Fast discharge process of layered cobalt oxides due to high Na+ diffusion

Shibata, Takayuki; Fukuzumi, Yuya; Kobayashi, Wataru; Moritomo, Yutaka

doi:10.1038/srep09006

Cited by 85 publications

(60 citation statements)

References 24 publications

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“…In the as-grown film, intense 003 H and 006 H reflections are observed, indicating the 001-orientation of the films. We confirmed that the lattice constant c (=15.6 Å) of the as-grown film is consistent with the value (=15.58698(11) Å [9]) of the O3 phase. In the 2.3 V and 1.5 V films, the corresponding reflections shift to the low-2θ side, indicating widening of the interlayer distance.…”

Section: Introductionsupporting

confidence: 73%

“…With use of the ideal capacity, we converted the discharge capacity into x and plotted the value on the upper axis. The capacity of the O3-NaCoO 2 film slightly decreases with increase in the discharge rate, even at ∼1C [9]: 116 mAh/g at 0.2C, 100 mAh/g at 1.2C, and 82 mAh/g at 12C. Then, the x value may be slightly overestimated.…”

Section: Introductionmentioning

confidence: 92%

“…A thin film of O3-NaCoO 2 was prepared by pulsed laser deposition (PLD) method [9]. The film was grown on Au-deposited MgO (100) substrate at 823 K in an oxygen partial pressure of 0.01 Pa for 20 min.…”

Section: Film Preparation and Characterizationmentioning

confidence: 99%

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Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

et al. 2017

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O3-NaCoO 2 is a promising cathode material for sodium ion secondary batteries (SIBs). Na x CoO 2 shows phase separation (PS) into the O3 and O 3 phases in the Na concentration range of 0.89 x 0.99. In order to estimate the domain size (r) in the two-phase region, we performed X-ray microdiffraction (XRMD) of thin films of Na x CoO 2 at x = 0.97 and ∼1. We found that r (≈400 nm) of the O 3 domain is comparable to the particle size d (=331 ± 87 nm) in the as-grown O3-NaCoO 2 film. This observation suggests that individual particles of Na x CoO 2 are single phase to minimize the strain at the O3-O 3 phase boundary.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 92%

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Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

et al. 2017

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“…Reproduced with permission. [ 34 ] Copyright 2015, Nature Publishing Group. Potentiostatic intermittent titration technique (PITT) plot (left) and evolution of diffusion coeffi cient (D) with depths of discharge (right) of e) Na 0.73 CoO 2 and f) Na 0.60 Ca 0.07 CoO 2 , respectively.…”

Section: (4 Of 38)mentioning

confidence: 99%

Recent Progress in Electrode Materials for Sodium‐Ion Batteries

Kim

Zhang

et al. 2016

Advanced Energy Materials

885

595

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Grid‐scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever‐growing energy demands. Although recent advances in Li‐ion battery (LIB) technology have increased the energy density to a level applicable to grid‐scale ESSs, the high cost of Li and transition metals have led to a search for lower‐cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well‐established LIB technology, Na‐ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid‐scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed.

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“…In Figure 4b, specific energies of TFCN achieved in 2-4.2 V as a function of the C-rate are plotted with those of other O3-NaMO 2 for comparison. 4,9,10,[19][20][21] TFCN indeed exhibits superior electrochemical performance: the specific energies achieved are 504 Wh/kg at C/20 and 200 Wh/kg at 30 C, outperforming many O3-NaMO 2 compounds.…”

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confidence: 99%

Communication—O3-Type Layered Oxide with a Quaternary Transition Metal Composition for Na-Ion Battery Cathodes: NaTi_0.25Fe_0.25Co_0.25Ni_0.25O₂

Vassilaras

Dacek

Fister

et al. 2017

J. Electrochem. Soc.

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NaTi 0.25 Fe 0.25 Co 0.25 Ni 0.25 O 2 is explored as a cathode material for Na-ion batteries. Synthesized by a solid-state reaction, the compound is phase-pure with the O3-type layered structure and consists of Ti 4+ , Fe 3+ , Co 3+ , and Ni 2+ according to X-ray absorption spectroscopy. The cathode delivers 163 mAh/g and 504 Wh/kg at C/20 in the first discharge with 89% capacity retention after 20 cycles and demonstrates superior rate capability with micron sized particles, in which discharge capacity at 30 C is 80 mAh/g. Our results indicate that the Ti-containing quaternary material can be a potential cathode composition for Na-ion batteries. Rechargeable batteries that reversibly cycle Na ions are a costeffective alternative to the Li-based technology to meet increasing demand and need for grid-level energy storage.1 Unlike Li cathode chemistries that heavily rely on Co and Ni, Na-intercalating oxides tend to form energy-dense layered structures with almost all transition metals including Cu, 2-4 allowing a broad selection and combination of redox centers to tune electrochemical properties and air-stability. In particular, Fe is an attractive metal due to its high redox potential and natural abundance.5 However, the performance of layered NaFeO 2 as a cathode is impractical; Fe 4+ migration upon desodiation destabilizes the structure, leading to poor Na ion mobility and irreversibility. 6 The charged state stability of the layered structure, and thereby their electrochemical properties, 7 can be enhanced by partially substituting Fe into redox-inactive elements and/or other transition metals.8-11 Li et al. proposed an optimal Fe content (< ∼33%) that promotes Na diffusion at the high state of charge.12,13 Here, we use Ti 4+ as a structural stabilizer and report an O3-type 14 Na transition metal oxide (O3-NaMO 2 ) composition, NaTi 0.25 Fe 0.25 Co 0.25 Ni 0.25 O 2 (TFCN), for the optimized Fe redox activity. Our results demonstrate a substantial amount of reversible Na intercalation and high rate capability of TFCN, implying that the material may be successfully used as a Na-ion battery cathode. MethodsA stoichiometric amount of transition metal precursors (TiO 2 , Fe 2 O 3 , Co 3 O 4 , and NiCO 3 , all from Sigma-Aldrich) were mixed with 20% excess Na 2 O (Sigma-Aldrich) by planetary ballmilling at 500 rpm for 4 hours. The resulting mixture was fired at 900• C for 12 hours under flowing O 2 , quenched to room temperature, and transferred to an Ar-filled glove box to prevent air-exposure. The crystal structure and particle morphology of as-prepared TFCN were analyzed by X-ray diffraction (XRD, PANalytical X'Pert Pro) with Rietveld refinement and scanning electron microscopy (SEM, Zeiss Merlin), respectively. Transition metal oxidation states were probed by X-ray absorption spectroscopy (XAS) obtained at Advanced Photon Source (13ID-E) in Argonne National Laboratory. For half-cell tests, cathodes were prepared by mixing the active material, Super P (Timcal) carbon, and polytetrafluoroethylene (Dupont) binder i...

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Fast discharge process of layered cobalt oxides due to high Na+ diffusion

Cited by 85 publications

References 24 publications

Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

Recent Progress in Electrode Materials for Sodium‐Ion Batteries

Communication—O3-Type Layered Oxide with a Quaternary Transition Metal Composition for Na-Ion Battery Cathodes: NaTi_0.25Fe_0.25Co_0.25Ni_0.25O₂

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Fast discharge process of layered cobalt oxides due to high Na+ diffusion

Cited by 85 publications

References 24 publications

Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

Recent Progress in Electrode Materials for Sodium‐Ion Batteries

Communication—O3-Type Layered Oxide with a Quaternary Transition Metal Composition for Na-Ion Battery Cathodes: NaTi0.25Fe0.25Co0.25Ni0.25O2

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Communication—O3-Type Layered Oxide with a Quaternary Transition Metal Composition for Na-Ion Battery Cathodes: NaTi_0.25Fe_0.25Co_0.25Ni_0.25O₂