Amorphous FePO4 as 3 V cathode material for lithium secondary batteries

Hong, Young-Shick; Ryu, Kwang Sun; Park, Yong Joon; Kim, Min; Lee, Jay Min; Chang, Seung‐Hwan

doi:10.1039/b200901c

Cited by 98 publications

(68 citation statements)

References 15 publications

(26 reference statements)

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“…A slight shift of the broad diffraction peak toward lower angles is observed at higher temperatures, which is most likely due to the water content in the asprepared sample. 28 The thermogravimetric analysisA of the asprepared sample reveals a weight loss of 9 wt% (Supplementary Figure S2) until 250°C, and no significant loss (∼1.7 wt%) is observed between 250 and 500°C. Additionally, it has been reported that temperatures of 200°C are sufficient to ensure the removal of water from hydrated iron phosphates.…”

Section: Resultsmentioning

confidence: 99%

Amorphous iron phosphate: potential host for various charge carrier ions

et al. 2014

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In response to the ever-increasing global demand for viable energy-storage systems, sodium and potassium batteries appear to be promising alternatives to lithium ion batteries because of the abundance, low cost and environmental benignity of sodium/ potassium. Electrical energy storage via ion-intercalation reactions in crystalline electrodes is critically dependent on the sizes of the guest ions. Herein, we report on the use of a porous amorphous iron phosphate synthesized using ambient temperature strategies as a potential host that stores electrical energy through the feasible insertion of mono-/di-/tri-valent ions. A combination of ex situ studies reveals the existence of a reversible amorphous-to-crystalline transition in this versatile electrode during electrochemical reactions with monovalent sodium, potassium and lithium. This reconstitutive reaction contributes to realizing specific capacities of 179 and 156 mAhg − 1 versus sodium and potassium at current densities of 10 and 5 mAg − 1 , respectively. This finding facilitates the feasible development of several amorphous electrodes with similar phase behavior for energy-storage applications. NPG Asia Materials (2014) 6, e138; doi:10.1038/am.2014.98; published online 17 October 2014 INTRODUCTIONSince 1990, the global demand for electricity has increased twice as much as the demand for energy overall, and the demand for electricity is expected to further increase by more than two-thirds over the next 20 years. Energy storage/conversion technologies have therefore become a crucial research topic as we seek to make society sustainable. In particular, electrical energy storage is critical not only for supporting electronic, vehicular and load-leveling applications but also for efficiently commercializing renewable solar and wind power. Rechargeable Li-ion batteries with an output energy exceeding 90% have emerged as one of the most effective electrochemical energystorage technologies, and these batteries power most modern-day electronic devices. 1 Despite substantial research to enhance Li-ion batteries for high-power applications, aspects such as their availability, cost and safety still remain to be fully addressed. 2 The controversies surrounding the accessible global lithium reserves and the anticipated energy demand may greatly impact the cost of Li-ion batteries in the long term. 3 Although advancing Li-ion battery technologies for electric vehicle applications is attractive, the quest for alternative energy sources for smart grid-scale storage applications has recently gained significant momentum. Rechargeable sodium and potassium batteries offer tremendous potential because they utilize inexpensive, abundant and environmentally benign sodium/potassium elements. [4][5][6][7][8][9] However,

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Section: Resultsmentioning

confidence: 99%

Amorphous iron phosphate: potential host for various charge carrier ions

et al. 2014

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“…In addition to the peaks due to the Al foil, we did not observe any obvious peaks due to the reduction/oxidation of the cathode materials, indicating that the FePO 4 sample remained mostly amorphous during its interaction with Na + . 33 We, thereafter, tested the battery performance of the shell-controlled MWCNTs@FePO 4 samples to gain a better understanding of the structure-performance relationship. For comparison, a sample denoted as FePO 4 -MWCNTs was prepared by simply mixing the solid nanoparticles of FePO 4 and MWCNTs.…”

Section: Resultsmentioning

confidence: 99%

Kinetically controlled formation of uniform FePO4 shells and their potential for use in high-performance sodium ion batteries

et al. 2017

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Amorphous iron phosphates are potential cathode materials for sodium ion batteries. The amorphous FePO 4 matrix is able to insert/extract sodium ions reversibly without apparent structural degradation, resulting in stable performance during the charge/discharge process. However, the extremely low electronic conductivity of FePO 4 itself becomes a formidable obstacle for its application as a high-performance cathode material. Here, by tuning the growth kinetics of FePO 4 in an aqueous solution, we were able to control its formation onto a large variety of substrates, forming uniform core-shell structures. Specifically, the use of multiwalled carbon nanotubes as the core material together with the growth control of FePO 4 produced the core-shell structure of MWCNTs@FePO 4 with a delicately controlled shell thicknesses. We confirmed that such a nanocomposite can act as an effective cathode material by taking advantage of both the highly conductive core and the electrochemically active shell, leading to improved battery performance as revealed by the high discharge capacity and the greatly improved rate capability. We anticipate that our progress in FePO 4 control offers new potential in different research fields, such as materials chemistry, catalysis and energy storage devices.

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“…For example, a prior report yielded a cycle 2 specific discharge capacity of 76 mAh/g for an amorphous FePO 4 ·2H 2 O material, but only 18 mAh/g for a more crystalline hexagonal FePO 4 material prepared at 500 °C [35]. Similarly, carbon nanotube-amorphous FePO 4 core-shell NWs realized a specific capacity of 175 mAh/g in lithium batteries [36] and 120 mAh/g in sodium batteries [37], respectively, but with ultra-thin amorphous coatings of FePO 4 comprising only a few nm in thickness.…”

Section: Introductionmentioning

confidence: 96%

Ambient synthesis, characterization, and electrochemical activity of LiFePO4 nanomaterials derived from iron phosphate intermediates

et al. 2015

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LiFePO 4 materials have become increasingly popular as a cathode material due to the many benefits they possess including thermal stability, durability, low cost, and long life span. Nevertheless, to broaden the general appeal of this material for practical electrochemical applications, it would be useful to develop a relatively mild, reasonably simple synthesis method of this cathode material. Herein, we describe a generalizable, 2-step methodology of sustainably synthesizing LiFePO 4 by incorporating a template-based, ambient, surfactantless, seedless, U-tube protocol in order to generate size and morphologically tailored, crystalline, phase-pure nanowires. The purity, composition, crystallinity, and intrinsic quality of these wires were systematically assessed using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), selected area electron diffraction (SAED), energy dispersive analysis of X-rays (EDAX), and high-resolution synchrotron XRD. From these techniques, we were able to determine that there is an absence of any obvious defects present in our wires, supporting the viability of our synthetic approach. Electrochemical analysis was also employed to assess their electrochemical activity. Although our nanowires do not contain any noticeable impurities, we attribute their less than optimal electrochemical rigor to differences in the chemical bonding between our LiFePO 4 nanowires and their bulk-like counterparts. Specifically, we demonstrate for the first time experimentally that the Fe-O3 chemical bond plays an important role in determining the overall conductivity of the material, an assertion which is further supported by recent "first-principles" calculations. Nonetheless, our ambient, solution-based synthesis technique is capable of generating highly crystalline and phase-pure energy-storage-relevant nanowires that can be tailored so as to fabricate different sized materials of reproducible, reliable morphology.

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Amorphous FePO4 as 3 V cathode material for lithium secondary batteries

Cited by 98 publications

References 15 publications

Amorphous iron phosphate: potential host for various charge carrier ions

Amorphous iron phosphate: potential host for various charge carrier ions

Kinetically controlled formation of uniform FePO4 shells and their potential for use in high-performance sodium ion batteries

Ambient synthesis, characterization, and electrochemical activity of LiFePO4 nanomaterials derived from iron phosphate intermediates

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