Research Article pubs.acs.org/journal/ascecg
Synthesis, Crystal Structure, and Electrochemical Properties of Alluaudite Na1.702Fe3(PO4)3 as a Sodium-Ion Battery Cathode Dan Liu† and G. Tayhas R. Palmore*,‡,† †
Department of Chemistry and ‡Materials Science Group, School of Engineering, Brown University, Providence, Rhode Island 02912, United States S Supporting Information *
ABSTRACT: Sodium-ion batteries hold promise as an enabling technology for large-scale energy storage that is safer, less expensive, and lower environmentally impactful than their equivalent lithium-ion batteries. Reported herein is the one-pot hydrothermal synthesis, crystal structure, and electrochemical properties of a promising sodium-ion battery cathode material, an alluaudite phase of Na1.702Fe3(PO4)3. After ball milling and carbon coating, this material exhibits a reversible capacity of ∼140 mAh/g with good cycling performance (93% of the initial capacity is retained after 50 cycles) and excellent rate capability. This alluaudite compound and its method of preparation is a promising cathode for large-scale battery applications that are earth-abundant and sustainable. KEYWORDS: Alluaudite, Cathode, Sodium-ion batteries, Electrochemical study Li0.78Na0.22MnPO4.21 When used as cathode materials in Liion batteries, both Li0.47Na0.2FePO4 (140 mAh/g) and Li0.78Na0.22MnPO4 (135 mAh/g) exhibit relatively high capacity and good cycling performance. However, when used as cathode materials in Na-ion batteries, these materials exhibit poor electrochemical properties including low capacity and significant polarization under load.17−19 Thus, improving the performance of alluaudite materials for use in Na-ion batteries is highly desirable. Herein, we show that alluaudite Na1.702Fe3(PO4)3, synthesized via a modified hydrothermal method and subsequently ball-milled and carbon-coated, is an excellent cathode material for Na-ion batteries. This material exhibits high reversible capacity (∼140 mAh/g), high voltage, excellent rate capability, good cycling characteristics, and thermal stability, characteristics that are necessary for largescale batteries based on earth-abundant materials.
1. INTRODUCTION Concern about the overuse of fossil fuels has stimulated research on sustainable approaches to meet our energy demands. One promising solution is to make better use of renewable energy, such as solar, wind, and wave power. However, these sources of energy vary in time and space, thus requiring development of efficient and reliable energy storage systems.1 The lithium-ion battery dominates the portable electronic market because of its high energy density, flexible design, and long service life.2 However, the increasing costs and potential geopolitical constraints on lithium reserves make Liion batteries unsuitable for large-scale energy storage applications.3 As such, renewed interest in Na-ion batteries has occurred in recent years.4 Na-ion batteries should be less expensive than Li-ion batteries because the raw materials for a Na-ion batteries are more abundant than those of Li-ion batteries. Moreover, Na-ion compounds exist in a variety of novel intercalation structures that are not found as Li-ion compounds.5 These advantages make Na-ion batteries very promising for large-scale storage applications. Covalent polyanionic compounds based on earth-abundant metals have been studied in recent years in the search for new cathode materials for Na-ion batteries.6−16 Among these compounds, alluaudite phases with the chemical formula, NaxM3(PO4)3, where M sites are occupied by Fe, Mn, or Ni, have attracted new interest because of their channeled structures, high theoretical capacity (160 mAh/g), and good thermal stability. To date, several alluaudite compounds have been investigated for battery applications, including: LixNa2−xFeMn2(PO4)3,17 NaMnFe2(PO4)3,18 Li0.5Na0.5MnFe2(PO4)3 and Li 0 . 7 5 Na 0 . 2 5 MnFe 2 (PO 4 ) 3 , 1 9 Li 0 . 4 7 Na 0 . 2 FePO 4 , 2 0 and © 2017 American Chemical Society
2. EXPERIMENTAL SECTION 2.1. Synthesis. Na1.702Fe3(PO4)3 was prepared via hydrothermal synthesis. Starting materials were (NH4)2Fe(SO4)2·6H2O (Aldrich), H3PO4 (Fisher), and NaOH (Aldrich) and were used as received. Reactants were dissolved in water with a 1:1:3 molar ratio and subsequently transferred to a Parr autoclave, which was sealed and heated at 180 °C for 6 h. After cooling to room temperature, the reaction was filtered of precipitated product. The product was dried to yield a fine powder with a greenish gray color. An SPEX 8000D miller was used to ball-mill as-synthesized samples of Na1.702Fe3(PO4)3. Received: February 6, 2017 Revised: April 21, 2017 Published: June 1, 2017 5766
DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
Research Article
ACS Sustainable Chemistry & Engineering
Figure 1. (a) XRD pattern and Rietveld refinement of Na1.702Fe3(PO4)3 with χ2 = 1.92, Rwp = 9.24, and Rexp = 6.67. (b) Structure of alluaudite phase of Na1.702Fe3(PO4)3 where Fe2+ and Fe3+ ions are represented as aqua-colored octahedra and PO4− ions are represented as magenta-colored tetrahedra. Corner sites shared between the octahedra and tetrahedra correspond to oxygen atoms. Sodium ions occupy the two channels that run parallel to the c-axis. 2.2. Carbon Coating. A dried powder of Na1.702Fe3(PO4)3 was added to a small amount of ethanol that contained 80 wt % of citric acid (Aldrich). This mixture was sonicated to wet the powder completely with citric acid solution and subsequently heated at 600 °C under Ar for 5 h to deposit the carbon coating. A control sample was prepared by annealing the Na1.702Fe3(PO4)3 powder in the absence of citric acid at 600 °C under flowing Ar for 5 h. 2.3. Material Characterization. Scanning electron microscopy (SEM) using a field emission microscope (LEO 1530) operating at 10 kV was used to characterize the morphology of all samples. An FEI CM20 transmission electron microscope (TEM) operating at 200 kV was used for TEM studies. A Bruker D8-Discover diffractometer (operating at 40 mA, 40 kV) equipped with a Cu Kα radiation source was used to obtain powder X-ray diffractograms. 2.4. Electrochemical Tests. Active materials were mixed initially with 20 wt % Super P carbon black (Timcal) and a 10 wt % solution of polyvinylidene difluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) to form a slurry. After stirring at room temperature overnight, the slurry was skimmed onto aluminum foil using a doctor blade. Subsequently, samples were dried for 6 h at 110 °C under vacuum. Coin cell batteries were assembled in an inert atmosphere drybox ([H2O] < 0.1 ppm, ([O2] < 0.1 ppm) using thin discs of metallic sodium as the anode, a glass microfiber filter (grade GF/F; Whatman, U.S.) and Celgard 2400 as the separator, and 1 M NaClO4 in propylene carbonate as electrolyte. The batteries were cycled galvanostatically at room temperature.
Figure 2. SEM micrographs showing the morphology and particle size of (a) as-synthesized, (b) annealed, and (c) carbon-coated Na 1 . 70 2 Fe 3 (PO 4 ) 3 . (d) TEM image of an as-synthesized Na1.702Fe3(PO4)3 nanoplate. The SAED pattern is shown in the inset.
3. RESULTS AND DISCUSSION 3.1. Structural Parameters and Morphology of Na1.702Fe3(PO4)3. Alluaudite Na1.702Fe3(PO4)3 crystallizes in the monoclinic C2/c space group.22 The XRD pattern of an annealed sample indicates that pure alluaudite Na1.702Fe3(PO4)3 was obtained (Figure 1a). On the basis of the Reitveld refinement of the XRD data (Tables S1 and S2), the crystal structure of Na1.702Fe3(PO4)3 can be described as a framework consisting of Fe octahedral with bridging phosphate tetrahedral (Figure 1b). Two different channels are present in the crystal lattice where sodium ions can reside. These channels are parallel to the c-axis. Additional views of the crystal structure are shown in Figure S1. Shown in Figure 2a−c are SEM images of three samples of Na1.702Fe3(PO4)3: as-synthesized, annealed, and carbon-coated, respectively. On average, the length and width of the nanoplate is 2 μm and 200 nm, respectively. The carbon content of the
carbon-coated sample was 5 wt % as measured by a carbon− nitrogen elemental analyzer (CE Instruments Model NC2100). Shown in Figure 2d is a TEM image of an individual nanoplate of Na1.702Fe3(PO4)3. The crystalline nature of the assynthesized Na1.702Fe3(PO4)3 is confirmed by the selected area electron diffraction (SAED) pattern (inset), which is indexed to the monoclinic crystal structure along the [010] zone axis. This result indicates that the b-axis is perpendicular to the major facet shown with the a-axis and c-axis corresponding to the short and long edge of the crystalline nanoplate, respectively. 3.2. Performance of Na1.702Fe3(PO4)3 as Cathode Material. A sample of carbon-coated Na1.702Fe3(PO4)3 nanoplates was tested as a cathode material in a coin-cell battery. Charging and discharging profiles of a sodium-ion battery [Na metal∥Na1.702Fe3(PO4)3] are shown in Figure 3a. The sodiumion battery delivers a capacity of ∼60 mAh/g when discharged 5767
DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
Research Article
ACS Sustainable Chemistry & Engineering
Figure 3. (a) Voltage-capacity profiles during charging and discharging of a [Na∥Na1.702Fe3(PO4)3] battery at C/20 rate. A CC/CV (constant current to 4.4 V then constant voltage) charging procedure is used for the charging. (b) Cyclic voltammograms (CV) of Na1.702Fe3(PO4)3 measured at a scan rate of 0.1 mV/s (red) and 0.05 mV/s (black).
oxidizer (the potential of the NO2+/NO2 redox couple is 4.5 V vs Na+/Na28). An XRD pattern of the chemically desodiated material was measured and Rietveld refined (Figure S3) to reveal a new compound in the alluaudite class Na0.872Fe3(PO4)3. Refinement of the occupancy factors of the Na sites indicates that occupancy of Na(1) and Na(2) sites was reduced to 0 and 0.872, respectively (Tables S3 and S4). A comparison of the structures of Na0.872Fe3(PO4) 3 and Na1.702Fe3(PO4)3 reveals that all Na ions (0.754 Na ions per formula unit) that occupy the Na(1) site in channel 2 are extracted at potentials less than 4.5 V vs Na+/Na, whereas only a small portion of Na ions (0.076 Na ions) that occupy the Na(2) site in channel 1 are extracted at these potentials. This result can be explained by the difference in size of the two channels: channel 1 is slightly smaller than channel 2 (the shortest Na−O bond in channel 1 is shorter than in channel 2 by ∼6.3%22), and therefore, more energy is required to extract all Na ions from the Na(2) sites in channel 1. The thermal stability of pristine Na1.702Fe3(PO4)3 was tested by in situ temperature-dependent XRD between room temperature and 500 °C (Figure S4). Pristine Na1.702Fe3(PO4)3 exhibits excellent thermal stability as indicated by the absence of any change in the XRD at all temperatures tested. 3.3. Ball-Milling and Carbon-Coating of Na 1 . 7 0 2 Fe 3 (PO 4 ) 3 . A crystal of the as-synthesized Na1.702Fe3(PO4)3 was indexed in the TEM diffraction pattern (Figure 2d inset) to determine the orientation of the Na ion channels relative to the crystal facets. Indexing revealed the longest edge of the crystal corresponds to the c-axis of Na1.702Fe3(PO4)3 alluaudite structure, which is parallel to the Na ion channels. Consequently, the diffusion length for Na ions during charging and discharging is longer than 1 μm, which could explain the poor performance of the material in previous studies. Therefore, material samples were ball-milled to reduce their particle size and thus obtain better electrochemical performance.29 Shown in Figure 4a is an SEM micrograph of Na1.702Fe3(PO4)3 after ball-milling, where most particles are smaller than 200 nm. Shown in Figure 4b is an SEM micrograph of a ball-milled sample of Na1.702Fe3(PO4)3 after carbon coating. The TEM images show that particles of this sample are coated with carbon layers with thickness of ∼10 nm (Figure 4c and d). The XRD patterns of the after ball-milling samples show broader and lower-intensity peaks, which indicates that the crystallite size became smaller after the ballmilling process (Figure S5). The XRD peaks appear at the same 2⊖ values as the as-synthesized Na1.702Fe3(PO4)3, indicating
galvanostatically at room temperature. The difference in the charge profile of the first cycle compared to subsequent cycles may be caused by Na defects in the surface layer. Reconstruction of surface structure occurs during the first charging process, which leads to a larger polarization. Similar behavior has been observed in other Na-based cathode materials such as Na2FeP2O713 and olivine NaFePO4.23 The charge profiles in subsequent cycles exhibit very similar plateaus indicating that Na+ intercalation/deintercalation in this structure is highly reversible. Six different plateaus appear in the voltage-capacity curve, which correspond to peaks in the cyclic voltammetry data shown in Figure 3b. These peaks appear at six different potentials, indicating Na sites at different energy levels are involved in the electrochemical charging and discharging of Na1.702Fe3(PO4)3 (i.e., all peaks correspond to the Fe3+/Fe2+ redox couple with a concomitant Na+ insertion and extraction.) This type of multistep voltage-capacity curve indicates structural rearrangements and Na-ion ordering are involved in the electrochemical reaction of alluaudite Na1.702Fe3(PO4)3. Similar stepwise voltage-capacity curves have been observed in other Na-based cathode materials, such as P2−NaxCoO224 and Na2FeP2O7,13,25 implying the formation of distinct phases during the insertion and extraction of Na+. Broad peaks (labeled with black arrows in Figure 3b) at 2.53, 2.81, and 3.80 V suggest that single-phase reactions take place, whereas sharp peaks (labeled with green arrows in Figure 3b) at 2.12, 2.96, and 3.25 V are characteristic of biphasic transitions.26 CV data obtained at a lower scan rate (black line in Figure 3b) reveal the sharp peaks at 2.12, 2.96, and 3.25 V more clearly. These results indicate that both single-phase reactions and biphasic transitions occur in Na1.702Fe3(PO4)3 when cycled in a Na-ion battery. Similar results have been reported for Na2FeP2O7, where a single-phase transition and a series of two-phase transitions were observed in the CV and confirmed by first-principle calculations.13 It should be noted that the phase behavior observed here is very different from the behavior of solid solutions of alluaudites previously reported, which did not exhibit plateaus in their charging/discharging profiles and did not have a sharp peak in their CV profiles.10,11,27 The discharging capacity obtained at the 30th cycle (63.1 mAh/g) is much lower than the theoretical capacity (160 mAh/ g), where three Na ions are assumed to be electroactive per formula unit if the material is cycled between the two end states: FeIII(PO4)3 and Na3FeII(PO4)3. Chemical oxidation of the as-synthesized Na1.702Fe3(PO4)3 was performed using nitronium tetrafluoroborate (NO2BF4), which is a strong 5768
DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
Research Article
ACS Sustainable Chemistry & Engineering
material is much higher than that of the sample not carboncoated (2.88 vs 2.48 V). The improved battery performance including higher specific capacity, better cyclability, and higher average voltage of the ball-milled/carbon-coated sample can be explained by the increased electronic conductivity, smaller contact resistance between particles, and more ordered surface layer of the electrode material after carbon coating.33,34 As a result, the energy density for the ball-milled/carbon-coated Na1.702Fe3(PO4)3 cathode in a Na-ion battery is very high (405 Wh/kg). This value is close to the value for LiMn2O4 (∼430 Wh/kg) and comparable to the value for LiFePO4 (∼500 Wh/ kg) in Li-ion batteries. Importantly, fewer plateaus appear in the charging and discharging curves for the ball-milled/carbon-coated material compared to those of the sample that had not been ball-milled (Figure 3a). Only two broad peaks and two sharp peaks are present in the CV data (Figure S7), which indicates fewer phase transitions during cycling. The differences in extraction/ insertion behavior between samples can be interpreted as a decrease in the miscibility gap due to reduction of particle size to the nanoscale.35−38 In addition, the disorder of electrode materials introduced by the ball-milling process can influence the phase transition behavior as reported in the case of nanosized LiFePO4 upon cycling.39 In addition, Na1.702Fe3(PO4)3 crystals that have been ballmilled and carbon-coated exhibit excellent rate performance when compared with other known polyanion-type cathode materials proposed for Na-ion batteries (Figure 6). In theory, this alluaudite could perform better than carbon-coated LiFePO4 (in a Li-ion battery) and therefore is worth further study.
Figure 4. SEM micrographs showing the morphology and particle size of Na1.702Fe3(PO4)3 crystals after (a) ball-milling and (b) ball-milling and carbon-coating. (c) TEM image showing the carbon-coated particles of the ball-milled/carbon-coated Na1.702Fe3(PO4)3, and (d) high-resolution TEM image showing that the thickness of the carbon layer is ∼10 nm.
the alluaudite crystal structure remains unchanged. Electrochemical studies were performed on both samples as cathode materials in a Na-ion coin cell. The ball-milled sample shows a discharging capacity of 126.5 mAh/g for the first cycle (Figure 5a), which is much better than that of the sample not ball-milled. However, this cathode exhibits significant capacity fading to only 45 mAh/g by the 30th cycle (Figure 5b). The poor retention of capacity is likely because of decreased crystallinity and surface defects resulting from the ball-milling process. Improvement in battery performance is achieved after carbon coating of the ball-milled material. The ball-milled/carbon-coated material delivers a reversible capacity of 140.7 mAh/g at C/20 rate (8.2 mA/g), which is close to the theoretical capacity of Na1.702Fe3(PO4)3 (∼160 mAh/g). This capacity is the highest value reported for a Naion battery using an alluaudite-based cathode.6−10,14 The initial Coulombic efficiency is 80%. This efficiency may be related to surface reactions that lead to the formation of an SEI layer from electrolyte decomposition.20−32 Nevertheless, the Coulombic efficiency increases to over 90% with cycling (Figure S6). This battery exhibits very good capacity retention with 93% of the initial discharge capacity retained after 50 cycles (Figure 5b). In addition, the average voltage of the ball-milled/carbon-coated
4. CONCLUSIONS In summary, we report the synthesis, crystal structure, and electrochemical properties of an alluaudite phase of Na1.702Fe3(PO4)3 and demonstrate its potential as a cathode material in a Na-ion battery. This material was synthesized using a simple hydrothermal reaction at moderate temperature. With ball-milling and a carbon coating, Na1.702Fe3(PO4)3 exhibits exceptional electrochemical properties based on the Fe3+/Fe2+ redox couple. A preliminary study of the structural transition that occurs during the electrochemical cycling is reported. The partially desodiated compound, Na0.872Fe3(PO4)3, is obtained as a new alluaudite compound. Alluaudite Na1.702Fe3(PO4)3 could be a very promising cathode material for Na ion batteries that target large-scale applications because of its scalable and low cost synthesis, environmentally
Figure 5. (a) Voltage-capacity profile and (b) cycling performance at C/20 rate of Na1.702Fe3(PO4)3. 5769
DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
Research Article
ACS Sustainable Chemistry & Engineering Notes
The authors declare no competing financial interest.
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Figure 6. Rate performance of different polyanion-type cathode materials proposed for Na-ion batteries. Data corresponding to Na1.702Fe3(PO4)3 that has been ball-milled and carbon-coated is shown as a black line, and the corresponding theoretical performance is shown as a black dashed line (the corresponding charge/discharge profiles are provided in Figure S8). *Rate performance of olivine LiFePO4 in a Li-ion battery.
benign composition, high capacity (140.7 mAh/g), high energy density (405 Wh/kg), excellent rate capability, and good thermal stability.
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.7b00371. Figure S1, Alluaudite structure of Na1.702Fe3(PO4)3 viewed down (a) a axis and (b) b axis; Table S1, lattice parameters of Na 1.702Fe3(PO4)3 obtained by Rietveld refinement of XRD data; Table S2, atomic coordinates and site occupancies of Na1.702Fe3(PO4)3; Figure S2, charging and discharging profiles at C/20 rate for carbon-coated Na1.702Fe3(PO4)3; Figure S3, Rietveld refinement of the XRD pattern of Na0.872Fe3(PO4)3; Table S3, lattice parameters of Na0.872Fe3(PO4)3; Table S4, atomic coordinates and site occupancies of Na0.872Fe3(PO4)3; Figure S4, in situ high-temperature XRD patterns of (a) Na 1.702 Fe 3 (PO 4 ) 3 and (b) Na0.872Fe3(PO4)3; Figure S5, XRD patterns of before ball-milling and after ball-milling Na1.702Fe3(PO4)3; Figure S6, charging capacity, discharging capacity, and Coulombic efficiency of the ball-milled/carbon-coated Na1.702Fe3(PO4)3 at C/20 rate for 50 cycles; Figure S7a, cyclic voltammogram (CV) of ball-milled/carbon-coated Na1.702Fe3(PO4)3 electrode measured at a scan rate of 0.1 mV/s; Figure S7b, dQ/dV curve of charge−discharge profile of ball-milled/carbon-coated Na1.702Fe3(PO4)3 in a Na-ion cell; Figure S8, charge/discharge profiles of ballmilled/carbon-coated Na1.702Fe3(PO4)3 electrode measured at different discharge C rates; *CC/CV (constant current at C/20 to 4.4 V then constant voltage) charging procedure is used for all of the charging (PDF)
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REFERENCES
(1) Palomares, V.; Serras, P.; Villaluenga, I.; Hueso, K. B.; CarreteroGonzález, J.; Rojo, T. Na-ion batteries, recent advances and present challenges to become low cost energy storage systems. Energy Environ. Sci. 2012, 5, 5884−5901. (2) Tarascon, J. M.; Armand, M. Issues and challenges facing rechargeable lithium batteries. Nature 2001, 414, 359−367. (3) Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. A multifunctional 3.5 V iron-based phosphate cathode for rechargeable batteries. Nat. Mater. 2007, 6, 749−753. (4) Yabuuchi, N.; Kubota, K.; Dahbi, M.; Komaba, S. Research development on sodium-ion batteries. Chem. Rev. 2014, 114, 11636− 11682. (5) Ong, S. P.; Chevrier, V. L.; Hautier, G.; Jain, A.; Moore, C.; Kim, S.; Ma, X.; Ceder, G. Voltage, stability and diffusion barrier differences between sodium-ion and lithium-ion intercalation materials. Energy Environ. Sci. 2011, 4, 3680−3688. (6) Ellis, B. L.; Makahnouk, W. M.; Rowan-Weetaluktuk, W. N.; Ryan, D. H.; Nazar, L. F. Crystal Structure and Electrochemical Properties of A2MPO4F Fluorophosphates (A= Na, Li; M= Fe, Mn, Co, Ni). Chem. Mater. 2009, 22, 1059−1070. (7) Recham, N.; Chotard, J. N.; Dupont, L.; Djellab, K.; Armand, M.; Tarascon, J. M. Ionothermal synthesis of sodium-based fluorophosphate cathode materials. J. Electrochem. Soc. 2009, 156, A993−A999. (8) Moreau, P.; Guyomard, D.; Gaubicher, J.; Boucher, F. Structure and stability of sodium intercalated phases in olivine FePO4. Chem. Mater. 2010, 22, 4126−4128. (9) Lee, K. T.; Ramesh, T. N.; Nan, F.; Botton, G.; Nazar, L. F. Topochemical synthesis of sodium metal phosphate olivines for sodium-ion batteries. Chem. Mater. 2011, 23, 3593−3600. (10) Chen, H.; Hautier, G.; Ceder, G. Synthesis, computed stability, and crystal structure of a new family of inorganic compounds: carbonophosphates. J. Am. Chem. Soc. 2012, 134, 19619−19627. (11) Kim, H.; Park, I.; Seo, D. H.; Lee, S.; Kim, S. W.; Kwon, W. J.; Park, Y. U.; Kim, C. S.; Jeon, S.; Kang, K. New iron-based mixedpolyanion cathodes for lithium and sodium rechargeable batteries: combined first principles calculations and experimental study. J. Am. Chem. Soc. 2012, 134, 10369−10372. (12) Kim, H.; Shakoor, R. A.; Park, C.; Lim, S. Y.; Kim, J. S.; Jo, Y. N.; Cho, W.; Miyasaka, K.; Kahraman, R.; Jung, Y.; Choi, J. W. Na2FeP2O7 as a Promising Iron-Based Pyrophosphate Cathode for Sodium Rechargeable Batteries: A Combined Experimental and Theoretical Study. Adv. Funct. Mater. 2013, 23, 1147−1155. (13) Barpanda, P.; Liu, G.; Ling, C. D.; Tamaru, M.; Avdeev, M.; Chung, S. C.; Yamada, Y.; Yamada, A. Na2FeP2O7: a safe cathode for rechargeable sodium-ion batteries. Chem. Mater. 2013, 25, 3480−3487. (14) Barpanda, P.; Ye, T.; Avdeev, M.; Chung, S. C.; Yamada, A. A new polymorph of Na2MnP2O7 as a 3.6 V cathode material for sodium-ion batteries. J. Mater. Chem. A 2013, 1, 4194−4197. (15) Chen, H.; Hao, Q.; Zivkovic, O.; Hautier, G.; Du, L. S.; Tang, Y.; Hu, Y. Y.; Ma, X.; Grey, C. P.; Ceder, G. Sidorenkite (Na3MnPO4CO3): a new intercalation cathode material for Na-ion batteries. Chem. Mater. 2013, 25, 2777−2786. (16) Barpanda, P.; Oyama, G.; Nishimura, S. I.; Chung, S. C.; Yamada, A. A 3.8-V earth-abundant sodium battery electrode. Nat. Commun. 2014, 5, 54538. (17) Richardson, T. J. Phosphate-stabilized lithium intercalation compounds. J. Power Sources 2003, 54, 262−265. (18) Trad, K.; Carlier, D.; Croguennec, L.; Wattiaux, A.; Ben Amara, M.; Delmas, C. NaMnFe2 (PO4)3 alluaudite phase: synthesis, structure, and electrochemical properties as positive electrode in lithium and sodium batteries. Chem. Mater. 2010, 22, 5554−5562. (19) Trad, K.; Carlier, D.; Croguennec, L.; Wattiaux, A.; Ben Amara, M.; Delmas, C. Structural study of the Li0.5Na0.5MnFe2(PO4) and Li0.75Na0.25MnFe2(PO4)3 alluaudite phases and their electrochemical
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G. Tayhas R. Palmore: 0000-0001-8045-6064 5770
DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
Research Article
ACS Sustainable Chemistry & Engineering properties as positive electrodes in lithium batteries. Inorg. Chem. 2010, 49, 10378−10389. (20) Kim, J.; Kim, H.; Park, I.; Park, Y. U.; Yoo, J. K.; Park, K. Y.; Lee, S.; Kang, K. LiFePO4 with an alluaudite crystal structure for lithium ion batteries. Energy Environ. Sci. 2013, 6, 830−834. (21) Kim, J.; Kim, H.; Park, K. Y.; Park, Y. U.; Lee, S.; Kwon, H. S.; Yoo, H. I.; Kang, K. Alluaudite LiMnPO4: a new Mn-based positive electrode for Li rechargeable batteries. J. Mater. Chem. A 2014, 2, 8632−8636. (22) Hatert, F.; Rebbouh, L.; Hermann, R. P.; Fransolet, A. M.; Long, G. J.; Grandjean, F. Crystal chemistry of the hydrothermally synthesized Na2 (Mn1‑xFex 2+)2Fe3+ (PO4)3 alluaudite-type solid solution. Am. Mineral. 2005, 90, 653−662. (23) Fang, Y.; Liu, Q.; Xiao, L.; Ai, X.; Yang, H.; Cao, Y. HighPerformance Olivine NaFePO4 Microsphere Cathode Synthesized by Aqueous Electrochemical Displacement Method for Sodium Ion Batteries. ACS Appl. Mater. Interfaces 2015, 7, 17977−17984. (24) Carlier, D.; Cheng, J. H.; Berthelot, R.; Guignard, M.; Yoncheva, M.; Stoyanova, R.; Hwang, B. J.; Delmas, C. The P2Na2/3Co2/3Mn1/3O2 phase: structure, physical properties and electrochemical behavior as positive electrode in sodium battery. Dalton Trans. 2011, 40, 9306−9312. (25) Barpanda, P.; Ye, T.; Nishimura, S. I.; Chung, S. C.; Yamada, Y.; Okubo, M.; Zhou, H.; Yamada, A. Sodium iron pyrophosphate: A novel 3.0 V iron-based cathode for sodium-ion batteries. Electrochem. Commun. 2012, 24, 116−119. (26) Sauvage, F.; Laffont, L.; Tarascon, J. M.; Baudrin, E. Study of the insertion/deinsertion mechanism of sodium into Na0.44MnO2. Inorg. Chem. 2007, 46, 3289−3294. (27) Huang, W.; Zhou, J., Li, B.; An, L.; Xia, D.; Chu, W.; Wu, Z. Monodisperse Porous Na2Fe3(PO4)3 Nanocomposites for a New High Energy Sodium Ion Battery Cathodes; Meeting Abstracts #191, Electrochemical Conference on Energy & the Environment (ECEE); The Electrochemical Society, 2014; no. 2, pp 191−191. (28) Wizansky, A. R.; Rauch, P. E.; Disalvo, F. J. Powerful oxidizing agents for the oxidative deintercalation of lithium from transitionmetal oxides. J. Solid State Chem. 1989, 81, 203−207. (29) Chen, H.; Hautier, G.; Jain, A.; Moore, C.; Kang, B.; Doe, R.; Wu, L.; Zhu, Y.; Tang, Y.; Ceder, G. Carbonophosphates: a new family of cathode materials for Li-ion batteries identified computationally. Chem. Mater. 2012, 24, 2009−2016. (30) Cao, Y.; Xiao, L.; Wang, W.; Choi, D.; Nie, Z.; Yu, J.; Saraf, L. V.; Yang, Z.; Liu, J. Reversible sodium ion insertion in single crystalline manganese oxide nanowires with long cycle life. Adv. Mater. 2011, 23, 3155−3160. (31) Song, J.; Xu, M.; Wang, L.; Goodenough, J. B. Exploration of NaVOPO4 as a cathode for a Na-ion battery. Chem. Commun. 2013, 49, 5280−5282. (32) Nose, M.; Shiotani, S.; Nakayama, H.; Nobuhara, K.; Nakanishi, S.; Iba, H. Na4Co2.4Mn0.3Ni0.3(PO4)2P2O7: High potential and high capacity electrode material for sodium-ion batteries. Electrochem. Commun. 2013, 34, 266−269. (33) Wang, J.; Sun, X. Understanding and recent development of carbon coating on LiFePO4 cathode materials for lithium-ion batteries. Energy Environ. Sci. 2012, 5, 5163−5185. (34) Zaghib, K.; Charest, P.; Dontigny, M.; Guerfi, A.; Lagacé, M.; Mauger, A.; Kopec, M.; Julien, C. M. LiFePO4: from molten ingot to nanoparticles with high-rate performance in Li-ion batteries. J. Power Sources 2010, 195, 8280−8288. (35) Delacourt, C.; Poizot, P.; Tarascon, J. M.; Masquelier, C. The existence of a temperature-driven solid solution in LixFePO4 for 0≤ x≤ 1. Nat. Mater. 2005, 4, 254−260. (36) Yamada, A.; Koizumi, H.; Nishimura, S. I.; Sonoyama, N.; Kanno, R.; Yonemura, M.; Nakamura, T.; Kobayashi, Y. Roomtemperature miscibility gap in LixFePO4. Nat. Mater. 2006, 5, 357− 360. (37) Meethong, N.; Huang, H. Y. S.; Speakman, S. A.; Carter, W. C.; Chiang, Y. M. Strain Accommodation during Phase Transformations in Olivine-Based Cathodes as a Materials Selection Criterion for High-
Power Rechargeable Batteries. Adv. Funct. Mater. 2007, 17, 1115− 1123. (38) Gibot, P.; Casas-Cabanas, M.; Laffont, L.; Levasseur, S.; Carlach, P.; Hamelet, S.; Tarascon, J. M.; Masquelier, C. Room-temperature single-phase Li insertion/extraction in nanoscale LixFePO4. Nat. Mater. 2008, 7, 741−747. (39) Julien, C. M.; Mauger, A.; Zaghib, K. Surface effects on electrochemical properties of nano-sized LiFePO4. J. Mater. Chem. 2011, 21, 9955−9968.
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DOI: 10.1021/acssuschemeng.7b00371 ACS Sustainable Chem. Eng. 2017, 5, 5766−5771
