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

Abstract

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...

Development, retainment, and assessment of the graphite-electrolyte interphase in Li-ion batteries regarding the functionality of SEI-forming additives

“…X-ray photoelectron spectroscopy (XPS) as a non-destructive and surface-sensitive method of analysis has been used to investigate SEI composition and its contribution to Li + ion intercalation ( Nakatani et al., 2018 ). XPS could detect which elements are present on the surface and reveal the nature of chemical bonds between them; thus, it has been widely used to diagnose the decomposition products of the carbonate electrolytes, especially with differentiating C-C, C-O, and C=O bonds by C 1s/O 1s spectra ( Malmgren et al., 2013 ; Zhao et al., 2020a ).…”

“…X-ray diffraction technique (XRD) has been the other X-ray analysis applied to study the structure of the SEI layer and track the effect of the electrolyte additives in the formation process ( Lee et al., 2004 ; Li et al., 2013c ; Nakatani et al., 2018 ). Given the fact that electrolyte additives would react at the cathodic side as well, XRD has been exploited to monitor the structural changes of the cathode as an effect of additive application ( Li et al., 2013a ).…”

Crown Ether Functionalized Conductive Carbon for High-Voltage Spinel LiMn1.5Ni0.5O4/Graphite Cell

“…The graphite anode of the LMN–AB/graphite cell has a rough and nonuniform surface compared to that of the LMN–AB–B 15 C 5 /graphite cell. This could be related to more important electrolyte decomposition on the graphite surface of the former . The concentration of selected elements of the graphite anode following 1, 10, and 170 cycles is presented in Figures a,b and S8.…”

Growth Mechanism of Micro/Nano Metal Dendrites and Cumulative Strategies for Countering Its Impacts in Metal Ion Batteries: A Review

“…It can be inferred from Figure 23i,ii that the charge transfer resistance (Rct) of the anode is related to two activation processes: (i) desolvation of Li + ions and (ii) its transition through the SEI layer. The cation transport number (total electrons carried in an electrolyte by cations) must approach one in order to eliminate the effects of the polarization concentration [215,216]. In alkali metal batteries, the equivalent volume of SEI material should be higher than the metal anode's volume in order to achieve better protection [217].…”