Nanostructured and nanoporous LiFePO4 and LiNi0.5Mn1.5O4-δ as cathode materials for lithium-ion batteries

Kraas, Sebastian; Vijn, Annalena; Falk, Mareike; Ufer, Boris; Luerßen, Bjoern; Janek, Jürgen; Fröba, Michael

doi:10.1016/j.progsolidstchem.2014.04.014

Cited by 19 publications

(10 citation statements)

References 84 publications

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“…The red shift of the binding energy of V in LVP-0.10 suggests the mixed valence state of V 2þ and V 3þ , which may facilitate the electron hopping and increase the electronic conductivity [27]. Although we controlled off stoichiometry in LVP by keeping the balance of chemical valence state, the concentration of oxygen may change actually, leading to the valence change of V, which was attributed to oxygen deficiency [33]. Because of Li deficiency and V excess, and the different bond length between oxygen and metal ion, the occupied octahedral sites are distorted.…”

Section: Resultsmentioning

confidence: 99%

“…If the crystal shows an oxygen deficiency, the missing negative charge has to be balanced by the reduction of V from þ3 to þ2. The change in size of the V ions (V 2þ ) leads to a minimization of strain in the structure, similar to the LiNi 0.5 Mn 1.5 O 4 [33]. However, the possible surface layer with different composition to the bulk might exist, since XPS is only a surface sensitive technique [34].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Sun

Qin

Wang

et al. 2015

Journal of Power Sources

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Sun

Qin

Wang

et al. 2015

Journal of Power Sources

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“…The composite electrodes were prepared with 70% LiNi 0.5 Mn 1.5 O 4 bulk material (synthesized according to a solid-state route described elsewhere), 16 10% conductive carbon, and 20% polyvinylidene fluoride as a binder in N-methylpyrrolidone and stirred overnight. Further details on the characterization of the active materials can be found in the Supporting Information in Figures S1−S3.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Correlation between Chemical and Morphological Heterogeneities in LiNi_0.5Mn_1.5O₄ Spinel Composite Electrodes for Lithium-Ion Batteries Determined by Micro-X-ray Fluorescence Analysis

et al. 2015

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The high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel is a promising material for high-energy battery applications, despite problems of capacity fade. This is due in part to transition metal leaching that produces chemical and morphological inhomogeneities. Using fast micro-X-ray fluorescence spectroscopy to scan the sample at medium spatial resolution (500 nm) over millimeter ranges, effects of cycling rate and state-of-charge on the elemental distribution (Ni and Mn) for LiNi 0.5 Mn 1.5 O 4 /carbon composite electrodes in LNMO/Li cells are visualized. Charge distribution is imaged by mapping the Ni oxidation state by acquisition of a stack of elemental maps in the vicinity of the Ni K edge. Our results show significant effects on morphology and elemental distribution, such as formation of elemental hot-spots and material erosion, becoming more pronounced at higher cycling rates. In nickel hot-spots, we observed hampered oxidation of nickel during charging. ■ INTRODUCTIONThe high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel is a promising material for high-energy battery applications because of its high operation potential of ∼4.7 V versus Li + /Li 0 . However, this high potential lies outside the thermodynamic window of stability for conventional electrolyte solutions used in Li-ion batteries, and therefore presents a critical hurdle toward application. 1 As one result, oxidation of the electrolyte by the active material produces passivating products, causing reduced cycle life and capacity fade of the material. 2−4 Furthermore, Mn-containing phases such as the LiMn 2 O 4 spinel and also the LiNi 0.5 Mn 1.5 O 4 spinel are known to be susceptible to leaching of Mn 2+ and Ni 2+ to the electrolyte, 5 possibly as a consequence of the parasitic reactions with the electrolyte, 6,7 thereby causing elemental inhomogeneities in the electrodes. Formation of hydrofluoric acid, caused by trace amounts of water in the electrolyte, is regarded as one origin for this cathode corrosion. 8,9 The effect on capacity fade is especially pronounced in LNMO/graphite full cells, because of the detrimental contribution of the deposited 3d metals on the anode impacting the solid-electrolyte-interphase (SEI) growth on its surface. 2,10−13 The interplay between Ni and Mn cations leads to complex ordering effects, formation of secondary rock-salt structures, variable Mn 3+ content, and oxygen vacancies that all significantly influence electrochemical performance and are determined by the synthesis conditions. 6,14−16 Detailed investigations of the composition−structure relationship in LNMO spinel showed systematic deviations from the theoretical stoichiometry involving an excess of Mn. To compensate for the formation of excess Mn 3+ , formation of a rock-salt-type structure with a lower Mn/Ni ratio was observed. 17 A systematic study by Choi and Manthiram 5 on manganese dissolution into the electrolyte revealed a correlation with the Mn oxidation state, with samples containing initially more Mn 3+ being prone to the disproportionation reaction...

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“…

{LiFePO}_{4}

(LFP) is a promising cathode material because of its low environmental footprint, intrinsic safety, high power capabilities, and potential for low cost . However, low electrical conductivity and slow

{Li}^{+}

ion diffusion limit LFP applications . Reducing the particle size (comminution) down to submicron and nano‐sized particles improves both characteristics.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound assisted wet stirred media mill of high concentration LiFePO₄ and catalysts

Rostamizadeh

Mameri

et al. 2018

Can J Chem Eng

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Wet media mills grind solids to the nanometric size and the performance of the mills depends on solids loading, particle morphology, surfactant concentration, and material characteristics. As the particle size decreases, they tend to form clusters that reduce the grinding efficiency. Ultrasound deagglomerates these clusters thereby increasing efficiency but, surprisingly, it can operate at higher solids concentrations. We processed suspensions of LiFePO 4 (LFP) with a yttria stabilized zirconia media with a size from 0.3 mm to 0.4 mm, and surfactant-to-LFP mass ratio 0.008. The combined method ground the particle size from 35 m down to 0.2 m in 90 min with a throughput of 0.68 kg LFP /kg media /h. We also tested the improved wet media milling on two catalysts: (WO 3 /TiO 2 and vanadyl pyrophosphate (VPP) precursor) to confirm the trends. We adopt a model for the steady state and repeatable micronizing process with ultrasonic assistance. According to TEM imaging the WO 3 /TiO 2 catalyst primary particles (20 nm) are much smaller than the agglomerated ones measured by laser diffraction (470 nm). VPP precursor slurry is normally an unstable suspension that is hard to mill. It formed agglomerates with recrystallized silica and VPP flocculation. The ultrasound-assisted wet milling technique produced nanometer scale particles (180 nm), which is otherwise impossible. We developed and updated the steady state micronizing process with ultrasonic assistance using a simplified population balance model. The model accounts for R 2 > 0.95 of the variance in the experimental data.

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Nanostructured and nanoporous LiFePO4 and LiNi0.5Mn1.5O4-δ as cathode materials for lithium-ion batteries

Cited by 19 publications

References 84 publications

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Correlation between Chemical and Morphological Heterogeneities in LiNi_0.5Mn_1.5O₄ Spinel Composite Electrodes for Lithium-Ion Batteries Determined by Micro-X-ray Fluorescence Analysis

Ultrasound assisted wet stirred media mill of high concentration LiFePO₄ and catalysts

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Nanostructured and nanoporous LiFePO4 and LiNi0.5Mn1.5O4-δ as cathode materials for lithium-ion batteries

Cited by 19 publications

References 84 publications

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Off-stoichiometric Li3-3V2+(PO4)3/C as cathode materials for high-performance lithium-ion batteries

Correlation between Chemical and Morphological Heterogeneities in LiNi0.5Mn1.5O4 Spinel Composite Electrodes for Lithium-Ion Batteries Determined by Micro-X-ray Fluorescence Analysis

Ultrasound assisted wet stirred media mill of high concentration LiFePO4 and catalysts

Contact Info

Product

Resources

About

Correlation between Chemical and Morphological Heterogeneities in LiNi_0.5Mn_1.5O₄ Spinel Composite Electrodes for Lithium-Ion Batteries Determined by Micro-X-ray Fluorescence Analysis

Ultrasound assisted wet stirred media mill of high concentration LiFePO₄ and catalysts