Graphite oxide electrode study for vanadium redox flow battery

本文主要以實驗探討全釩氧化還原液流電池(Vanadium Redox Battery,VRB)電極之效率為研究重點，總共分為石墨氈電極之製程、石墨氈電極活化、單電池效率與內電阻量測三部分。首先經由高溫碳化、石墨化後製得軟性石墨氈。再利用氣相合成碳纖維法製得具奈米碳管之石墨氈；含浸酚醛樹脂法製得硬質石墨氈。藉此製得高表面積、低阻值之電極，穿透電阻可由原本0.168mΩ/cm2降低至0.054mΩ/cm2。石墨氈電極的活化是經由熱處理、酸處理、鹼處理三種方式，進而增加電極表面的官能基團與電極表面積。實驗結果顯示當電極加熱到350℃與浸泡於濃流酸溶液中2hr皆具有較好的電化學活性。單電池效率量測實驗結果得知，硬質石墨氈經過350℃的活化熱處理後，充放電效率達80%，經由本研究探索石墨氈電極製作得以應用於全釩氧化還原液流電池，也呈現出可行的功能性實證於釩電池應用。This study discussed the VRB (Vanadium Redox Battery) electrode efficiency by experiments including graphite felt electrode process, graphite felt electrode activation, single cell efficiency and internal resistance measurement. This study obtained soft graphite felt through high temperature carbonization and graphitization. It then employed the vapor grown carbon fibers method to prepare graphite felt with carbon nanotubes. The impregnation phenolic resin method was used to prepare rigid graphite felt. The large surface area and low resistance electrode obtained by the process can reduce the through-plane resistance from 0.168mΩ/cm2 to 0.054mΩ/cm2. The graphite felt electrode activation can be realized by heat treatment, acid treatment and alkali treatment to increase electrode surface functional groups and electrode surface area. The experimental results showed that, when the electrode is heated up to 350℃ and is soaked in acid solution with high concentration for two hours, good electrochemical activation can be realized. The experimental results on the single cell efficiency measurement showed that the charge and discharge efficiency of the battery after the activation heat processing at 350℃ of the rigid graphite felt can be up to 80%. The proposed graphite felt electrode can be applied in VRB. This study demonstrated the feasible and functional empirical results of vanadium battery applications.摘要..............................................................................................................................Ⅰ Abstract........................................................................................................................Ⅱ 目錄..............................................................................................................................Ⅲ 圖目錄.........................................................................................................................ⅤI 表目錄......................................................................................................................ⅤⅢ 第一章 緒論..................................................................................................................1 1.1前言....................................................................................................................1 1.2研究動機與目的................................................................................................2 第二章 全釩氧化還原液流電池原理及文獻回顧......................................................5 2.1各體系之液流電池介紹....................................................................................5 2.1.1多硫化納-溴化鈉液流電池......................................................................6 2.1.2全釩液流電池...........................................................................................6 2.1.3溴-釩液流電池..........................................................................................7 2.1.4鐵-鉻陰/陽離子隔離膜液流電池............................................................7 2.1.5鋅-銫液流電池..........................................................................................7 2.2全釩氧化還原液流電池原理簡介....................................................................8 2.2.1二次電池與液流電池的比較.................................................................11 2.3電極材料的介紹..............................................................................................13 2.3.1金屬類電極.............................................................................................13 2.3.2碳素類電極.............................................................................................14 2.3.3一體化複合電極.....................................................................................15 2.4全釩氧化還原液流電池文獻探討..................................................................17 第三章 實驗方法與步驟............................................................................................23 3.1實驗流程及耗材設備......................................................................................23 3.2石墨氈電極製程.............................................................................................26 3.3石墨氈電極改質..............................................................................................27 3.3.1氣相合成碳纖維法.................................................................................28 3.3.2含浸酚醛樹脂法…….............................................................................29 3.4電極活化處理................................................................................................30 3.5電極量測分析................................................................................................31 3.5.1掃描式電子顯微鏡FE-SEM...................................................................31 3.5.2小角度X光繞射儀SA-XRD..................................................................31 3.5.3穿透電阻量測.........................................................................................31 3.6單電池測試....................................................................................................32 3.6.1單電池設計.............................................................................................32 3.6.2電解液製備.............................................................................................34 3.6.3質子交換膜活化處理.............................................................................36 3.6.4充放電步驟與方法.................................................................................37 第四章 結果與討論....................................................................................................39 4.1石墨氈電極改質............................................................................................39 4.1.1氣相沉積碳纖維法..................................................................................40 4.1.2含浸酚醛樹脂法......................................................................................41 4.2電極活化處理................................................................................................41 4.3石墨氈電極穿透電阻....................................................................................44 4.4單電池測試....................................................................................................45 4.4.1電解液.....................................................................................................45 4.4.2電解液流速.............................................................................................48 4.4.3軟性石墨氈充放電效率.........................................................................49 4.4.4硬質石墨氈充放電效率.........................................................................50 4.4.5多次循環效率測試.................................................................................51 第五章 結論與未來展望............................................................................................53 5.1結論..................................................................................................................53 5.2未來展望..........................................................................................................54 參考文獻......................................................................................................................5