| The effect of SEI layer on the electrochemical impedance by LiTFSI as additive |
| کد مقاله : 1018-CNF |
| نویسندگان |
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صدیقه کیانی *1، حسین غریبی2، حمیده کاشانی3، محمد ژیانی4، سهیلا جوادیان5 1شیمی فیزیک- علوم پایه- تربیت مدرس- تهران - ایران 2انجمن 3شیمی فیزیک-تربیت مدرس- علوم پایه- تهران-ایران 4شیمی فیزیک- علوم پایه- تربیت مدرس- تهران- ایران 5انحمن |
| چکیده مقاله |
| Nowadays, lithium-ion batteries have been used as electronic devices and vehicle power supplies. In order to use lithium-ion batteries for electronic devices and vehicles, new requirements are required for electrode materials, including fast charging and discharging performance. To achieve this purpose, the internal resistance of the battery due to lithium-ion and electron transfer along the electrode must be reduced. Among several lithium-ion and electron transfer processes, lithium-ion transfer (charge) at the electrode/electrolyte boundary is a fundamental process of the charge-discharge reaction in lithium-ion batteries, however, little attention has been paid to the surface lithium ion transfer mechanism. We investigate the electrode-electrolyte interface (EEI) mechanism and the effect of the SEI layer on the kinetics of the charge transfer reaction. The results showed that the addition of LiTFSI as an additive to the electrolyte decreases the size of semicircle in middle-frequency in electrochemical impedance spectroscopy (EIS) analyses than the cell without additive (figure 1). Also, the middle-frequency component of the EIS varies with potential (figure 2), which is related to charge-transfer kinetics, indeed, the electrical conductivity of Li-ion varies through Li-ion intercalation/de-intercalation of cathode electrode [1]. On the other hand, the result of the holding test at constant potential showed that the impedance of charge transfer increase with increasing holding time, and the amount of these changes is less for the cell containing additive than the cell without additive (figure 3). In the following, the study of activation energy and its changes with increasing the number of charge and discharge cycles was considered. The amount of activation energy is calculated in the range of charge transfer activation energy (30-60 kJ / mol) [2] where the limiting factor of solvation and de-solvation factor is lithium-ion, and this value for the cell with additive is less than the cell without additives and increases with an increasing number of cycles figure 4. We have proposed here the low-frequency semicircle should correspond to charge transfer resistance of Li-ion to/from the active particle surface, and Li-ion migration through the SEI layer. More importantly, with adding the additive to the electrolyte, the SEI thickness was decreased and then the resistance of middle-frequency semicircle was decreased. This insight should obtain a new effect for the SEI layer and kinetics of the electrochemical interfacial reaction. |
| کلیدواژه ها |
| Li-ion battery, Electrochemical impedance spectroscopy, Electrode-electrolyte interface, solid-electrolyte interface, additive |
| وضعیت: چکیده برای ارائه به صورت پوستر پذیرفته شده است |