SDS作為正極電解液添加劑對釩電池性能的影響

第40卷第1期蘭州理工大學(xué)學(xué)報Vol. 40 No. 12014年2月.Journal of Lanzhou University of TechnologyFeb. 2014文章編號: 1673-5196(2014)01 0010-05SDS作為正極電解液添加劑對釩電池性能的影響俞偉元，高波，路文江，湯富領(lǐng)，張慶堂(蘭州理工大學(xué)甘肅省有色金屬新材料重點(diǎn)實(shí)驗室，甘肅蘭州730050)摘要:為優(yōu)化釩電池正極電解液的性能，以十二烷基磺酸鈉(SDS)作為釩電池正極電解液添加劑，研究不同質(zhì)量分數的SDS對釩電池正極電解液的運動(dòng)粘度、電導率、熱穩定性以及電化學(xué)性能的影響.結果表明:正極電解液的運動(dòng)粘度隨添加劑質(zhì)量分數的增大而逐步增大,而導電率隨SDS質(zhì)量分數的增加先增大至3%處的最大值372 mS●cm- 1 后再減小;SDS可以延緩Vs+離子在高溫下的沉淀速度,SDS質(zhì)量分數為3%時(shí),Vs+離子的熱穩定性最好;掃速為50 mV.s 1下循環(huán)伏安測試表明,含添加劑w(SDS)=3%的電解液氧化峰和還原峰電流最大,分別為163. 8、142. 2 mA,電化學(xué)性能最佳;以w(SDS)=3%的電解液作為釩電池的正板電解液,電流密度為20 mA. cm-1下50次充放電循環(huán)的平均容量比空白的提高50. 2%,容量保持率和平均能量效率都優(yōu)越于空白電池.關(guān)鍵詞:釩電池;十二垸基磺酸鈉;運動(dòng)粘度;電導率;熱穩定性;電化學(xué)活性中圖分類(lèi)號: TF821文獻標識碼: AEffect of SDS as an additive of positive electrolyte onperformance of vanadium batteryYU Wei yuan, GAO Bo, LU Wen: jiang, TANG Fu-ling, ZHANG Qing -tang(State Key Laboratory of Gansu Advanced Nonferrous Metal Materials, Lanzhou Univ. of Tech,，Lanzhou 730050, China)Abstract: In order to optimize the performance of vanadium battery with positive electrolyte (sodium do-decyl sulfonate SDS) was employed as an additive to positive electrolyte to investigate the effect of SDScontent on the kinematic viscosity, conductivity, thermal stability and electrochemical performance of theelectrolyte. The result showed that kinetic viscosity was gradully increased with SDS content, while con-ductivity was increased first to the maximum value of 372 mS●cm -1 (SDS content:3%) with SDS contentand then decreased. The precipitating of Vs+ could be delayed by SDS and the Vs+ showed an optimal ther-mal stability when the SDS content was 3%. Cyclic voltammetry test showed that the electrolyte with 3%SDS possessed optimal electrochemical activity with the highest anodic peak current (163. 8 mA) and ca-thodic peak current (142.2 mA) in case of scan rate of 50 mV●s '. The average discharge capacity of thecell with positive electrolyte with 3% SDS was 50. 2% higher than the blank one, and the capacity reten-tion ratio (85. 4%) and average energy efficiency (83. 1%) were both superior to the blank one (61.0 %and 79. 2%, respectively) in case of current density of 20 mA cm-'.Key words: vanadium battery; sodium dodecyl sulfonate; kinematic viscosity; conductivity; thermal sta-bility; electrochemical activity當今,世界化石能源日益衰竭以及化石能源的單、循環(huán)壽命長(cháng)以及維護費用低等優(yōu)勢,最近一些年廣泛使用所引起的大氣污染、全球變暖等問(wèn)題已經(jīng)受到了廣泛關(guān)注14. VRFB是分別采用V2+/ V+嚴重影響到人們的生存,這使得風(fēng)能、太陽(yáng)能地熱和V+/Vs+氧化還原電對作為電池的負極和正極能等可再生的清潔能源開(kāi)發(fā)與存儲技術(shù)研發(fā)迫在眉電解液,電池的容量和輸出功率都決定于電解液的睫.全釩液流電池(VRFB)具有安全環(huán)保、結構簡(jiǎn)體積以及中國煤化工在硫酸溶液中溶解度較低HcNMH差，使得VRFBHM心心出差收稿日期: 2013-04-08作者簡(jiǎn)介:俞偉元(1973-),男,甘肅蘭州人,教授.的能量密度難以超過(guò)25 W●h. kg-1[67],這極大地第1期俞偉元等:SDS作為正極電解液添加劑對釩電池性能的影響限制了VRFB更廣泛的應用.充放電測試在CT2001A-10V/10A型電池測試儀在硫酸溶液中,Vs+是以水合離子[VOz(H2(LAND).上進(jìn)行,采用靜態(tài)單電池.電極為石墨氈，O)3]+存在的,這種結構在溫度高于40 C時(shí)會(huì )先質(zhì)隔膜為Nafion117陽(yáng)離子交換膜.充放電電壓為0.7子化然后脫水縮合形成V2O,沉淀8.針對如何提~1.7 V,充放電電流密度為20 mA●cm-'.高V5+的熱穩定性,近年來(lái)已經(jīng)有了很多報道.提高2結果與討論硫酸的濃度可以很好地抑制VOt二聚縮合成V2O+和V2O3+ ,從而抑制沉淀的生成，然而V2+,2.1 SDS對V4+/ V5+電解液UV-Vis的光譜影響V+和V*+在高酸度下的溶解度卻大大降低、容易圖1為加了質(zhì)量分數3%的SDS的V4+和V5+析晶”、十六烷基三甲基溴化銨[2]等最近,美國西電解液的UV-Vis圖譜,所有測試的電解液的V+北太平洋國家實(shí)驗室提出了鹽酸/硫酸混酸同作為和V5+濃度均為0. 01 mol/L,硫酸濃度為3 mol/L.支持電解液,中南大學(xué)劉素琴課題組也提出用硫酸/由圖可知,無(wú)論是V*+還是Vs+電解液,SDS的加人甲磺酸混酸作為支持電解液[4] ,這對提高釩離子的既沒(méi)有產(chǎn)生 新的紫外可見(jiàn)吸收峰,而且最大吸收峰溶解度以及Vs+的熱穩定性都取得了不錯的效果.的位置也沒(méi)有偏移,這表明,少量SDS的加人并沒(méi)本研究中,選用了陰離子表面活性劑十二烷基有與釩離子發(fā)生反應產(chǎn)生新的物質(zhì)[9],可以與V4+磺酸鈉( sodium dodecyl sulfonate, SDS)作為釩電和Vs+離子穩定存在.池正極電解液的添加劑，研究不同含量的SDS對正2.4極電解液的電導率、粘度、熱穩定性的影響,通過(guò)循2.0 [VO*電解液環(huán)伏安測試(CV)和充放電測試,分析SDS對電解.6一空 ，液電化學(xué)性能的影響.--- w(SDS)=3%1實(shí)驗).8 L以V2Os為原料,5 mol/L的硫酸支持電解質(zhì)電00 300 400 500 600 700 800 9解制備2 mol/L VOSO, +3 mol/L H2 SO4電解波長(cháng)/nm液[5],將電解制備得到的2 mol/L VOSO, +3 mol/(a) V*L H2SO,作為釩液流電池的電解液進(jìn)行充電,滿(mǎn)充2.0 r后正極半電池中得到Vs+電解液[16].電解液釩離子.6 t濃度及價(jià)態(tài)通過(guò)國標法滴定.溶液的紫外可見(jiàn)光譜1.2一-空白(UV-Vis)測試在紫外可見(jiàn)光譜儀( lambda35,珀金i 0.8--- w(SDS)-3%埃爾默儀器有限公司)進(jìn)行,比色皿為1 cm石英槽..4 t溶液的電導率采用電導率儀(雷磁DDS-11A,上海精密儀器有限公司)測定,測試之前在25 C水00 300 400 500 600 700 800 900浴中恒溫10 min,電極為雷磁DJS-1D型.溶液的運(b) V+動(dòng)粘度采用上海昌吉石油產(chǎn)品運動(dòng)粘度測定儀SYD 265D測定,測試前在25 C水浴中恒溫10圖1 V4+和V+電解液紫外可見(jiàn)吸收光譜圖min.每個(gè)樣品平行測定3次,結果取其平均值.向Fig1 UV-vis absorption spectra of electrolyte solutionVs+離子濃度為1. 8 mol/L,硫酸濃度為3 mol/L的2.2 SDS 對電解液電導率和粘度的影響電解液中加人質(zhì)量分數為0%~4%的SDS,在不同圖2為2 mol/L VOSO, +3 mol/L H2 SO,電溫度下水浴恒溫0.5h,觀(guān)察溶液中是否有沉淀生解液的空白溶液以及添加了質(zhì)量分數為1%~4%成然后移取上層清液、過(guò)濾、滴定溶液中剩余Vs+SDS溶液的電導率和運動(dòng)粘度的變化趨勢圖.由圖離子的濃度11..循環(huán)伏安測試在電化學(xué)工作站可知,SDS加入后,溶液的運動(dòng)粘度隨其質(zhì)量分數(CH1-660D,上海辰華)上進(jìn)行,參比電極為飽和甘的增大而逐步增大,尤其是當質(zhì)量分數達到4%時(shí),汞電極,工作電極為石墨棒(1.0 cmX1. 0 cm),對其粘度劇增其原田縣sns為名碳長(cháng)鏈的有機鈉電極為鉑電極(1.0 cmX1. 0 cm) ,待測溶液V4+濃鹽,其粘度遠中國煤化工J,溶液的粘度度為2. 0 mol/L,硫酸濃度為3 mol/L,掃描區間為也隨之增加.HcNMHG電解生成的0~1.6 V,掃速50 mV●s~1 ,掃描區間:0~1.6 V.Na+是良好的離子導電載體,所以SDS加入后,溶第1期俞偉元等:SDS作為正吸電解液添加劑對釩電池性能的影響●13●2.00.151%1.8-空白2%1.60.101.4w(SDS)= 3%0.05S 1.2-0.8-- 0.050.60102030405060708090100-0.10 t放電容量/(mA.h~) .- -0.15) 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6圖5全釩電池液流 電池采用添加和未添加SDS的電解電勢/V液在20mA●cm-2的充放電曲線(xiàn)(a)不同質(zhì)量分數循環(huán)伏安曲線(xiàn)Fig5 Charge discharge curves of vanadium redox battery0.20 「with electrolytes with and without SDS additive in-第1次循環(huán)case of current density of 20 mA●cm 20.10 |..... 第30次循環(huán)，110 rw(SDS)=3%9- 0.0; 70-0.1050-0.150.2 0.4 0.6 0.8 1.01.21.4 1.6301020340(b) w(SDS)=3%的循環(huán)曲線(xiàn)循環(huán)次數(a)能量衰減圖4質(zhì)分數不同的SDS溶液的循環(huán)伏安曲線(xiàn)和w(SDS)=3%的溶液的第1個(gè)和第30個(gè)循環(huán)的CV曲線(xiàn)并8Fig4 Cydic voltage current curves of SDS solution with脂7:various mass-fractions and 1* and 30* CV curvesof SDS solution with 3% mass-fraction6510 20 30密度為20mA.cm-2,圖5為其充放電曲線(xiàn).對比(b)能量效率發(fā)現，含有SDS的電池的充電平臺低于空白電池，圖6釩液流電池采用添加了和未添加SDS的電解液在放電平臺高于空白電池,并且放電容量也遠高于空20 mA●cm~2的充放容量衰減及能量效率圖白電池，這意味著(zhù)SDS的加入優(yōu)化了電池的性能.Fig6 Capacity fading and energy eficiency of vanadium--方面,SDS作為陰離子表面活性劑，被石墨氈電redox battery with eletrolytes with and without極吸附后改善了其潤濕性,使得石墨氈在浸泡的過(guò)SDS additive due to charge-discharge in case of程中吸附了更多的釩離子使得電池的容量得以提current density of 20 mA●cm^ 2高;另一方面, SDS加人后提高了電極反應的可逆3結論性.圖6為電池的容量衰減和能量效率圖,結果顯示,添加質(zhì)量分數為3%的SDS的電解液平均容量以SDS為釩電池正極電解液添加劑,研究不同為91.6mA●h,空白電池平均容量為61.0mA●質(zhì)量分數的SDS對釩電池正極電解液的運動(dòng)粘度、h,其平均容量提高了50. 2%,而且容量保持率(85.電導率熱穩定性以及電化學(xué)性能的影響.正極電解4%)也高于空白電池(62.4%).原因是充放電過(guò)程液的運動(dòng)粘度隨SDS質(zhì)量分數的增大而逐步增大,中,電池內部溫度升高,而SDS的加入很好地改善而其導電率隨SDS質(zhì)量分數的增大先增大再減小，了Vs+的熱穩定性,擬制了V2Os的形成，容量衰減最大值372mS.cm-1出現在w(SDS)=3%時(shí);小于空白電池.另外,由于SDS提高了電極反應的SDS改善了Vs+離子的熱穩定性,SDS的質(zhì)量分數可逆性，使得電池有著(zhù)更好的能量效率,50次充放為3%時(shí)改善中國煤化工表明，添加質(zhì)電循環(huán)的平均能量效率為83. 1%,高于空白的量分數為3%MYHCNMHG.解液電化學(xué)79. 2%.性能;以w(SDS) = 3%的電解液作為電池的正極電.蘭州理工大學(xué)學(xué)報第40卷解液,50次充放電循環(huán)的平均容量比空白的提高了in vanadium redox flow batteries [J]. 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