The study of K2FeO4 (Fe6+-super iron compound) as a cathode material for rechargeable lithium batteries

Koltypin, Maxim; Licht, Stuart; Vered, R.; Nashits, Vera; Aurbach, Doron

doi:10.1016/j.jpowsour.2005.03.163

Cited by 15 publications

(4 citation statements)

References 7 publications

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“…It is evident in Figure that potential variations during both the charge and discharge processes are smooth; that is, there are no evident demarcations between the first, second, or third electron equivalents of oxidation or reduction during the film charge or discharge. In similar discharge conditions, Koltypin found that the discharge capacity can be slightly higher than the charge capacity due to the reduction of electrolyte (propylene carbonate) when very low discharge potentials are permitted (1.5 V vs Li/Li + ). In our experiments, the cutoff potential was normally over 2.0 V, and hence no evidence of electrolyte (PC) reduction was observed.…”

Section: Resultsmentioning

confidence: 98%

Enhancement of Reversible Nonaqueous Fe(III/VI) Cathodic Charge Transfer

2009

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The electrochemical preparation of Fe(III/VI) super-iron thin films cathodes on an extended conductive matrix significantly facilitates such film’s nonaqueous, reversible charge transfer. Fe(VI) salts can exhibit higher cathodic capacity and environmental advantages, and the films are of relevance toward the next generation charge storage chemistry for reversible cathodes. These films were electrochemically deposited on either smooth or platinized platinum by electrochemical reduction of Na2FeO4, which retains an intrinsic 3 e− cathodic charge storage capacity of 485 mAh g−1. The influence on cathode reversibility, capacity, and charge retention was probed as function of film deposition conditions (including the deposition potential and stirring rate, and the concentration of NaOH and K2FeO4, in the deposition electrolyte). The highest storage capacity films were formed from an 8.0 M NaOH electrolyte containing 50.0 mM of K2FeO4 and examined by FTIR. Those “super-iron” cathode films, which are up to 191 nm thick and electrodeposited on smooth platinum, sustained up to 300 reversible three-electron galvanostatic charge/discharge cycles to a high depth of discharge in 1 M LiPF6 in PC:DME electrolyte lithium cells. Thicker (greater than 500 nm thick) films deposited on smooth platinum evidence increasing passivity to Fe(VI) charge transfer and charge storage. Films deposited on platinized platinum overcome this passivity, permitting sustained nonaqueous charge/discharge cycling with a thicker (571 nm) Fe(VI) film cathode, and provide a first demonstration of significant Fe(VI)/lithium thin-film secondary cell behavior.

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Section: Resultsmentioning

confidence: 98%

Enhancement of Reversible Nonaqueous Fe(III/VI) Cathodic Charge Transfer

2009

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“…7 and 8͒, and the iron-nickel battery ͑e.g., Ref. 9 and 10͒. Only a few studies have described the use of hot caustic solutions to grow protective iron oxides on steel.…”

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confidence: 99%

Properties of the Nanoporous Anodic Oxide Electrochemically Grown on Steel in Hot 50% NaOH

Burleigh

Schmuki

Virtanen

2009

J. Electrochem. Soc.

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The anodic oxide grown on steel in 50% NaOH at different temperatures and applied potentials has many remarkable properties. Optically the appearance of the oxide can vary from black to dichroic, to a light brown color. Field-effect scanning electron microscopy and X-ray diffraction reveal the oxide to be a nanoporous oxide composed of a network of 100 nm diam magnetite channels. Electrochemically the oxide is a very good conductor and, when polarized cathodic or anodic, can absorb charge by switching between Fe +2 and Fe +3 . Although the film provides excellent corrosion resistance in pure water, it provides only temporary resistance to corrosion in oxygenated saltwater. Different methods were used to seal the porous oxide, and it was found possible to reduce the corrosion rate by 2 orders of magnitude in oxygenated 0.1% NaCl solution by penetrating the oxide with a commercial inhibiting oil spray.Anodization of metals is an old and relatively simple method to functionalize material surfaces, by electrochemically growing a metal oxide film on the surface. For valve metals such as Al, Ti, Ta, or Zr, anodization has been extensively explored and, by a controlled variation of the electrochemical parameters used, the thickness, morphology ͑e.g., compact or porous layers͒, or crystal structure of the anodic films can be tailored to achieve the desired functionality. As for the valve metals, high voltages can be applied without substantial oxygen evolution reaction ͑OER͒ and thick anodic oxide layers can be grown before dielectric breakdown occurs. However, in the case of iron or steel, strong oxygen evolution at high anodic potentials takes place and, hence, the potential regime of oxide growth is limited.As has been reported previously by Burleigh, in spite of oxygen evolution ͑and, hence, lower current efficiency͒, thick anodic oxide layers can be grown on steel in hot, concentrated caustic solutions in the transpassive region. 1 The present article presents a continuation of the previous work, with the aim to understand the growth mechanisms, to analyze and optimize different properties of the anodic oxide layer, and to explore the use of the anodic layer for corrosion protection of steel. This is a relatively new field of research even though there have been many diverse studies on the electrochemical behavior of steel in caustic solutions. For example, previous studies include the dissolution and passivation of iron and steel ͑e.g., Ref.2-6͒, the production of ferrate ͑VI͒ compounds ͑e.g., Ref. 7 and 8͒, and the iron-nickel battery ͑e.g., Ref. 9 and 10͒. Only a few studies have described the use of hot caustic solutions to grow protective iron oxides on steel. 1,11-14 Burleigh has shown that when steel was polarized in the transpassive region, the applied electric current promoted the growth of a magnetite ͑Fe 3 O 4 ͒ film in addition to oxygen evolution and iron dissolution. 1 This magnetite film has many different optical appearances, including black, dichroic, and a light brown color, depending on the temper...

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“…From the analysis of the results obtained by ultraviolet and visible spectroscopy, FTIR, scanning electron microscopy, X-ray diffraction and magnetometry, it allowed us to conclude that all samples (named as Type1, ferrate ions present high potential for technological application in several scientific areas, such as in the degradation of environmental pollutants and as disinfectants [54]. Furthermore, recent studies indicate that FeO 4 −2 ions have promising applications as electrolytes materials in rechargeable batteries [55].…”

Section: Resultsmentioning

confidence: 92%

Laser Ablation in Liquid: An Unconventional, Fast, Clean and Straightforward Technique for Material Preparation

Azevêdo¹,

Campello²,

Cunha³

et al. 2016

Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification

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The laser ablation in liquid environment (LALE) technique is a straightforward experimental technique with few controllable parameters, capable to provide extreme pressure and temperature conditions during target ablation without the need for dedicated systems to provide those variables. Additionally, we can state that LALE can be considered a low-cost experimental technique, with few steps and a clean synthesis method, by which a wide variety of materials can be synthesized with high yield. The majority of studies published in the literature using this technique seem to be limited only to the synthesis of metal nanoparticles, metal oxides, nitrates and semiconducting. However, in order to extend the synthesis potential of this technique, in this chapter we are going to demonstrate that with the appropriate choice of reactants, solvent, target materials and the solid-liquid interface interactions we will be able to prepare more complex molecules such as carbonate compound Pb 3 (CO 3) 2 (OH) 2 , metal-organic frameworks (MOFs), luminescent metal-organic frameworks (LMOFs), highly dispersed CdS quantum dots and magnetic materials. Also for each material synthesized, we are going to propose a mechanism to explain its preparation using the LALE technique.

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The study of K2FeO4 (Fe6+-super iron compound) as a cathode material for rechargeable lithium batteries

Cited by 15 publications

References 7 publications

Enhancement of Reversible Nonaqueous Fe(III/VI) Cathodic Charge Transfer

Enhancement of Reversible Nonaqueous Fe(III/VI) Cathodic Charge Transfer

Properties of the Nanoporous Anodic Oxide Electrochemically Grown on Steel in Hot 50% NaOH

Laser Ablation in Liquid: An Unconventional, Fast, Clean and Straightforward Technique for Material Preparation

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