Funct. Mater. 2013, 23, 2436−2444. (33) Hu, Y. S.; Liu, X.; Muller, J. O.; Schlogl, R.; Maier, J.; Su, D. S. Synthesis and Electrode Performance of Nanostructured V2O5 by Using a Carbon Tube-in-Tube as a Nanoreactor and An Efficient Mixed-Conducting Network. Angew. Chem., Int. Ed. 2009, 48, 210− 214. (34) Pan, A.; Wu, H. B.; Yu, L.; Lou, X. W. Template-Free Synthesis of VO2 Hollow Microspheres with Various Interiors and Their Conversion into V2O5 for Lithium-Ion Batteries. Angew. Chem. 2013, 125, 2282−2286. (35) Shi, Y. F.; Guo, B. K.; Corr, S. A.; Shi, Q. H.; Hu, Y. S.; Heier, K. R.; Chen, L. Q.; Seshadri, R.; Stucky, G. D. Ordered Mesoporous Metallic MoO2 Materials with Highly Reversible Lithium Storage Capacity. Nano Lett. 2009, 9, 4215−4220. (36) Xia, Y.; Xiao, Z.; Dou, X.; Huang, H.; Lu, X.; Yan, R.; Gan, Y.; Zhu, W.; Tu, J.; Zhang, W.; Tao, X. Green and Facile Fabrication of Hollow Porous MnO/C Microspheres from Microalgaes for LithiumIon Batteries. ACS Nano 2013, 7, 7083−7092.

REFERENCES

(1) Poizot, P.; Laruelle, S.; Grugeon, S.; Dupont, L.; Tarascon, J.-M. Nano-Sized Transition-Metal Oxides as Negative-Electrode Materials for Lithium-Ion Batteries. Nature 2000, 407, 496−499. (2) Augustyn, V.; Simon, P.; Dunn, B. Pseudocapacitive Oxide Materials for High-Rate Electrochemical Energy Storage. Energy Environ. Sci. 2014, 7, 1597−1614. (3) Guo, C. X.; Wang, M.; Chen, T.; Lou, X. W.; Li, C. M. A Hierarchically Nanostructured Composite of MnO2/Conjugated Polymer/Graphene for High-Performance Lithium Ion Batteries. Adv. Energy Mater. 2011, 1, 736−741. (4) Zhang, H. J.; Wang, K. X.; Wu, X. Y.; Jiang, Y. M.; Zhai, Y. B.; Wang, C.; Wei, X.; Chen, J. S. MoO2/Mo2C Heteronanotubes Function as High-Performance Li-Ion Battery Electrode. Adv. Funct. Mater. 2014, 24, 3399−3404. (5) Zhang, W. M.; Wu, X. L.; Hu, J. S.; Guo, Y. G.; Wan, L. J. Carbon Coated Fe3O4 Nanospindles as a Superior Anode Material for Lithium-Ion Batteries. Adv. Funct. Mater. 2008, 18, 3941−3946. (6) He, X.; Antonelli, D. Recent Advances in Synthesis and Applications of Transition Metal Containing Mesoporous Molecular Sieves. Angew. Chem., Int. Ed. 2002, 41, 214−229. (7) Lang, X. Y.; Hirata, A.; Fujita, T.; Chen, M. W. Nanoporous Metal/Oxide Hybrid Electrodes for Electrochemical Supercapacitors. Nat. Nanotechnol. 2011, 6, 232−236. (8) Nethravathi, C.; Rajamathi, C. R.; Rajamathi, M.; Gautam, U. K.; Wang, X.; Golberg, D.; Bando, Y. N-Doped Graphene-VO2(B) Nanosheet-Built 3D Flower Hybrid for Lithium Ion Battery. ACS Appl. Mater. Interfaces 2013, 5, 2708−2714. (9) Chandrappa, G. T.; Steunou, N.; Livage, J. Materials Chemistry: Macroporous Crystalline Vanadium Oxide Foam. Nature 2002, 416, 702. (10) Lou, X. W.; Archer, L. A.; Yang, Z. Hollow Micro-/ Nanostructures: Synthesis and Applications. Adv. Mater. 2008, 20, 3987−4019. (11) Sun, Y. M.; Hu, X. L.; Yu, J. C.; Li, Q.; Luo, W.; Yuan, L. X.; Zhang, W. X.; Huang, Y. H. Morphosynthesis of a Hierarchical MoO2 Nanoarchitecture as a Binder-Free Anode for Lithium-Ion Batteries. Energy Environ. Sci. 2011, 4, 2870−2877. (12) Liu, H. M.; Wang, Y. G.; Wang, K. X.; Hosono, E.; Zhou, H. S. Design and Synthesis of a Novel Nanothorn VO2(B) Hollow Microsphere and Their Application in Lithium-Ion Batteries. J. Mater. Chem. 2009, 19, 2835−2840. (13) Zhang, C.; Chen, Z.; Guo, Z.; Lou, X. W. Additive-Free Synthesis of 3D Porous V2O5 Hierarchical Microspheres with Enhanced Lithium Storage Properties. Energy Environ. Sci. 2013, 6, 974−978. (14) Wang, Z. Y.; Zhou, L.; Lou, X. W. Metal Oxide Hollow Nanostructures for Lithium-Ion Batteries. Adv. Mater. 2012, 24, 1903− 1911. (15) Zhu, C.; Saito, G.; Akiyama, T. A New CaCO3-Template Method to Synthesize Nanoporous Manganese Oxide Hollow Structures and Their Transformation to High-Performance LiMn2O4 Cathodes for Lithium-Ion Batteries. J. Mater. Chem. A 2013, 1, 7077− 7082. (16) Jiao, F.; Bruce, P. G. Two- and Three-Dimensional Mesoporous Iron Oxides with Microporous Walls. Angew. Chem. 2004, 116, 6084− 6087. (17) Jiao, F.; Bruce, P. G. Mesoporous Crystalline β-MnO2a Reversible Positive Electrode for Rechargeable Lithium Batteries. Adv. Mater. 2007, 19, 657−660. (18) Chandrappa, G. T.; Vijayakumar, G.; Livage, J. Insertion Study of Alkali Metal Cations into Layered Vanadium Oxide Foam. J. Sol-Gel Sci. Technol. 2015, 73, 215−219. (19) Wang, X. B.; Zhang, Y. J.; Zhi, C. Y.; Wang, X.; Tang, D. M.; Xu, Y. B.; Weng, Q. H.; Jiang, X. F.; Mitome, M.; Golberg, D.; Bando, Y. Three-Dimensional Strutted Graphene Grown by Substrate-Free Sugar Blowing for High-Power-Density Supercapacitors. Nat. Commun. 2013, 4, 2905. F

DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces (37) Liu, Y. M.; Zhao, X. Y.; Li, F.; Xia, D. G. Facile Synthesis of MnO/C Anode Materials for Lithium-Ion Batteries. Electrochim. Acta 2011, 56, 6448−6452. (38) Lei, C.; Han, F.; Li, D.; Li, W. C.; Sun, Q.; Zhang, X. Q.; Lu, A. H. Dopamine as the Coating Agent and Carbon Precursor for the Fabrication of N-Doped Carbon Coated Fe3O4 Composites as Superior Lithium Ion Anodes. Nanoscale 2013, 5, 1168−1175.

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DOI: 10.1021/acsami.6b04587 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX