SDS作为正极电解液添加剂对钒电池性能的影响

第40卷第1期兰州理工大学学报Vol. 40 No. 12014年2月.Journal of Lanzhou University of TechnologyFeb. 2014文章编号: 1673-5196(2014)01 0010-05SDS作为正极电解液添加剂对钒电池性能的影响俞伟元，高波，路文江，汤富领，张庆堂(兰州理工大学甘肃省有色金属新材料重点实验室，甘肃兰州730050)摘要:为优化钒电池正极电解液的性能，以十二烷基磺酸钠(SDS)作为钒电池正极电解液添加剂，研究不同质量分数的SDS对钒电池正极电解液的运动粘度、电导率、热稳定性以及电化学性能的影响.结果表明:正极电解液的运动粘度随添加剂质量分数的增大而逐步增大,而导电率随SDS质量分数的增加先增大至3%处的最大值372 mS●cm- 1 后再减小;SDS可以延缓Vs+离子在高温下的沉淀速度,SDS质量分数为3%时,Vs+离子的热稳定性最好;扫速为50 mV.s 1下循环伏安测试表明,含添加剂w(SDS)=3%的电解液氧化峰和还原峰电流最大,分别为163. 8、142. 2 mA,电化学性能最佳;以w(SDS)=3%的电解液作为钒电池的正板电解液,电流密度为20 mA. cm-1下50次充放电循环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优越于空白电池.关键词:钒电池;十二垸基磺酸钠;运动粘度;电导率;热稳定性;电化学活性中图分类号: TF821文献标识码: 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当今,世界化石能源日益衰竭以及化石能源的单、循环寿命长以及维护费用低等优势,最近一些年广泛使用所引起的大气污染、全球变暖等问题已经受到了广泛关注14. VRFB是分别采用V2+/ V+严重影响到人们的生存,这使得风能、太阳能地热和V+/Vs+氧化还原电对作为电池的负极和正极能等可再生的清洁能源开发与存储技术研发迫在眉电解液,电池的容量和输出功率都决定于电解液的睫.全钒液流电池(VRFB)具有安全环保、结构简体积以及中国煤化工在硫酸溶液中溶解度较低HcNMH差，使得VRFBHM心心出差收稿日期: 2013-04-08作者简介:俞伟元(1973-),男,甘肃兰州人,教授.的能量密度难以超过25 W●h. kg-1[67],这极大地第1期俞伟元等:SDS作为正极电解液添加剂对钒电池性能的影响限制了VRFB更广泛的应用.充放电测试在CT2001A-10V/10A型电池测试仪在硫酸溶液中,Vs+是以水合离子[VOz(H2(LAND).上进行,采用静态单电池.电极为石墨毡，O)3]+存在的,这种结构在温度高于40 C时会先质隔膜为Nafion117阳离子交换膜.充放电电压为0.7子化然后脱水缩合形成V2O,沉淀8.针对如何提~1.7 V,充放电电流密度为20 mA●cm-'.高V5+的热稳定性,近年来已经有了很多报道.提高2结果与讨论硫酸的浓度可以很好地抑制VOt二聚缩合成V2O+和V2O3+ ,从而抑制沉淀的生成，然而V2+,2.1 SDS对V4+/ V5+电解液UV-Vis的光谱影响V+和V*+在高酸度下的溶解度却大大降低、容易图1为加了质量分数3%的SDS的V4+和V5+析晶”、十六烷基三甲基溴化铵[2]等最近,美国西电解液的UV-Vis图谱,所有测试的电解液的V+北太平洋国家实验室提出了盐酸/硫酸混酸同作为和V5+浓度均为0. 01 mol/L,硫酸浓度为3 mol/L.支持电解液,中南大学刘素琴课题组也提出用硫酸/由图可知,无论是V*+还是Vs+电解液,SDS的加人甲磺酸混酸作为支持电解液[4] ,这对提高钒离子的既没有产生 新的紫外可见吸收峰,而且最大吸收峰溶解度以及Vs+的热稳定性都取得了不错的效果.的位置也没有偏移,这表明,少量SDS的加人并没本研究中,选用了阴离子表面活性剂十二烷基有与钒离子发生反应产生新的物质[9],可以与V4+磺酸钠( sodium dodecyl sulfonate, SDS)作为钒电和Vs+离子稳定存在.池正极电解液的添加剂，研究不同含量的SDS对正2.4极电解液的电导率、粘度、热稳定性的影响,通过循2.0 [VO*电解液环伏安测试(CV)和充放电测试,分析SDS对电解.6一空 ，液电化学性能的影响.--- w(SDS)=3%1实验).8 L以V2Os为原料,5 mol/L的硫酸支持电解质电00 300 400 500 600 700 800 9解制备2 mol/L VOSO, +3 mol/L H2 SO4电解波长/nm液[5],将电解制备得到的2 mol/L VOSO, +3 mol/(a) V*L H2SO,作为钒液流电池的电解液进行充电,满充2.0 r后正极半电池中得到Vs+电解液[16].电解液钒离子.6 t浓度及价态通过国标法滴定.溶液的紫外可见光谱1.2一-空白(UV-Vis)测试在紫外可见光谱仪( lambda35,珀金i 0.8--- w(SDS)-3%埃尔默仪器有限公司)进行,比色皿为1 cm石英槽..4 t溶液的电导率采用电导率仪(雷磁DDS-11A,上海精密仪器有限公司)测定,测试之前在25 C水00 300 400 500 600 700 800 900浴中恒温10 min,电极为雷磁DJS-1D型.溶液的运(b) V+动粘度采用上海昌吉石油产品运动粘度测定仪SYD 265D测定,测试前在25 C水浴中恒温10图1 V4+和V+电解液紫外可见吸收光谱图min.每个样品平行测定3次,结果取其平均值.向Fig1 UV-vis absorption spectra of electrolyte solutionVs+离子浓度为1. 8 mol/L,硫酸浓度为3 mol/L的2.2 SDS 对电解液电导率和粘度的影响电解液中加人质量分数为0%~4%的SDS,在不同图2为2 mol/L VOSO, +3 mol/L H2 SO,电温度下水浴恒温0.5h,观察溶液中是否有沉淀生解液的空白溶液以及添加了质量分数为1%~4%成然后移取上层清液、过滤、滴定溶液中剩余Vs+SDS溶液的电导率和运动粘度的变化趋势图.由图离子的浓度11..循环伏安测试在电化学工作站可知,SDS加入后,溶液的运动粘度随其质量分数(CH1-660D,上海辰华)上进行,参比电极为饱和甘的增大而逐步增大,尤其是当质量分数达到4%时,汞电极,工作电极为石墨棒(1.0 cmX1. 0 cm),对其粘度剧增其原田县sns为名碳长链的有机钠电极为铂电极(1.0 cmX1. 0 cm) ,待测溶液V4+浓盐,其粘度远中国煤化工J,溶液的粘度度为2. 0 mol/L,硫酸浓度为3 mol/L,扫描区间为也随之增加.HcNMHG电解生成的0~1.6 V,扫速50 mV●s~1 ,扫描区间:0~1.6 V.Na+是良好的离子导电载体,所以SDS加入后,溶第1期俞伟元等:SDS作为正吸电解液添加剂对钒电池性能的影响●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放电容量/(mA.h~) .- -0.15) 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6图5全钒电池液流 电池采用添加和未添加SDS的电解电势/V液在20mA●cm-2的充放电曲线(a)不同质量分数循环伏安曲线Fig5 Charge discharge curves of vanadium redox battery0.20 「with electrolytes with and without SDS additive in-第1次循环case of current density of 20 mA●cm 20.10 |..... 第30次循环，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%的循环曲线循环次数(a)能量衰减图4质分数不同的SDS溶液的循环伏安曲线和w(SDS)=3%的溶液的第1个和第30个循环的CV曲线并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密度为20mA.cm-2,图5为其充放电曲线.对比(b)能量效率发现，含有SDS的电池的充电平台低于空白电池，图6钒液流电池采用添加了和未添加SDS的电解液在放电平台高于空白电池,并且放电容量也远高于空20 mA●cm~2的充放容量衰减及能量效率图白电池，这意味着SDS的加入优化了电池的性能.Fig6 Capacity fading and energy eficiency of vanadium--方面,SDS作为阴离子表面活性剂，被石墨毡电redox battery with eletrolytes with and without极吸附后改善了其润湿性,使得石墨毡在浸泡的过SDS additive due to charge-discharge in case of程中吸附了更多的钒离子使得电池的容量得以提current density of 20 mA●cm^ 2高;另一方面, SDS加人后提高了电极反应的可逆3结论性.图6为电池的容量衰减和能量效率图,结果显示,添加质量分数为3%的SDS的电解液平均容量以SDS为钒电池正极电解液添加剂,研究不同为91.6mA●h,空白电池平均容量为61.0mA●质量分数的SDS对钒电池正极电解液的运动粘度、h,其平均容量提高了50. 2%,而且容量保持率(85.电导率热稳定性以及电化学性能的影响.正极电解4%)也高于空白电池(62.4%).原因是充放电过程液的运动粘度随SDS质量分数的增大而逐步增大,中,电池内部温度升高,而SDS的加入很好地改善而其导电率随SDS质量分数的增大先增大再减小，了Vs+的热稳定性,拟制了V2Os的形成，容量衰减最大值372mS.cm-1出现在w(SDS)=3%时;小于空白电池.另外,由于SDS提高了电极反应的SDS改善了Vs+离子的热稳定性,SDS的质量分数可逆性，使得电池有着更好的能量效率,50次充放为3%时改善中国煤化工表明，添加质电循环的平均能量效率为83. 1%,高于空白的量分数为3%MYHCNMHG.解液电化学79. 2%.性能;以w(SDS) = 3%的电解液作为电池的正极电.兰州理工大学学报第40卷解液,50次充放电循环的平均容量比空白的提高了in vanadium redox flow batteries [J]. 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