Ionic conductivity of substituted Li2SO4 phases

Kimura, Naoji; Greenblatt, Martha

doi:10.1016/0025-5408(84)90243-5

Cited by 22 publications

(7 citation statements)

References 12 publications

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“…This latter case is the fundamental reason that diffusion in Li 2 CO 3 is energetically predisposed to the knock-off mechanism. Actually, the knock-off diffusion mechanism is quite general for other ionic structures and has been observed in compounds with isolated polyhedral anions or layered tetrahedral networks such as LiBO 2 , Li 2 SO 4 , Li 3 PO 4 , Li 4 SiO 4 , LiF, and Li 2 O, as proposed on the basis of DFT results while lacking experimental confirmation.…”

Section: Resultsmentioning

confidence: 99%

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

Lü²,

et al. 2012

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The mechanism of Li(+) transport through the solid electrolyte interphase (SEI), a passivating film on electrode surfaces, has never been clearly elucidated despite its overwhelming importance to Li-ion battery operation and lifetime. The present paper develops a multiscale theoretical methodology to reveal the mechanism of Li(+) transport in a SEI film. The methodology incorporates the boundary conditions of the first direct diffusion measurements on a model SEI consisting of porous (outer) organic and dense (inner) inorganic layers (similar to typical SEI films). New experimental evidence confirms that the inner layer in the ∼20 nm thick model SEI is primarily crystalline Li(2)CO(3). Using density functional theory, we first determined that the dominant diffusion carrier in Li(2)CO(3) below the voltage range of SEI formation is excess interstitial Li(+). This diffuses via a knock-off mechanism to maintain higher O-coordination, rather than direct-hopping through empty spaces in the Li(2)CO(3) lattice. Mesoscale diffusion equations were then formulated upon a new two-layer/two-mechanism model: pore diffusion in the outer layer and knock-off diffusion in the inner layer. This diffusion model predicted the unusual isotope ratio (6)Li(+)/(7)Li(+) profile measured by TOF-SIMS, which increases from the SEI/electrolyte surface and peaks at a depth of 5 nm, and then gradually decreases within the dense layer. With no fitting parameters, our approach is applicable to model general transport properties, such as ionic conductivity, for SEI films on the surface of other electrodes, from the atomic scale to the mesoscale, as well as aging phenomenon.

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Section: Resultsmentioning

confidence: 99%

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

Lü²,

et al. 2012

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“…optimization of preparative parameters (9); ii.) substitution of the aliovalent impurities (10)(11)(12), i.e., an approach based on the classical charge compensation (doping) mechanism; iii.) trapping of high-temperature, highly conducting phases at room temperature (13); iv.)…”

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confidence: 99%

On the Insertion of 7Li2 O : 3 B 2 O 3 Glass into the Polycrystalline 6Li2 SO 4 : 4Li2 CO 3 Composite System

Singh

Bhoga

1990

J. Electrochem. Soc.

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The ionic conductivity of 7Li20:3B203 glass inserted in 6Li2SO4:4Li2CO3 eutectic has been studied as a function of temperature and frequency. With such insertion, a prominent increase in the conductivity (by two orders of magnitude at low temperature) has been observed. The results have been explained in the light of dispersed phase theory, and supported by microstructural evidence. These results could provide a new approach for the development of polycrystalline solid electrolytes.

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“…S6) comprising Li-sulfate, Lisulfite, and TM-sulfates as established by XPS studies. We suggest that nano-sized Li 2 SO 4 surface species may act as Li-ion conductive domains 57,58 enhancing thus the lithium-ion transport through the near-surface region into the bulk of the oxide. We propose that the higher discharge capacity of SO 2 -treated HE-NCM during the first activation cycle, as well as its enhanced capacity during cycling, might be explained by the "non-electrochemical" activation of the Li 2 MnO 3 domains (as discussed below) and by the enhanced the lithium-ion transport through the near-surface region into the oxide bulk.…”

Section: Resultsmentioning

confidence: 93%

Enhancement of Electrochemical Performance of Lithium and Manganese-Rich Cathode Materials via Thermal Treatment with SO₂

Sclar

Sicklinger

Erickson

et al. 2020

J. Electrochem. Soc.

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In this study, we present a novel surface modification approach via SO 2 gas treatment at 200 °C-400 °C to enhance the electrochemical performance of Li and Mn-rich cathode materials 0.35Li 2 MnO 3 •0.65LiNi 0.35 Mn 0.45 Co 0.20 O 2 (HE-NCM) for advanced lithium-ion batteries. It was established by X-ray photoelectron spectroscopy that the SO 2 treatment leads to the formation of surface sulfates and sulfites on the material, while the bulk remains unaffected, as confirmed by X-ray and electron diffraction studies. Based on the results obtained, we proposed possible mechanisms of the SO 2 thermal treatment that include partial reduction of manganese (however, we could not find any substantial evidence for it in the XPS data) and oxidation of sulfur. The electrochemical performance was evaluated by testing the materials as cathodes in coin-type half-cells with metallic lithium anodes at 25 °C and 30 °C. The main findings are as follows: the SO 2 -treated materials demonstrate ∼10% higher capacity at all C-rates and lower the voltage hysteresis during prolonged cycling compared to the untreated samples. The proposed approach to modify the surface of HE-NCM materials by SO 2 treatment is demonstrated to be a promising method to enhance the electrochemical performance of these cathodes.

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Ionic conductivity of substituted Li2SO4 phases

Cited by 22 publications

References 12 publications

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

On the Insertion of 7Li2 O : 3 B 2 O 3 Glass into the Polycrystalline 6Li2 SO 4 : 4Li2 CO 3 Composite System

Enhancement of Electrochemical Performance of Lithium and Manganese-Rich Cathode Materials via Thermal Treatment with SO₂

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Ionic conductivity of substituted Li2SO4 phases

Cited by 22 publications

References 12 publications

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

On the Insertion of 7Li2 O : 3 B 2 O 3 Glass into the Polycrystalline 6Li2 SO 4 : 4Li2 CO 3 Composite System

Enhancement of Electrochemical Performance of Lithium and Manganese-Rich Cathode Materials via Thermal Treatment with SO2

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Enhancement of Electrochemical Performance of Lithium and Manganese-Rich Cathode Materials via Thermal Treatment with SO₂