应用于液流电池的铁电解液及电极材料研究
发布时间：2018-07-18 11:34
【摘要】：摘要：液流电池是大规模储能电池中极其重要的一部分。它具有启动速度快,能量效率高等特点。本论文工作探索了一种新型氧化还原液流电池,即锌铁电池。使用循环伏安法,交流阻抗法和充放电测试等方法,研究了正极电极液及电极材料的电化学性质。 制备了以硫酸为介质的正极铁电解液,研究了不同铁离子浓度及硫酸的浓度的对电解液电化学性能的影响。发现1.00mol/L铁离子在0.50mol/L的硫酸中能稳定存在30天；Fe(Ⅲ)/Fe(Ⅱ)氧化还原反应是准可逆反应,当铁离子的浓度为1.00mol/L,硫酸的浓度为0.50mol/L,其扩散系数约为2.276×10-6cm2/s;电化学阻抗约为2.238Ω·cm2。以Fe(Ⅲ)/Fe(Ⅱ)正极电解液为正极与Zn(Ⅱ)、Zn为负极组成电池,当电流密度为20mA/cm2时,充电电压在1.65-1.72V,放电电压在1.11-1.25V,能持续稳定充放电110个循环。当电流密度为30mA/cm2,充电电压在1.68-1.80V,放电电压在1.00-1.20V,能持续稳定充放电近30个循环。 使用聚丙烯腈石墨毡作为电池正极,并对石墨毡进行了高温和酸处理等改性。经研究发现,处理过的石墨毡,在相同电位下,其电流密度提高4mA/cm2,电极电阻减小3Ω·cm2。电池充放电数据表明,未处理的石墨毡的充电电压范围在1.60-1.80V,放电电压范围在0.90-1.12V。经处理过的石墨毡,充电电压减小约0.1V,放电电压约提高0.1V。同时,电极活化的时间也大大缩短。 制备了复合碳素电极,并对其进行了电化学测试。经研究发现其氧化还原反应是准可逆反应；电化学阻抗约为3.154Ω·cm2。充放电测试表明：当电流密度为20mA/cm2时,其容量效率约为78%,当为30mA/cm2,容量效率约为75%；当为40mA/cm2,电池的稳定性下降。CB-PVDF组成的复合碳素电极的电化学活性很低,氧化还原反应的电化学阻抗约为23.54Ω-cm2；电极本身的电阻很大；当电流密度为20mA/cm2时,其充电电压为1.75-2.5V,放电电压为0.5-0.75V。可认为此电极不适合用于此液流电池的正极。探索了不同质量比的GP-PVDF对电化学性能的影响。循环伏安法表明,当质量比为3：2时,其可逆性已趋于不变。充放电表明：当GP-PVDF的质量比为1：1时,电极的活性激化需要的时间约6个小时,随着石墨含量的增加,激活的时间逐渐缩短。当质量比为7：3和4：1不在变化。其容量效率约为86%。但当质量比为4：1时,其效率呈逐渐减小趋势。因此,可认为GP-PVDF的质量比为7：3是最佳的。
[Abstract]:Abstract: liquid flow battery is a very important part of large-scale energy storage battery. It has the characteristics of fast starting speed and high energy efficiency. In this paper, a new type of redox flow battery, that is, zinc iron battery, is explored. Using cyclic voltammetry, AC impedance method and charge discharge test, the positive electrode liquid and electrode are studied. The electrochemical properties of the material.
The positive iron electrolyte with sulfuric acid as medium was prepared. The influence of the concentration of iron ions and sulphuric acid on the electrochemical performance of the electrolyte was studied. It was found that the 1.00mol/L iron ions were stable for 30 days in the sulfuric acid of 0.50mol/L; the Fe (III) /Fe (II) redox reaction was a quasi reversible reaction, when the concentration of iron ions was 1.00mol/L, sulfur. The concentration of acid is 0.50mol/L, the diffusion coefficient is about 2.276 x 10-6cm2/s, the electrochemical impedance is about 2.238 Omega cm2., and Fe (III) /Fe (II) /Fe (II) cathode electrolyte is positive and Zn (II), Zn is a negative electrode. When the current density is 20mA/cm2, the charging voltage is 1.65-1.72V and the discharge voltage is in 1.11-1.25V, and the charge and discharge can be kept stable and discharge 110 cycles. The flow density is 30mA/cm2, the charging voltage is 1.68-1.80V, the discharge voltage is 1.00-1.20V, and it can maintain stable charge and discharge for nearly 30 cycles.
Polyacrylonitrile graphite felt was used as the positive electrode, and the graphite felt was modified by high temperature and acid treatment. It was found that the treated graphite felt at the same potential increased the current density by 4mA/cm2, and the electrode resistance decreased by 3 Omega cm2. battery charging and discharging data, indicating that the charge voltage range of untreated graphite felt was in 1.60-1.80V. The electrical voltage ranges from 0.90-1.12V. to treated graphite felt. The charging voltage is reduced by about 0.1V, and the discharge voltage is increased by 0.1V.. Meanwhile, the time of electrode activation is also greatly reduced.
The composite carbon electrode was prepared and the electrochemical test was carried out. It was found that the redox reaction was a quasi reversible reaction, and the electrochemical impedance was about 3.154 Omega cm2. charge discharge test showed that when the current density was 20mA/cm2, the capacity efficiency was about 78%, when 30mA/cm2, the capacity efficiency was about 75%; when 40mA/cm2, the battery was stable. The electrochemical activity of the composite carbon electrode composed of a qualitative decrease of.CB-PVDF is very low. The electrochemical impedance of the redox reaction is about 23.54 Omega -cm2, and the electrode itself has a large resistance. When the current density is 20mA/cm2, the charge voltage is 1.75-2.5V and the discharge voltage is 0.5-0.75V.. The electrode is not suitable for the positive pole of the liquid flow battery. The effect of GP-PVDF on the electrochemical performance of different mass ratio was explored. The cyclic voltammetry showed that when the mass ratio was 3:2, the reversibility of the electrode tended to change. The charge and discharge showed that when the mass ratio of GP-PVDF was 1:1, the time needed for the active activation of the electrode was about 6 hours, and the activation time was gradually shortened with the increase of graphite content. The mass ratio of 7:3 and 4:1 is not changed. Its capacity efficiency is about 86%., but when the mass ratio is 4:1, its efficiency decreases gradually. Therefore, it is considered that the mass ratio of GP-PVDF to 7:3 is the best.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912
本文编号：2131779
[Abstract]:Abstract: liquid flow battery is a very important part of large-scale energy storage battery. It has the characteristics of fast starting speed and high energy efficiency. In this paper, a new type of redox flow battery, that is, zinc iron battery, is explored. Using cyclic voltammetry, AC impedance method and charge discharge test, the positive electrode liquid and electrode are studied. The electrochemical properties of the material.
The positive iron electrolyte with sulfuric acid as medium was prepared. The influence of the concentration of iron ions and sulphuric acid on the electrochemical performance of the electrolyte was studied. It was found that the 1.00mol/L iron ions were stable for 30 days in the sulfuric acid of 0.50mol/L; the Fe (III) /Fe (II) redox reaction was a quasi reversible reaction, when the concentration of iron ions was 1.00mol/L, sulfur. The concentration of acid is 0.50mol/L, the diffusion coefficient is about 2.276 x 10-6cm2/s, the electrochemical impedance is about 2.238 Omega cm2., and Fe (III) /Fe (II) /Fe (II) cathode electrolyte is positive and Zn (II), Zn is a negative electrode. When the current density is 20mA/cm2, the charging voltage is 1.65-1.72V and the discharge voltage is in 1.11-1.25V, and the charge and discharge can be kept stable and discharge 110 cycles. The flow density is 30mA/cm2, the charging voltage is 1.68-1.80V, the discharge voltage is 1.00-1.20V, and it can maintain stable charge and discharge for nearly 30 cycles.
Polyacrylonitrile graphite felt was used as the positive electrode, and the graphite felt was modified by high temperature and acid treatment. It was found that the treated graphite felt at the same potential increased the current density by 4mA/cm2, and the electrode resistance decreased by 3 Omega cm2. battery charging and discharging data, indicating that the charge voltage range of untreated graphite felt was in 1.60-1.80V. The electrical voltage ranges from 0.90-1.12V. to treated graphite felt. The charging voltage is reduced by about 0.1V, and the discharge voltage is increased by 0.1V.. Meanwhile, the time of electrode activation is also greatly reduced.
The composite carbon electrode was prepared and the electrochemical test was carried out. It was found that the redox reaction was a quasi reversible reaction, and the electrochemical impedance was about 3.154 Omega cm2. charge discharge test showed that when the current density was 20mA/cm2, the capacity efficiency was about 78%, when 30mA/cm2, the capacity efficiency was about 75%; when 40mA/cm2, the battery was stable. The electrochemical activity of the composite carbon electrode composed of a qualitative decrease of.CB-PVDF is very low. The electrochemical impedance of the redox reaction is about 23.54 Omega -cm2, and the electrode itself has a large resistance. When the current density is 20mA/cm2, the charge voltage is 1.75-2.5V and the discharge voltage is 0.5-0.75V.. The electrode is not suitable for the positive pole of the liquid flow battery. The effect of GP-PVDF on the electrochemical performance of different mass ratio was explored. The cyclic voltammetry showed that when the mass ratio was 3:2, the reversibility of the electrode tended to change. The charge and discharge showed that when the mass ratio of GP-PVDF was 1:1, the time needed for the active activation of the electrode was about 6 hours, and the activation time was gradually shortened with the increase of graphite content. The mass ratio of 7:3 and 4:1 is not changed. Its capacity efficiency is about 86%., but when the mass ratio is 4:1, its efficiency decreases gradually. Therefore, it is considered that the mass ratio of GP-PVDF to 7:3 is the best.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912
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