本文關(guān)鍵詞：新型釩電池電解液穩(wěn)定性和電化學(xué)性能研究　出處：《北京化工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 釩電池 新型電解液 熱穩(wěn)定性 電化學(xué)性能

【摘要】：本文旨在提高正極電解液中V5+的熱穩(wěn)定性和電化學(xué)性能,將H2SO4與HCl組成的混酸作為正極電解液,通過總酸濃度及鹽酸比例的調(diào)節(jié),研究其對于V5+熱穩(wěn)定性及參與電極反應(yīng)歷程的影響。此外,還進(jìn)一步探討了添加鹽酸的負(fù)極電解液中V2+的穩(wěn)定性和電化學(xué)性能變化,主要研究內(nèi)容如下：首先,電解制備2M V5+正極電解液,在30℃至60℃,監(jiān)測不同混酸體系水浴1Oh后V5+濃度變化,進(jìn)而考察H2SO4濃度與HCl濃度對于V5+熱穩(wěn)定性的影響。研究表明,HCl的加入可以提高V5+高溫穩(wěn)定性,這可能是由于Cl-可以與五價釩氧離子形成多核的釩氧氯粒子,這種粒子在高溫?fù)碛懈叩姆�(wěn)定性,可以抑制V205沉淀的生成。并且在40℃至50℃時,這種抑制沉淀生成的效果尤為明顯。但是Cl-這種提高V5+穩(wěn)定性必須建立在一定濃度的H2SO4體系中,即2M V5+必須在2.0M以上的H2SO4中才可以長時間穩(wěn)定存在。此外,V5+高溫?zé)岱�(wěn)定性并非隨HCl濃度的提升越高越好,當(dāng)電解液中氫離子濃度接近10M,V5+高溫?zé)岱�(wěn)定性隨HCl濃度增加而降低,這可能是由于體系中總酸度過高,自由移動的H20減少,體系中多核的釩氧氯粒子容易重新締合在一起生成沉淀或者經(jīng)過碰撞失去Cl原子而又轉(zhuǎn)變成較易形成沉淀的單核釩氧離子而進(jìn)一步形成沉淀。其次,利用CV、線性極化區(qū)掃描、恒電流階躍、EIS四種電化學(xué)測試方法,主要從電機反應(yīng)歷程中電化學(xué)步驟和液相傳質(zhì)步驟兩個角度,探討H2SO4含量與HCl含量對于混酸體系中活性物質(zhì)反應(yīng)動力學(xué)參數(shù)的影響。研究表明,由5M、4M及2.5+3、3+2.5、3+3、2+3、2+4、2+6體系觀察發(fā)現(xiàn),隨著HCl濃度的增加,電極反應(yīng)中電化學(xué)極化電阻Re呈先降低后增大再減小又增大的趨勢,這可能是由于HCl的添加,體系中生成了新的單核釩氧氯粒子,這種粒子擁有較好的電活性所致；隨著鹽酸比例的提高,當(dāng)H2SO4濃度降低到2.5M以下時,受H2SO4濃度的影響,釩氧離子活性降低,因此Re得以增大,但是隨著Cl-的增加,溶液中單核釩氧氯離子相互配合形成大量多核釩氧氯粒子,這種粒子的結(jié)構(gòu)使其擁有更高的電活性,因此Re再降低,但是隨著Cl-進(jìn)一步增加,體系中過剩的Cl-特性吸附在電極表面,降低電極表面活性點,使電極反應(yīng)電荷轉(zhuǎn)移的難度增大,因此Re出現(xiàn)升高。Rc先減小是由于,隨著H2804濃度降低,體系黏度減小,液相傳質(zhì)變得更為容易；而后又升高是由于多核的釩氧氯粒子的半徑較大,在雙電層中傳遞到電極表面更為困難所致。最后,利用上述四種電化學(xué)研究方法研究了HCl的添加對于V2+參與負(fù)極半反應(yīng)歷程的影響,研究發(fā)現(xiàn)HCl的加入雖然可以有效的提高了半反應(yīng)的i0,降低了電化學(xué)步驟的阻力大小,但是液相傳質(zhì)步驟阻力明顯增大,因其為電極反應(yīng)的速度控制步驟,因此體系總極化電阻Rp增加,不利于整個體系電極反應(yīng)的進(jìn)行。此外,通過電位滴定的方法監(jiān)測了電解完成10h內(nèi)負(fù)極電解液中V2+濃度的變化,研究表明,HCl的添加不利于V2+保持穩(wěn)定溶解,因此,H2SO4與HCl組成的混酸不適合作為負(fù)極電解液的支持電解質(zhì)。
[Abstract]:The purpose of this paper is to improve the thermal stability and electrochemical performance of V5+ in positive electrolyte. The mixed acid composed of H2SO4 and HCl is used as the positive electrolyte. The effects of total acid concentration and hydrochloric acid proportion on the thermal stability of V5+ and the participation in electrode reaction process are studied. In addition, further discusses the change of stability and electrochemical performance of cathode electrolyte hydrochloric acid is added in V2+, the main research contents are as follows: firstly, the electrolytic preparation of 2M V5+ cathode electrolyte, at 30 degrees centigrade to 60 degrees centigrade, monitoring the concentration change of V5+ mixed acid system 1Oh water bath after different, and the effects of H2SO4 concentration and HCl concentration on the thermal stability of V5+. The research shows that the addition of HCl can improve the stability of V5+ at high temperature, which may be due to vanadium oxychloride particles Cl- can form polynuclear and pentavalent vanadium oxygen ions, the particles have higher stability at high temperature, V205 can restrain the generation of precipitation. And the effect of this inhibition is particularly obvious at 40 to 50 degrees C. However, the stability of Cl- to improve V5+ must be established in a certain concentration of H2SO4 system, that is, 2M V5+ must be stable in the H2SO4 above 2.0M for a long time. In addition, V5+ thermal stability is not increased with the concentration of HCl is good, when the concentration of hydrogen ions in the electrolyte is close to 10M, V5+ thermal stability decreased with the increase of HCl concentration, which may be due to the total acidity in the system is too high, free mobile H20 reduced vanadium oxychloride particles in multi-core system easy to associate together to form precipitate or after the collision of Cl atoms and lost into the easy formation of mononuclear vanadyl ion precipitation and further the formation of precipitation. Secondly, by using CV and scanning, linear polarization current step and EIS four electrochemical test methods, mainly from two angles of motor in electrochemical reaction process steps and liquid phase mass transfer steps on H2SO4 content and HCl content for the effects of active substances mixed acid system kinetic parameters. Research shows that, by 5M, 4M and 2.5+3, 3+2.5, 3+3, 2+3, 2+4, 2+6 system was observed with the increase of HCl concentration, the electrode reaction in the electrochemical polarization resistance Re decreased first and then increased and then decreased and increased, which may be due to the addition of HCl, the system generates a new single core vanadium oxychloride particles, the particles have better electrical activity induced by hydrochloric acid; with the increase of the proportion of H2SO4, when the concentration is reduced to below 2.5M, affected by the concentration of H2SO4, reduce the activity of vanadium ions, so the Re can be increased, but with the increase of Cl- in the solution of mononuclear vanadyl chloride with each other to form a large number of multi core vanadium oxychloride particles, the particle structure so that it has higher electrical activity, so Re reduce, but with the further increase of Cl- in the system of Cl-, characteristics of the excess adsorption at the electrode surface, reducing the activity of the electrode surface, the electrode reaction power The difficulty of load transfer increased, so Re increased. The reduction of Rc first is due to the decrease of the viscosity of the system and the decrease of liquid mass transfer as the concentration of H2804 decreases, and then the increase is due to the larger radius of the multi core vanadium oxychloride particles, which is more difficult to transfer to the electrode surface in the double layer. Finally, HCl study of the effects of additives on V2+ in the negative half reaction process using the above four kinds of electrochemical methods, the study found that although the addition of HCl can effectively improve the half reaction I0, reduced the electrochemical step size of the resistance, but the steps of liquid phase mass transfer resistance increased significantly, because the speed of electrode reaction the control step, so the total polarization resistance of Rp system increases, is not conducive to the whole system of electrode reaction. In addition, the change of V2+ concentration in the negative electrolyte of 10h was monitored by potentiometric titration. The results showed that the addition of HCl was not good for V2+ to maintain stable dissolution. Therefore, the mixed acid composed of H2SO4 and HCl is not suitable for supporting electrolyte of negative electrolyte.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 田波,嚴(yán)川偉,屈慶,李華,王福會;釩電池電解液的電位滴定分析[J];電池;2003年04期

2 羅冬梅,許茜,隋智通;添加劑對釩電池電解液性質(zhì)的影響[J];電源技術(shù);2004年02期

3 劉納;郭興蓬;;添加劑改善釩電池陽極電解液穩(wěn)定性研究[J];電源技術(shù);2011年09期

，

本文編號：1339769