| Summary: | 碩士 === 國立臺南大學 === 綠色能源科技研究所 === 97 === Lithium ion battery is a major component for providing power in electronic equipment. Use of electrolyte additive is one of the must economic and effectivemethod for the improvement of Li-ion battery performance.
The components of electrolyte are mixing with LiPF6, EC, and chain carbonate. Many literatures reported the vinyl- & oxy- groups compounds additives as vinylene carbonate (VC) can significantly improve the cycle life and the reversible capacity for the Li-ion battery. The main function of vinylgroup is electrochemical polymerization with the material of Solid electrolyte interface (SEI) film on graphite surface during SEI film formation. The functions of oxy- groups, electron-withdrawing groups, are mainly component of SEI film and make the vinyl group more electrophilic and thus facilitate reduction.
The electrochemical behaviors of the Vinylene trithiocarbonate (VTC) as an additive in electrolyte for Li-ion battery are investigated by cyclic voltammetry, chronocoulometry, and AC impedance. Half cell test can provide the cycle life performance for optimum amount of VTC. The surface analysis of SEI films modified by VTC and VC are investigated by FTIR and, SEM, which can be distinguished by the difference of sulfur and oxygen elements. The optimum amount of VTC can provide for lithium ion battery application. Based on the results which obtain this investigation, the best compositions of SEI structure containing sulf- group can be identify. These results help us to design and synthesis the best additives for Li-ion battery in the future project.
Therefore, the arm of this work is to elucidate the influence of electrochemical properties and surface properties on SEI film of graphite by VTC and VC as additives in electrolyte for Li-ion battery.
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