Hierarchical Mesoporous Iron Fluoride with Superior Rate

Subscriber access provided by UNIV NEW ORLEANS

Article

Hierarchical mesoporous Iron Fluoride with Superior Rate Performance for Lithium Ion Batteries Yangmei Han, Huiyu Li, Jinfeng Li, Huinan Si, Wentao Zhu, and Xinping Qiu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b11889 • Publication Date (Web): 31 Oct 2016 Downloaded from http://pubs.acs.org on November 1, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Hierarchical Mesoporous Iron Fluoride with Superior Rate Performance for Lithium Ion Batteries Yangmei Han, Huiyu Li, Jinfeng Li, Huinan Si, Wentao Zhu, and Xinping Qiu* Key Laboratory of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China. KEYWORDS: Iron fluoride, Hierarchical mesoporous, Lithium ion battery, Monodispersed, Cathode

ABSTRACT: Monodispersed mesoporous iron fluorides were synthesized by a low-cost reversed micelles method. The as-prepared materials with hierarchical mesoporous structure exhibit excellent rate capability (115.6 mAh g-1 at 2000 mA g-1), which is superior to many other carbon-free iron fluoride. In addition, a high reversible capacity of 143.2 mAh g-1 can be retained after 100 cycles at 1000 mA g-1. The outstanding electrochemical features can be attributed to the particular hierarchical mesoporous structure facilitating electrolyte penetration as well as rapid electronic and ionic transportation.

1. Introduction Over the past few decades, rechargeable lithium-ion batteries (LIBs) have been widely used in various portable electronics devices, and are further expanded to electric vehicles and smart electric grid.1-3 However, the specific capacity of commercially available cathode materials for

ACS Paragon Plus Environment

1


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 19

LIBs are still unable to meet the increasing demand. Therefore, alternative cathode materials with higher energy and power densities are in urgent need.4-6 Among the various candidates, iron fluorides have drawn tremendous attention because of high operation voltage, huge theoretical capacity (712 mAh g-1, 3e- transfer), plentiful sources and better safety.7-9 Despite these advantages, their practical application for LIBs has been retarded by the poor rate capability, due to the sluggish electronic transport. In order to solve this issue, some researchers tried to introduce conductive materials with iron fluoride, such as carbon nanotubes(CNTs)10, graphite oxide11,

12

, graphene13-15, mesoporous carbon16-18, and carbon nanohorns19 to enhance the

electronic conductivity.20 Although the specific high-rate capacity of FeF3 is increased, introduction of inactive agents will inevitably decrease the overall capacity and the tap density of the cathode material. Another generally accepted approach is to prepare nanoscaled active materials.21 It is wellknown that smaller size ensures a shorter diffusion path of Li+ and electron, which is beneficial to capacity and rate performance.22-24 Iron based fluoride with various nanostructures have been successfully synthesized, such as nanospheres25, 26, nanowires27, 28, and hollow microspheres29, 30. Although their performance were improved to some extent, there are still distance from expectation. Recently, iron fluorides with hierarchical structures have drew attention according to their promising applications advantages for LIBs.24,

29, 31

Compared with nanospheres and

nanowires, hierarchical nanostructures are mainly assembled from several particles with nanosize, which accounts for large specific surface area and void.21 Therefore, this hierarchical nanostructure provides enough space for electrolyte access and alleviate the volume effect. To date, some iron-based fluorides with hierarchical nanostructures have been reported.29,

32

Unfortunately, solvothermal method with high energy consumption are usually involved in the


2

Page 3 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


synthesis process, which prevents them from large scale production. In addition, it is difficult to obtain a pure single phase of FeF3•0.33H2O because of uncontrollable side reactions. Obviously, it is desirable yet challenging to develop a facile strategy to synthesize hierarchical nanostructured iron fluorides with homogeneous morphology. Herein, we report the design and preparation of phase-pure hierarchical mesoporous FeF3• 0.33H2O by a reversed micelles method. Iron (III) acetylacetonate ( Fe(acac)3) is chosen as iron source, which is its first use in the synthesis of iron fluorides. Meanwhile, morphologies and diameters of nanostructures were readily tuned by controlling the temperature of synthetic process. The hierarchical mesoporous FeF3 •0.33H2O obtained at 90 ⁰C is tested as cathode materials for LIBs, which exhibits an outstanding rate capability of 115.6 mAh g-1 at a high rate over 10C (i.e. current density of 2000 mA g-1), and an impressive discharge capacity of 143.2 mAh g-1 at 1000 mA g-1 after 100 cycles. 2. Experimental Section 2.1 Synthesis of the hierarchical mesoporous structured FeF3 • 0.33H2O. In this study, hierarchical mesoprous structured FeF3•0.33H2O materials were prepared via a facile reverse micelles method. By control the temperature of synthetic process, we obtained series samples named FX, where X stands for the temperature. In detail, take F90 for example, 5 mmol Iron (III) acetylacetonate ( Fe(acac)3 ) was dropped into 100 mL tetraethylene glycol (TEG) at 90 ⁰C with stirring for 1 hour. Afterwards, 3 mL hydrofluoric acid (aqueous HF solution, 40 wt%) was slowly dripped into the above solution and then the mixture was maintained in the same condition (90 ⁰C with stirring) for 16 hours. After that, the suspension was filtered by centrufuging at 10000 rpm for 45 min and washed with ethanol. After drying overnight at 80 ⁰C, the collected powders were further calcined at 220 ⁰C in vacuum for 12 h to remove moisture


3


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 19

and organic residues on the surface of particles. The other samples were prepared with a similar synthesis process at different reaction temperatures. 2.2 Materials characterization. Morphology of all samples were observed via Transmission Electron Microscopy (Hitachi, H-7650, 80 keV) and Scanning Electron Microscopy (Zeiss, Merlin, 5 keV). High resolution-TEM (HRTEM, JEOL, JEM-2100, 200 keV) was further used to evaluate the microstructure and collect selective area diffraction pattern (SEAD). The crystal structure of as-prepared samples were checked by X-ray diffractometer (Bruker D8 Advance) using Cu Kα radiation in the range between 10° and 80° (2θ values). N2 sorption measurements were performed on a High Speed Gas Sorption at 77.3 K (Quantachrome NOVA 1000e). 2.3 Electrochemical characterization. All electrodes were prepared by casting slurries on current collector (Al foil, 20 µm), containing active materials (80 wt%), carbon black (10 wt%), and polyvinylidene fluoride (PVDF, 10 wt%). Then the electrodes were dried in a vacuum oven at 120 ⁰C for 12h. The thickness of prepared electrodes was about 150 µm and the average mass loading is about 1.3 mg/cm2. Lithium foil was used as counter electrode, and the electrolyte was composed of 1 M LiPF6 in ethylene carbonate -ethyl methyl carbonate -dimethyl carbonate (ECEMC-DMC, 1:1:1 in volume). Galvanostatic measurements were conducted with a NEWAREBTS battery test system between 1.8 and 4.5 V vs Li/Li+. Three electrode cells (ECC-REF model, EL-CELL) were assembled for electrochemical impedance spectra (EIS) tests, using Li foil as reference and conter electrodes. EIS measurements were conducted with PARSTAT2273 electrochemical workstation (AMETEK) in the frequency range from 100 kHz and 0.1 kHz. All above-mentioned cells were assembled in an Ar-filled glove box. 3. Results and discussion


4

Page 5 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


A possible synthesis mechanism for hierarchical mesoporous FeF3 •0.33H2O is illustrated in Figure 1, and the experimental details are provided in the Supporting Information. In this reaction system, Iron (III) acetylacetonate and hydrogen fluoride solution were used as iron precursor and fluorine source, respectively. Firstly, Fe(acac)3 was dissolved in tetraethylene glycol, which has two parts: hydrophobic acetylacetonate groups and hydrophilic Fe3+ cation. After hydrogen fluoride solution was added to the reaction, reverse micelles will be formed through self-assembly of Fe(acac)3 in the tetraethylene glycol. As soft templates, these micelles promote the formation of nanostructured FeF3 • 0.33H2O. The morphology and size of the micelles can be tailored by the temperature, therefore, a series of FeF3•0.33H2O samples with different morphology will be obtained.33, 34 In order to understand the formation process, iron fluoride resultants during the reaction were monitored by TEM (Figure S1). Interestingly, we found that the nanostructure formed quickly and had no significant change as the reaction proceeding. Detailed mechanism of the morphology evolution will be demonstrated in the future. X-ray diffraction (XRD) patterns were collected to examine the crystallographic structures of FeF3•0.33H2O prepared under different temperatures. The samples named F50, F60, F70, F80, F90 and F100 represent the products obtained at 50 ⁰C, 60 ⁰C, 70 ⁰C, 80 ⁰C, 90 ⁰C and 100 ⁰C, respectively. In Figure S2, all samples were indexed to the standard hexagonal-tungsten-bronze type (HTB) FeF3•0.33H2O (JCPDS card No. 76-1262, a=7.423 , b= 12.73 , c= 7.526 Å), without any impurity signal.35 The diffraction peaks of F100 are broad and weak compared with other samples, which can be ascribed to its smaller particle size and lower crystallinity. Morphologies of FeF3 • 0.33H2O samples prepared at different temperatures are shown in Figure 2. Figure 2a indicates that F50 is composed of homogeneous and monodisperse nanospheres, with a size of about 250 nm. As the synthetic temperature increased, F60, F70 and


5


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 19

F80 exhibit similar spherical shape to that of F50, but the diameter is significantly larger (500~600 nm). However, when the reaction temperature further rised to 90 ⁰C (Figure 2e), F90 has a remarkable decrease in particle size (~200 nm), and all particles present a flower-like shape. Finally, when the reaction temperature reaches 100 ⁰C (Figure 2f), F100 displays a similar nanostructure with F90, with the particle size decreased from 200 nm to ~100 nm. As far as we know, this is the first reveal of such small size of iron fluorides with hierarchical mesoporous structure. Microstructure details of F50, F90 and F100 were further characterized by transmission electron microscope (TEM) and high-resolution TEM (HRTEM), as shown in Figure 3. Figure 3a reveals that the F50 nanospheres appear well-dispersed, uniformly sized and regularly shaped. The enlarged HRTEM image (Figure 3b) shows that the nanosphere is composed of small nanocrystals with interparticle mesopores distributed throughout the nanosphere, which was further confirmed by nitrogen adsorption and desorption test. As illustrated in Figure 3d and 3e, F90 displays a flower-like shape with hierarchical mesoporous structure. HRTEM image (Figure 3e) suggests that this hierarchical mesoporous structure of F90 is constructed with dozens of nanorods connecting to each other via the particle center. In Figure 3g and 3h, we can see that F100 is assembled by several nanorods with ~20 nm thickness. Furthermore, it is interesting to find sufficient voids between the adjacent nanorods in the particle, which is vital for the permeation of electrolyte. Through analysis of the HRTEM images (Figure 3c, 3f and 3i), a lattice fringe corresponding to d220 = 3.2 Å is observed. Moreover, the corresponding selected area electron diffraction (SAED) analysis (inset of Figure 3c, 3f and 3i) confirms the products belong to FeF3•0.33H2O.


6

Page 7 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


To further investe the hierarchical mesoporous structures and their pore size distribution, nitrogen adsorption and desorption measurements were conducted (Figure S3, Table S1). All FeF3•0.33H2O samples show a type Ⅳ isotherm, which stands for a mesoporous structure.36 The average pore size of F50 (inset of Figure S3a) is about 3.5 nm. Whereas F90 (inset of Figure S3b) and F100 (inset of Figure S3c) give different pore size distribution mainly in the range of 10-35 nm, which is considered from the stacking of nanorods. This unique hierarchical mesoporous structure is beneficial for electrolyte accessibility and rapid lithium-ion diffusion.37 Based on those results, we further investigated the electrochemical performance of the prepared FeF3•0.33H2O samples. Figure 4a shows the galvanostatic charge/discharge curves of the first two cycles for F90, between 1.8 and 4.5 V with a current density of 100 mA g-1. For comparison, the curves of F100 and F50 were also characterized (Figure S4a and b). The initial discharge capacity is 210, 255.3 and 220.8 mAh g-1 for F50 , F90 and F100, respectively. The high capacity is mainly ascribed to the reduced particle size and homogeneous morphologies. Besides, two plateaus presented at 2.7 V and 1.8 V, can be explained by an insertion reaction and a conversion reaction, respectively.29 In the second cycle, the discharge capacity of F50, F90 and F100 dropped to 162.54, 231.8, and 218 mAh g-1, respectively. The capacity fading in the first few cycles may be attribute to the occurred side reaction at the surface of particles. Unsatisfactory performance of F50 further hints the importance of the microstructure in active material. Rate capability of the three samples were also characterized. Figure 4b shows the specific discharge capacity of three samples during continuous cycling at various current densities from 100 to 2000 mA g-1 in the voltage range of 1.8-4.5 V. Obviously, F90 and F100 exhibited much better rate performance than F50, which can be attributed to their reduced particle size and


7


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 19

unique hierarchical mesoporous structures. F90 shows the best rate performance with discharge capacities of 211.3, 185.6, 168.8, 145.7 and 115.6 mAh g-1 with current density of 100, 200, 500, 1000 and 2000 mA g-1, respectively. The decrease in the discharge capacity at high current density is due to the slightly increased polarization.38 When the cycling current changes back to the 100 mA g-1 after 50 cycles, the delivered capacity is close to 178.1 mAh g-1, retaining approximately 84.3% of the initial capacity. The rate capability of as-prepared F90 is amongst the largest values ever reported for FeF3•0.33H2O without conducting agent coating (Table S2). Such excellent performance can be derived from the hierarchical mesoporous structure which can promote the transportation of electrolyte, and the nanoscopic dimension of flower-like nanostructures which offer shorter distance for electron and lithium ion diffusion. Figure 4c shows the cyclic stability of the three samples. Even at current density of 1000 mA g-1, the discharge specific capacity of F90 and F100 remain as high as 143.2 mAh g-1 and 133.5 mAh g-1 after 100 cycles, respectively. Coulombic efficiency also keeps constant at approximately 100% in subsequent cycles. In comparison, the discharge capacity of F50 drops to 84.2 mAh g-1 after 100 cycles at the same condition. To gain an insight into the improved electrochemical performance of F90, electrochemical impedance spectroscopy (EIS) and the TEM images of F90 and F100 after 50 cycles were investigated. As seen in Figure 4d, the Nyquist plots for three electrodes after 10 cycles consist of a semicircle in the high-frequency region and a tail in the low-frequency region. In previous reports39, the semicircle is generally associated with the charge-transfer process, and the impedance tail can be attributed to the bulk diffusional effects of Li+. Compared with F50, F90 and F100 present impressive decrease in charge-transfer resistance, which provide internal reason for their enhanced dynamics.40 Figure 5(a-c) show Nyquist plots of three samples at two different states (after 10 cycles and 50 cycles).


8

Page 9 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The data were analyzed by fitting to an equivalent circuit shown in Figure 5d, and the value of Rct are listed in Table S3. After 50 cycles, the Rct of F100 increases from 35.1 Ω to 53 Ω, whereas the charge-transfer resistance of F90 does not change obviously. Moreover, we found that the nanostructure of F90 maintains intact even after 50 cycles (inset of Figure 5b). By contrast, the nanostruture of F100 is damaged during the cyclic process (inset of Figure 5c). Therefore, F90 exhibited better electrochemical performance than F100, even though F100 have larger specific area and smaller size. 4. Conclusion In conclusion, a low-cost method has been developed to prepare monodisperse nanostructured iron fluorides with the size ranging from 100 nm to 500 nm. Morphology of the iron fluorides depends on the temperature in the synthesis process. When the temperature increased to 90 ⁰C, transformation of nanospheres to hierarchical mesoporous structure has been demonstrated. Sample F90 with hierarchical mesoporous structure exhibited a large initial discharging capacity (255.3 mAh g-1 at 100 mA g-1), superior rate capability (115.6 mAh g-1 at 2000 mA g-1) as well as stable cyclability (a residual capacity of 143.2 mAh g-1 after 100 cycles at 1000 mA g-1). The outstanding electrochemical features are mainly attributed to its particular hierarchical mesoporous structure, which is beneficial to rapid transmission of electrons and lithium ions. Considering the fact that all reactants are inexpensive and synthesis process is efficient, this hierarchical mesoporous iron fluoride is a promising cathode candidate for the next generation of lithium batteries.

ASSOCIATED CONTENT


9


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 19

Supporting Information: XRD data of all samples, TEM images of the products obtained at different reaction time, N2 adsorption/desorption isotherms of all samples, and discharge-charge curves of F100 and F50. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author *Xinping Qiu, Email: [email protected] ACKNOWLEDGMENT The work was supported by National Key Project on Basic Research (2015CB251104), ChinaUS Electric Vehicle Project (S2016G9004), Natural Science Foundation of China (51361130151, 21273129) and Beijing Natural Science Foundation (2120001).

REFERENCES (1) (2) (3) (4) (5)

(6)

(7)

Armand, M.; Tarascon, J. M., Building Better Batteries. Nature 2008, 451, 652-657. Tarascon, J. M.; Armand, M., Issues and Challenges Facing Rechargeable Lithium Batteries. Nature 2001, 414, 359-367. Goodenough, J. B.; Kim, Y., Challenges for Rechargeable Li Batteries. Chem. Mater. 2010, 22, 587-603. Larcher, D.; Tarascon, J. M., Towards Greener and More Sustainable Batteries for Electrical Energy Storage. Nature Chem. 2015, 7, 19-29. Cao, R. G.; Chen, J. Z.; Han, K. S.; Xu, W.; Mei, D. H.; Bhattacharya, P.; Engelhard, M. H.; Mueller, K. T.; Liu, J.; Zhang, J. G., Effect of the Anion Activity on the Stability of Li Metal Anodes in Lithium-Sulfur Batteries. Adv. Funct. Mater. 2016, 26, 3059-3066. Wang, D. P.; Belharouak, I.; Zhou, G. W.; Amine, K., Nanoarchitecture Multi-Structural Cathode Materials for High Capacity Lithium Batteries. Adv. Funct. Mater. 2013, 23, 1070-1075. Ahmad, M.; Shi, Y. Y.; Nisar, A.; Sun, H. Y.; Shen, W. C.; Wei, M.; Zhu, J., Synthesis of Hierarchical Flower-Like ZnO Nanostructures and Their Functionalization by Au Nanoparticles for Improved Photocatalytic and High Performance Li-ion Battery Anodes. J. Mater. Chem. 2011, 21, 7723-7729.


10

Page 11 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(8)

(9) (10)

(11)

(12)

(13)

(14)

(15)

(16) (17)

(18)

(19)

(20) (21) (22) (23)

Han, Y. L.; Hu, J. L.; Yin, C. L.; Zhang, Y.; Xie, J. J.; Yin, D. G.; Li, C. L., Iron-based Fluorides of Tetragonal Tungsten Bronze Structure as Potential Cathodes for Na-ion Batteries. J. Mater. Chem. A 2016, 4, 7382-7389. Badway, F.; Pereira, N.; Cosandey, F.; Amatucci, G. G., Carbon-Metal Fluoride Nanocomposites. J. Electrochem. Soc. 2003, 150, A1209-A1218. Kim, S. W.; Seo, D. H.; Gwon, H.; Kim, J.; Kang, K., Fabrication of FeF3 Nanoflowers on CNT Branches and Their Application to High Power Lithium Rechargeable Batteries. Adv. Mater. 2010, 22, 5260-5264. Jiang, M. L.; Wang, X. Y.; Wei, S. Y.; Shen, Y. Q.; Hu, H., An Ionic-Liquid-Assisted Approach to Synthesize a Reduced Graphene Oxide Loading Iron-Based Fluoride as a Cathode Material for Sodium-Ion Batteries. J. Alloys Compd. 2016, 670, 362-368. Ali, G.; Oh, S. H.; Kim, S. Y.; Kim, J. Y.; Cho, B. W.; Chung, K. Y., An OpenFramework Iron Fluoride and Reduced Graphene Oxide Nanocomposite as a HighCapacity Cathode Material for Na-Ion Batteries. J. Mater. Chem. A 2015, 3, 1025810266. Zhao, X.; Hayner, C. M.; Kung, M. C.; Kung, H. H., Photothermal-Assisted Fabrication of Iron Fluoride-Graphene Composite Paper Cathodes for High-Energy Lithium-Ion Batteries. Chem. Commun. 2012, 48, 9909-9911. Liu, J.; Wan, Y.; Liu, W.; Ma, Z.; Ji, S.; Wang, J.; Zhou, Y.; Hodgson, P.; Li, Y., Mild and Cost-Effective Synthesis of Iron Fluoride–Graphene Nanocomposites for High-Rate Li-ion Battery Cathodes. J. Mater. Chem. A 2013, 1, 1969-1975. Hu, X. B.; Ma, M. H.; Mendes, R. G.; Zeng, M. Q.; Zhang, Q.; Xue, Y. H.; Zhang, T.; Rummeli, M. H.; Fu, L., Li-Storage Performance of Binder-Free and Flexible Iron Fluoride@Graphene Cathodes. J. Mater. Chem. A 2015, 3, 23930-23935. Li, B.; Zhang, N.; Sun, K., Confined Iron Fluoride@CMK-3 Nanocomposite as An Ultrahigh Rate Capability Cathode for Li-ion Batteries. Small 2014, 10, 2039-2046. Jung, H.; Shin, J.; Chae, C.; Lee, J. K.; Kim, J., FeF3/Ordered Mesoporous Carbon (OMC) Nanocomposites for Lithium Ion Batteries with Enhanced Electrochemical Performance. J. Phys. Chem. C 2013, 117, 14939-14946. Ma, R.; Wang, M.; Tao, P.; Wang, Y.; Cao, C.; Shan, G.; Yang, S.; Xi, L.; Chung, J. C. Y.; Lu, Z., Fabrication of FeF3 Nanocrystals Dispersed Into a Porous Carbon Matrix as a High Performance Cathode Material for Lithium Ion Batteries. J. Mater. Chem. A 2013, 1, 15060-15067. Fan, L.; Li, B.; Zhang, N.; Sun, K., Carbon Nanohorns Carried Iron Fluoride Nanocomposite With Ultrahigh Rate Lithium Ion Storage Properties. Sci. Rep. 2015, 5, 19. Badway, F.; Cosandey, F.; Pereira, N.; Amatucci, G. G., Carbon Metal Fluoride Nanocomposites. J. Electrochem. Soc. 2003, 150, A1318-A1327. Yu, Z. N.; Tetard, L.; Zhai, L.; Thomas, J., Supercapacitor Electrode Materials: Nanostructures From 0 to 3 Dimensions. Energy Environ. Sci. 2015, 8, 702-730. Wu, H.; Cui, Y., Designing Nanostructured Si Anodes for High Energy Lithium Ion Batteries. Nano Today 2012, 7, 414-429. Zhang, L.; Wu, H. B.; Lou, X. W., Iron-Oxide- Based Advanced Anode Materials for LithiumIon Batteries. Adv. Energy Mater. 2014, 4, 1-11.


11


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(24)

(25)

(26)

(27)

(28)

(29)

(30)

(31)

(32)

(33) (34)

(35)

(36)

(37)

(38)

Page 12 of 19

Trogadas, P.; Ramani, V.; Strasser, P.; Fuller, T. F.; Coppens, M. O., Hierarchically Structured Nanomaterials for Electrochemical Energy Conversion. Angew. Chem. Int. Ed. 2016, 55, 122-148. Chu, Q.; Xing, Z.; Tian, J.; Ren, X.; Asiri, A. M.; Al-Youbi, A. O.; Alamry, K. A.; Sun, X., Facile Preparation of Porous FeF3 Nanospheres as Cathode Materials for Rechargeable Lithium-Ion Batteries. J. Power Sources 2013, 236, 188-191. Long, Z.; Hu, W.; Liu, L.; Qiu, G.; Qiao, W.; Guan, X.; Qiu, X., Mesoporous Iron Trifluoride Microspheres as Cathode Materials for Li-ion Batteries. Electrochim. Acta 2015, 151, 355-362. Li, L.; Meng, F.; Jin, S., High-Capacity Lithium-Ion Battery Conversion Cathodes Based on Iron Fluoride Nanowires and Insights Into the Conversion mechanism. Nano lett. 2012, 12, 6030-6037. Li, L. S.; Yu, Y. H.; Meng, F.; Tan, Y. Z.; Hamers, R. J.; Jin, S., Facile Solution Synthesis of Alpha-FeF3 Center Dot 3H(2)O Nanowires and Their Conversion to AlphaFe2O3 Nanowires for Photoelectrochemical Application. Nano Lett. 2012, 12, 724-731. Lu, Y.; Wen, Z.; Jin, J.; Rui, K.; Wu, X., Hierarchical Mesoporous Iron-Based Fluoride with Partially Hollow Structure: Facile Preparation and High Performance as Cathode Material for Rechargeable Lithium Ion Batteries. Phys. Chem. Chem. Phys. 2014, 16, 8556-8562. Liu, J.; Liu, W.; Ji, S.; Wan, Y.; Gu, M.; Yin, H.; Zhou, Y., Iron Fluoride Hollow Porous Microspheres: Facile Solution-Phase Synthesis and Their Application for Li-ion Battery Cathodes. Chem. Eur. J 2014, 20, 5815-5820. Chen, Y. M.; Yu, L.; Lou, X. W., Hierarchical Tubular Structures Composed of Co3O4 Hollow Nanoparticles and Carbon Nanotubes for Lithium Storage. Angew. Chem. Int. Ed. 2016, 55, 5990-5993. Li, B.; Cheng, Z.; Zhang, N.; Sun, K., Self-supported, Binder-free 3D Hierarchical Iron Fluoride Flower-like Array As High Power Cathode Material for Lithium Batteries. Nano Energy 2014, 4, 7-13. Burda, C.; Chen, X. B.; Narayanan, R.; El-Sayed, M. A., Chemistry and Properties of Nanocrystals of Different Shapes. Chem. Rev. 2005, 105, 1025-1102. Diodati, S.; Dolcet, P.; Casarin, M.; Gross, S., Pursuing the Crystallization of Mono- and Polymetallic Nanosized Crystalline Inorganic Compounds by Low-Temperature WetChemistry and Colloidal Routes. Chem. Rev. 2015, 115, 11449-11502. Li, C.; Gu, L.; Tsukimoto, S.; van Aken, P. A.; Maier, J., Low-Temperature Ionic-LiquidBased Synthesis of Nanostructured Iron-Based Fluoride Cathodes for Lithium Batteries. Adv. Mater. 2010, 22, 3650-3654. Li, L. L.; Tian, T.; Jiang, J.; Ai, L. H., Hierarchically Porous CO3O4 Architectures with Honeycomb-Like Structures for Efficient Oxygen Generation from Electrochemical Water Splitting. J. Power Sources 2015, 294, 103-111. Zhao, D.; Cao, M., Constructing Highly Graphitized Carbon-Wrapped Li3VO4 Nanoparticles with Hierarchically Porous Structure as a Long Life and High Capacity Anode for Lithium-Ion Batteries. ACS Appl. Mater. Interfaces 2015, 7, 25084-25093. Pan, J.; Zhong, L.; Li, M.; Luo, Y. Y.; Li, G. H., Microwave-Assisted Solvothermal Synthesis of VO2 Hollow Spheres and Their Conversion into V2O5 Hollow Spheres with Improved Lithium Storage Capability. Chem. Eur. J 2016, 22, 1461-1466.


12

Page 13 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(39)

(40)

Lv, Q. L.; Liu, Y.; Ma, T. Y.; Zhu, W. T.; Qiu, X. P., Hollow Structured Silicon Anodes with Stabilized Solid Electrolyte Interphase Film for Lithium-Ion Batteries. ACS Appl. Mater. Interfaces 2015, 7, 23501-23506. Yan, B.; Li, X. F.; Bai, Z. M.; Zhao, Y.; Dong, L.; Song, X. S.; Li, D. J.; Langford, C.; Sun, X. L., Crumpled Reduced Graphene Oxide Conformally Encapsulated Hollow V2O5 Nano/Microsphere Achieving Brilliant Lithium Storage Performance. Nano Energy 2016, 24, 32-44.

Figure captions Figure 1. Schematic illustration of the preparation of FeF3•0.33H2O samples (F50 and F90) Figure 2. SEM images of FeF3•0.33H2O samples obtained at different temperature: (a) 50⁰C, (b) 60 ⁰C, (c) 70 ⁰C, (d) 80 ⁰C, (e) 90 ⁰C, (f) 100 ⁰C. Scale bars: 200nm. Figure 3. TEM characterizations of the as-prepared FeF3•0.33H2O samples: (a) F50, (d) F90, and (g) F100; HRTEM images of single nanoparticle of FeF3•0.33H2O samples: (b) F50, (e) F90 and (h) F100; HRTEM image of the lattice planes of FeF3•0.33H2O samples: (c) F50, (f) F90 and (i) F100, inset is the corresponding SAED pattern that indicates polycrystalline character Figure 4. Electrochemical characterization of FeF3•0.33H2O samples (F50, F90 and F100) (a) discharge-charge curves of F90 at a current density of 100 mA g-1 in the voltage window 1.84.5V; (b) discharge capacity versus cycle number at different current densities of FeF3•0.33H2O samples; (c) cyclic performance of FeF3•0.33H2O samples at a current density of 1 A g-1; (d) Nyquist plots of FeF3•0.33H2O samples after 10 cycles at a current density of 100 mA g-1 Figure 5. Nyquist plots of (a) F50, (b) F90 and (c) F100 from 100 kHz to 0.1 kHz, insets are the TEM images of corresponding electrodes after 50 cycles, which shows the morphology of F50 and F90 remains intact; (d) the equivalent electrical circuit model.


13


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 19

FIGURES

Figure 1. Schematic illustration of the preparation of FeF3•0.33H2O samples (F50 and F90)


14

Page 15 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. SEM images of FeF3•0.33H2O samples obtained at different temperature: (a) 50 ⁰C, (b) 60 ⁰C, (c) 70 ⁰C, (d) 80 ⁰C, (e) 90 ⁰C, (f) 100 ⁰C. Scale bars: 200nm.


15


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 19

Figure 3. TEM characterizations of the as-prepared FeF3•0.33H2O samples: (a) F50, (d) F90, and (g) F100; HRTEM images of single nanoparticle of FeF3•0.33H2O samples: (b) F50, (e) F90 and (h) F100; HRTEM image of the lattice planes of FeF3•0.33H2O samples: (c) F50, (f) F90 and (i) F100, inset is the corresponding SAED pattern that indicates polycrystalline character


16

Page 17 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. Electrochemical characterization of FeF3•0.33H2O samples (F50, F90 and F100) (a) discharge-charge curves of F90 at a current density of 100 mA g-1 in the voltage window 1.84.5V; (b) discharge capacity versus cycle number at different current densities of FeF3•0.33H2O samples; (c) cyclic performance of FeF3•0.33H2O samples at a current density of 1 A g-1; (d) Nyquist plots of FeF3•0.33H2O samples after 10 cycles at a current density of 100 mA g-1


17


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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 19

Figure 5. Nyquist plots of (a) F50, (b) F90 and (c) F100 from 100 kHz to 0.1 kHz, insets are the TEM images of corresponding electrodes after 50 cycles, which shows the morphology of F50 and F90 remains intact; (d) the equivalent electrical circuit model.


18

Page 19 of 19

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 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table of Contents


19

Hierarchical Mesoporous Iron Fluoride with Superior Rate

Recommend Documents