Impedance of Lithium Electrodes in a Propylene Carbonate Electrolyte

Succinic anhydride (SA) is an useful electrolyte additive for high voltage cathodes but has also a negative impact on graphite (Gr) or Li anodes. For this reason, the Li/electrolyte and Gr/electrolyte interfaces were investigated at 20 • C and 45 • C using half or symmetrical cells. When SA is added at 1% by weight to the electrolyte (alkylcarbonate mixture + LiPF 6 ), an increase in the Li/Li cell impedance at 20 • C occurs owing to the formation of a resistive solid electrolyte interphase (SEI), composed of an inorganic inner layer and an organic outer layer, whereas at 45 • C or in absence of SA, the interphase is more inorganic in nature. The reversible capacity of graphite, cycled in Gr/Li half-cells in the presence of SA, is very low at 20 • C but almost ten times larger at 45 • C. Cycling symmetrical Gr/Gr cells at 45 • C indicates that Gr capacity is lower in the presence of SA in connection with the presence of an organic and polymer rich SEI. GC-MS analysis of the electrolyte after cycling shows that ethylene glycol bis-(alkylcarbonate) derivatives disappear when SA is present, owing to the ability of SA to react with lithium alkoxides to yield oligopolyester. Lithium ion batteries (LIBs) are a reliable way to store electric energy, with high gravimetric and volumetric energy density, which allows their application in nomad systems including electric and/or hybrid vehicles. However, electric vehicles range is unsuitable for most of the consumers and, therefore, energy density should be improved. In the past twenty years, many researches have been performed on electrode materials and electrolytes with the aim to enhance battery performance. Use of 5V class positive electrodes (cathodes) is a convenient way to increase LIBs energy density. It explains the development of promising "high voltage" materials like Li 3 V 2 (PO 4 ) 3 , 1 Li 2 CoPO 4 F 2 or the LiNi 0.5 Mn 1.5 O 4 (LNMO) 3 spinel. Nevertheless, the use of new cathodes operating at high voltage leads to the degradation of the battery electrolyte, usually based on a mixture of cyclic and linear alkylcarbonates containing LiPF 6 as salt and functional additives. Unfortunately, standard electrolytes are oxidized on 5 V cathodes and this significantly limits the battery cycling life. From the first cycles, electrolyte components degrade forming by-products, which in turn, can interact with electrodes surface. As an example, a passive layer is formed on graphite (Gr)/electrolyte interface at the first charge. This layer, known as the Solid Electrolyte Interphase (SEI), has a strong impact on the LIBs performances. Electrolyte formulation influences the chemical nature and structure of the SEI. With the aim to improve SEI quality and stability, SEI-forming additives like vinylene carbonate (VC) are generally added to the electrolyte in low amount (less than 5% by weight). These additives are designed to generate a protective passive layer on the active material surface preventing continuous electrolyte decomposition reactions.Whereas additives can be ...

Section: Resultsmentioning

confidence: 99%

“…A low frequency tail on the Nyquist plot is usually seen when lithium is in contact with alkylcarbonate solvents 11,13 or even polymer membranes (Li-PEO-LiTFSI/Li system).…”

Section: Resultsmentioning

confidence: 99%

Reactivity of Succinic Anhydride at Lithium and Graphite Electrodes

Charton

Santos-Peña

Biller

et al. 2017

“…The structure and composition of the surface film on lithium in carbonate-based electrolytes have been extensively investigated. 19,30,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] The electrochemical reduction of five organic carbonates -EC, PC, DEC, DMC and VCwere studied with the use of cyclic voltammetry at a gold electrode in THF/LiClO 4 supporting electrolyte. 52 The reduction potentials of all the carbonates were above 1 V (vs. Li/Li + ), with E VC being the most positive.…”

Section: Chemical Composition and Properties Of The Sei On Inert Subsmentioning

confidence: 99%

“…However, the charge-transfer resistance associated with these semicircles is significantly higher in the case of the Na-anode cell than for the Li-anode cell and indicate a significantly less resistive SEI in the latter. In the sodium-based system, including the use of a hard carbon electrode, the initial impedance plot shows a large high-frequency loop, which extends over more than 30 .cm 2 . This grows with time and reaches more than 50 .cm 2 after 120 hours, while the shape of the loop becomes less like a semicircle.…”

Section: Future Systemsmentioning

confidence: 99%

Review—SEI: Past, Present and Future

Peled

Menkin

2017

1,560

1,474

The Solid-Electrolyte-Interphase (SEI) model for non-aqueous alkali-metal batteries constitutes a paradigm change in the understanding of lithium batteries and has thus enabled the development of safer, durable, higher-power and lower-cost lithium batteries for portable and EV applications. Prior to the publication of the SEI model (1979), researchers used the Butler-Volmer equation, in which a direct electron transfer from the electrode to lithium cations in the solution is assumed. The SEI model proved that this is a mistaken concept and that, in practice, the transfer of electrons from the electrode to the solution in a lithium battery, must be prevented, since it will result in fast self-discharge of the active materials and poor battery performance. This model provides [E. Peled, in "Lithium Batteries," J.P. Gabano (ed), Academic Press, (1983), E. Peled, J. Electrochem. Soc., 126, 2047Soc., 126, (1979.] new equations for: electrode kinetics (i o and b), anode corrosion, SEI resistivity and growth rate and irreversible capacity loss of lithium-ion batteries. This model became a cornerstone in the science and technology of lithium batteries. This paper reviews the past, present and the future of SEI batteries. The PastPrior to the publication of the SEI model (1979), 1,4 researchers used the Butler-Volmer equation, in which direct electron transfer from the electrode to lithium cations in the solution is assumed. It was generally assumed that the rate-determining step (RDS) is the transfer of electrons from the metal to the cations in the solution. Researchers found that the lithium anode is covered by a passivating layer which interferes with the deposition/dissolution process of the anode. Brummer and Newman 2,3 concluded that a passivating anode can offer only a limited cycle life and in order to obtain a deep-discharge high-cycle-life secondary battery, the lithium anode must be free of a passivating layer and kinetically stable with respect to the electrolyte. The SEI model proved that this is a mistaken concept and that, in practice, the transfer of electrons from the electrode to the solution in a lithium battery, except when forming a SEI, must be prevented. The Present, Lithium-Metal and Lithium-Ion BatteriesIntroduction.-It is now generally accepted that the solidelectrolyte interphase (SEI) is essentially for the existence and successful operation of lithium-and sodium-battery systems, as primary and secondary power sources. 4 In 1979, it was proposed by Peled,

“…On the other hand, the solvation structure of Li-ion and formation of ion pairs in electrolyte solutions composed of G4 and a TFSI were similar to that of organic electrolyte. 18 On the other hand, in the case of [Li(G4)][TFSI] before the formation of SEI on the graphite electrode, the potential flat domain in the low potential region was not observed. Moreover, the charge-discharge action showed big irreversible capacity to the first cycle.…”

mentioning

confidence: 96%

Effect of SEI Component on Graphite Electrode Performance for Li-Ion Battery Using Ionic Liquid Electrolyte

Nakatani

Kishida

Nakagawa

2018

In this study, we investigated the role of solid electrolyte interface (SEI) With the growing global interest in environmental and energy issues, the importance of storage technology is increasing. Lithium ion batteries (LIBs) are one of the most promising electric storage devices, since they have feature as high energy density, long cycle lives and low self-discharge rate etc.1-3 Therefore, LIBs are used as a power source for portable device, electric vehicle and so on. However, the number of fire accident caused by LIBs is not negligible. These are largely attributed to organic electrolyte. A large number of organic electrolyte have a safety hazard: flammability, volatility. [3][4][5] In order to improve the safety of LIBs, the safer alternative electrolytes that replace the organic electrolytes are strongly required.Recent years, ionic liquids are generating a lot of attention in terms of safety. Ionic liquids excel in thermal stability, non-volatility and wide liquid region.6-11 Some of these characteristics are suitable for use over the wide temperature region. Furthermore, they also have electrochemical abilities: high ion-conducting, wide electrochemical window. Ion conduction is closely related to battery performance: internal resistance, discharged capacity and energy density. Using ionic liquid of wide electrochemical window, various electrode materials can contribute to LIBs. From the above of characteristics, ionic liquids have possibilities as a novel electrolyte instead of organic electrolyte for LIBs and some of these were reported that can intercalate Li-ions into graphite electrode. Some ionic liquids containing bis (fluorosulfonyl) 12-17 However, since FSI anion is inferior in thermal stability to bis(trifluoromethylsulfonyl)imide (TFSI) anion, ionic liquid containing TFSI anion is considered to be effective in improving the safety of LIBs. Many ionic liquids containing TFSI anion cannot occur intercalation reaction of Li-ions into the graphite layers. Because they cannot form solid electrolyte interface (SEI) on the graphite electrode. This causes decomposition of the ionic liquid to proceed on graphite electrode.In typical LIB using organic electrolyte, solvated Li-ions are decomposed and deposited as SEI on graphite electrode surface in the first cycle. SEI promote desolvation of Li-ions from solvated Li-ions and enables intercalation of Li-ions into graphite layers. Moreover, the SEI also have a role of suppressing the decomposition of the electrolyte after the second cycle. Therefore, the SEI is indispensable for stable operation of LIBs. [18][19][20][21][22][23][24][25][26] In this study, we tried the appearance of charge/discharge capacity in ionic liquids using graphite negative electrode. Generally, it is difficult to occur reversible charge and discharge reaction in ionic liquids using graphite negative electrode. ExperimentalSpherical natural graphite CGB-10 (Nippon Graphite Industries, Ltd.) was used as the electrode. Cellulose (TF4050) was used as the separator. Lithium metal (L...