石墨烯應用於全釩液流電池電極材料 的電化學活性之研究

Research on the electrochemical activity of Graphene based electrode materials for Vanadium redox flow battery

楊士賢(Yang, Shih Hsien)

指導教授 ： 馬振基

國立清華大學/工學院/化學工程學系/碩士(2014年)

摘要

本研究旨在比較不同化學還原法還原的石墨烯，做為釩電池電極材料，進行電極的電化學活性之探討，研究內容如下：
藉由XPS(X-ray photoelectron spectroscopy)的鑑定，瞭解不同化學
還原方法還原之石墨烯，其結構上的含氧官能基佔整個結構的比例，進而討論不同還原劑對石墨烯氧化物的還原程度之影響以及其含氧官能基和電化學活性之關聯。
藉由循環伏安法（cyclic voltammetry），探討不同化學還原法：(利用HBr、NaBH4、N2H4等不同的還原劑)還原出的石墨烯，比較其氧化還原峰的峰值差值來探討其電化學活性，研究結果證實由HBr化學還原的石墨烯電極材料（氧化還原電位差值為0.26V，另兩者分別為0.28V、0.32V）可以得知HBr化學還原的石墨烯為電化學活性最佳的釩電池電極材料。
藉由分析電化學阻抗圖譜(Electrochemical impedance
spectroscopy)，對不同化學還原劑還原出的石墨烯，進行電極材料在釩離子電解液中的電荷轉移的能力測試，比較其阻抗值及電路模擬參數Y。由於HBr還原的石墨烯的Y值最大（9.3×10-5S.s-n，另兩者分別為9.3×10-5S.s-n、1.31×10-5S.s-n），證實釩離子吸附在由HBr還原的石墨烯上的效果最佳，間接印證由HBr還原的石墨烯電化學活性最好。

關鍵字

全釩液流電池

並列摘要

This study investigated the electrochemical activities of various chemical reduced Graphenes for electrode in all-vanadium redox flow battery (VRB) .The reductants used including NaBH4,N2H4, and HBr.
The XPS analysis was utilized to analyze the element compositions of the Graphene oxide, HBr reduced Graphene, NaBH4 reduced Graphene, and N2H4 reduced Graphene. The oxygen functional groups in Graphene is related to the electrochemical activity. The correlation between oxygen functional groups and electrochemical activity in VRB was studied in detail.
The electrochemical activities of graphene prepared with various redox reactions of [VO2]+/[VO]2+ were studied by cyclic voltammetry. Results showed that HBr reduced Graphene exhibited the highest electrochemical activity ( the smallest peak potential separation is 0.26V, 0.28V and 0.32V for NaBH4 reduced Graphene and N2H4 reduced Graphene,respectively.)due to the balance between electroactivity and electrical conductivity of the HBr reduced Graphene.

The EIS results show that the Y value of HBr reduced Graphene(9.3×10-5S.s-n) is higher than other graphenes respectively, 2.57×10-5S.s-n and 1.31×10-5 S.s-n for NaBH4 and N2H4 reduced graphene , respectively, implying that Vanadium ions adsorbed on the HBr reduced graphene electrode surface are easier than other graphenes.The easier the Vanadium ions adsorbed on the electrode , the higher the electrochemical activity. Consequently, HBr reduced graphene eletrode shows the highest electrochemical activity among various chemical reduced Graphenes.

並列關鍵字

Vanadium redox flow battery

參考文獻

[1] R. M. Dell;, D. A. Rand. J. J. Power Sources 2001, 100, 2.

[10] Sukang Bae, ‘’Roll-to-roll production of 30-inch graphene films for transparent electrodes’’, Nature Nanotechnolog, 2010,5,574

[11]X.Li,“Highly conducting graphene sheets and Langmuir–Blodgett films ,Nature Nanotechnology, 2008,3,538.

[13] H.-M. Ju, S.-H. Huh, S.-H. Choi, and L.-L. Hong, ‘‘Structures of thermally and chemically reduced graphene’’, Materials Letters, 2010, 64, 357-360.

[15] B. C. Brodie. ‘‘On the Atomic Weight of Graphite’’, Philos.Trans. R.Soc. London,1859, 14, 249–259.