The study of the anodic stability of alkyl carbonate solutions by in situ FTIR spectroscopy, EQCM, NMR and MS

Moshkovich, M.; Cojocaru, Miriam; Gottlieb, Hugo E.; Aurbach, Doron

doi:10.1016/s0022-0728(00)00457-5

Cited by 232 publications

(201 citation statements)

References 13 publications

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“…Further, the generated R • radicals might attack EC molecules leading to polymers, which could eventually passivate the electrode surface. 31 The reaction paths 2 and 3 are less likely to be favored by the presence of water, since their leaving groups do not offer any -CH 2 + groups for the nucleophilic attack of water.…”

Section: Discussionmentioning

confidence: 99%

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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Carbon coatings on cathode materials with low electrical conductivity like phospho-olivines LiMPO 4 (M = 3d-transition metal) are known to improve their performance in Li-ion batteries. However, at high potentials and in the presence of water, the stability of carbon coatings on high-voltage materials (e.g., LiCoPO 4 ) may be limited due to the anodic oxidation of carbon. In this work, we describe the synthesis of LiFePO 4 (LFP) with an isotopically labeled 13 C carbon coating (characterized by Raman spectroscopy, electrical conductivity, and charge/discharge rate capability tests) as a model compound to study the anodic stability of carbon coated cathode materials in ethylene carbonate-based electrolytes. We characterize the degradation of the 13 C carbon coating by On-line Electrochemical Mass Spectrometry (OEMS) through the 13 CO 2 and 13 CO signals in order to differentiate the anodic oxidation of the coating ( 13 C) from the oxidation of electrolyte, conductive carbon, and binder (all 12 C) in the electrode. The oxidation of the carbon coating takes place at potentials ≥ 4.75 V for electrolyte without H 2 O (< 20 ppm) and ≥ 4.5 V for electrolyte with 4000 ppm H 2 O, and it is strongly enhanced for H 2 O-containing electrolyte. The extent of carbon coating oxidation over 100 h at 4.8 and 5.0 V vs. Li/Li + (25 • C) is projected on the basis of our OEMS data, suggesting that carbon coatings have insufficient stability at such high cathodic potentials. Furthermore, our results prove the in situ formation of H 2 O during the anodic decomposition of ethylene carbonate-containing electrolyte. The H 2 O formation is monitored via the detection of gaseous POF 3 , which is formed from the reaction of Li-ion batteries are extensively investigated as energy storage devices for electric vehicles (EVs) due to their high energy density and reasonable life time.1 In order to make EVs competitive with gasoline or diesel cars, and to eventually reduce CO 2 emissions by the electrification of personal mobility, many fundamental challenges still need to be overcome. In contrast to NMC and other layered oxides, phospho-olivines like LFP and LCP suffer from very poor electrical conductivity which limits their rate capability, i.e., their performance at high charge/discharge rates. 7 In the case of LFP, its poor electrical conductivity can be overcome by using small primary particles (0.1-0.5 μm) in combination with an electrically conductive very thin carbon coating (thickness 1-2 nm) 8 applied to the primary particles using different kinds of precursors.7,9 While uncoated LFP samples either show very poor rate capability or low capacity at rates as low as 0.1 C, 10-12 Lou et al. 13 showed that carbon coated LFP can reach 116 mAh/g LFP at high rates of 10 C (theoretical capacity: 170 mAh/g LFP ).3 Even when the current is increased to 30 C, the discharge capacity can still reach 75 mAh/g LFP , and in the 100 th cycle the capacity loss is only 2.3%. 14 presented a carbon coated LFP which is able to reach discharge capacities of 1...

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Section: Discussionmentioning

confidence: 99%

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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“…Electrolyte decomposition products such as LiF, 28 acetone, 19 aldehydes, 31 carbon dioxide, 20,21,31 organic radicals, 27 and unidentified polymer, polyether, and carboxylic acid species 22,[24][25][26]34 have been detected either in gas form or on the surfaces of Li x Mn 2 O 4 , as well as on Li x CoO 2 and noble metal electrodes set at voltages comparable to those of Li x Mn 2 O 4 . The salt used in the electrolyte strongly affects the surface film composition and properties.…”

Section: -18mentioning

confidence: 98%

First-Principles Modeling of the Initial Stages of Organic Solvent Decomposition on Li_xMn₂O₄(100) Surfaces

2012

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Density functional theory and ab initio molecular dynamics simulations are applied to investigate the initial steps of ethylene carbonate (EC) decomposition on spinel Li 0.6 Mn 2 O 4 (100) surfaces. EC is a key component of the electrolyte used in lithium ion batteries. We predict an slightly exothermic EC bond breaking event on this oxide facet, which facilitates subsequent EC oxidation and proton transfer to the oxide surface. Both the proton and the partially decomposed EC fragment weaken the Mn-O ionic bonding network. Implications for interfacial film made of decomposed electrolyte on cathode surfaces, and Li x Mn 2 O 4 dissolution during power cycling, are discussed. keywords: lithium ion batteries; lithium manganate; ethylene carbonate; density functional theory; ab initio molecule dynamics; computational electrochemistry 1

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“…The SEI film is a thin passivating layer that is initially formed, on both anode and cathode surfaces, from the reduction of the electrolyte during the first charging/discharging cycles. [2][3][4][5][6][7][8][9] It consists of a mixture of inorganic and organic products, such as LiF, Li 2 O and LiCO 3 , and (CH 2 OCO 2 Li) 2 , ROCO 2 Li and ROLi, where R is an organic group such as CH 2 , CH 3 , CH 2 CH 2 , CH 2 CH 3 , CH 2 CH 2 CH 3 that depends on the electrolyte solvent.10-24 Proposed structure models suggest that a dense layer of inorganic products is found near the electrode (inner layer) followed by a porous organic layer near the electrolyte/SEI interface (outer layer). [19][20][21] In carbon anodes, the SEI layer prevents further decomposition of the electrolyte by hindering electron transport from the electrode to the electrolyte, and by blocking the travel of solvent molecules to the active surface of the anode, where they can react with lithium ions and electrons.…”

mentioning

confidence: 99%

Ion Diffusivity through the Solid Electrolyte Interphase in Lithium-Ion Batteries

Benitez

Seminario

2017

J. Electrochem. Soc.

109

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Understanding the transport properties of the solid electrolyte interphase (SEI) is a critical piece in the development of lithium ion batteries (LIB) with better performance. We studied the lithium ion diffusivity in the main components of the SEI found in LIB with silicon anodes and performed classical molecular dynamics (MD) simulations on lithium fluoride (LiF), lithium oxide (Li 2 O) and lithium carbonate (Li 2 CO 3 ) in order to provide insights and to calculate the diffusion coefficients of Li-ions at temperatures in the range of 250 K to 400 K, which is within the LIB operating temperature range. We find a slight increase in the diffusivity as the temperature increases and since diffusion is noticeable at high temperatures, Li-ion diffusion in the range of 1300 K to 1800 K was also studied and the diffusion mechanisms involved in each SEI compound were analyzed. We observed that the predominant mechanisms of Li-ion diffusion included vacancy assisted and knock-off diffusion in LiF, direct exchange in Li 2 O, and vacancy and knock-off in Li 2 CO 3 . Moreover, we also evaluated the effect of applied electric fields in the diffusion of Li-ions at room temperature. The continuous demand for smart phones, tablets and other mobile devices has enormously promoted the improvement of Li-ion batteries. Moreover, volatile oil prices, pollution and climate change concerns have further increased the need for energy storage devices for renewable energies and electric vehicles. The latter applications require batteries with even higher energy density, better cycle life, better power performance, lower cost and improved safety.1 Therefore, improving and increasing the fundamental scientific knowledge of lithium ion batteries is essential for their continual advancement.A key component in lithium ion batteries is the solid electrolyte interphase (SEI) film. The SEI film is a thin passivating layer that is initially formed, on both anode and cathode surfaces, from the reduction of the electrolyte during the first charging/discharging cycles. [2][3][4][5][6][7][8][9] It consists of a mixture of inorganic and organic products, such as LiF, Li 2 O and LiCO 3 , and (CH 2 OCO 2 Li) 2 , ROCO 2 Li and ROLi, where R is an organic group such as CH 2 , CH 3 , CH 2 CH 2 , CH 2 CH 3 , CH 2 CH 2 CH 3 that depends on the electrolyte solvent.10-24 Proposed structure models suggest that a dense layer of inorganic products is found near the electrode (inner layer) followed by a porous organic layer near the electrolyte/SEI interface (outer layer). [19][20][21] In carbon anodes, the SEI layer prevents further decomposition of the electrolyte by hindering electron transport from the electrode to the electrolyte, and by blocking the travel of solvent molecules to the active surface of the anode, where they can react with lithium ions and electrons. 25 In silicon anodes, i.e., the huge volume expansion of the anode creates cracks in the SEI layer and generates new surfaces which are freshly exposed to the electrolyte. 26 In both carbon and si...

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The study of the anodic stability of alkyl carbonate solutions by in situ FTIR spectroscopy, EQCM, NMR and MS

Cited by 232 publications

References 13 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

First-Principles Modeling of the Initial Stages of Organic Solvent Decomposition on Li_xMn₂O₄(100) Surfaces

Ion Diffusivity through the Solid Electrolyte Interphase in Lithium-Ion Batteries

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The study of the anodic stability of alkyl carbonate solutions by in situ FTIR spectroscopy, EQCM, NMR and MS

Cited by 232 publications

References 13 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

First-Principles Modeling of the Initial Stages of Organic Solvent Decomposition on LixMn2O4(100) Surfaces

Ion Diffusivity through the Solid Electrolyte Interphase in Lithium-Ion Batteries

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Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

First-Principles Modeling of the Initial Stages of Organic Solvent Decomposition on Li_xMn₂O₄(100) Surfaces