【摘要】：摘要：液流電池是大規(guī)模儲(chǔ)能電池中極其重要的一部分。它具有啟動(dòng)速度快,能量效率高等特點(diǎn)。本論文工作探索了一種新型氧化還原液流電池,即鋅鐵電池。使用循環(huán)伏安法,交流阻抗法和充放電測(cè)試等方法,研究了正極電極液及電極材料的電化學(xué)性質(zhì)。 制備了以硫酸為介質(zhì)的正極鐵電解液,研究了不同鐵離子濃度及硫酸的濃度的對(duì)電解液電化學(xué)性能的影響。發(fā)現(xiàn)1.00mol/L鐵離子在0.50mol/L的硫酸中能穩(wěn)定存在30天；Fe(Ⅲ)/Fe(Ⅱ)氧化還原反應(yīng)是準(zhǔn)可逆反應(yīng),當(dāng)鐵離子的濃度為1.00mol/L,硫酸的濃度為0.50mol/L,其擴(kuò)散系數(shù)約為2.276×10-6cm2/s;電化學(xué)阻抗約為2.238Ω·cm2。以Fe(Ⅲ)/Fe(Ⅱ)正極電解液為正極與Zn(Ⅱ)、Zn為負(fù)極組成電池,當(dāng)電流密度為20mA/cm2時(shí),充電電壓在1.65-1.72V,放電電壓在1.11-1.25V,能持續(xù)穩(wěn)定充放電110個(gè)循環(huán)。當(dāng)電流密度為30mA/cm2,充電電壓在1.68-1.80V,放電電壓在1.00-1.20V,能持續(xù)穩(wěn)定充放電近30個(gè)循環(huán)。 使用聚丙烯腈石墨氈作為電池正極,并對(duì)石墨氈進(jìn)行了高溫和酸處理等改性。經(jīng)研究發(fā)現(xiàn),處理過的石墨氈,在相同電位下,其電流密度提高4mA/cm2,電極電阻減小3Ω·cm2。電池充放電數(shù)據(jù)表明,未處理的石墨氈的充電電壓范圍在1.60-1.80V,放電電壓范圍在0.90-1.12V。經(jīng)處理過的石墨氈,充電電壓減小約0.1V,放電電壓約提高0.1V。同時(shí),電極活化的時(shí)間也大大縮短。 制備了復(fù)合碳素電極,并對(duì)其進(jìn)行了電化學(xué)測(cè)試。經(jīng)研究發(fā)現(xiàn)其氧化還原反應(yīng)是準(zhǔn)可逆反應(yīng)；電化學(xué)阻抗約為3.154Ω·cm2。充放電測(cè)試表明：當(dāng)電流密度為20mA/cm2時(shí),其容量效率約為78%,當(dāng)為30mA/cm2,容量效率約為75%；當(dāng)為40mA/cm2,電池的穩(wěn)定性下降。CB-PVDF組成的復(fù)合碳素電極的電化學(xué)活性很低,氧化還原反應(yīng)的電化學(xué)阻抗約為23.54Ω-cm2；電極本身的電阻很大；當(dāng)電流密度為20mA/cm2時(shí),其充電電壓為1.75-2.5V,放電電壓為0.5-0.75V。可認(rèn)為此電極不適合用于此液流電池的正極。探索了不同質(zhì)量比的GP-PVDF對(duì)電化學(xué)性能的影響。循環(huán)伏安法表明,當(dāng)質(zhì)量比為3：2時(shí),其可逆性已趨于不變。充放電表明：當(dāng)GP-PVDF的質(zhì)量比為1：1時(shí),電極的活性激化需要的時(shí)間約6個(gè)小時(shí),隨著石墨含量的增加,激活的時(shí)間逐漸縮短。當(dāng)質(zhì)量比為7：3和4：1不在變化。其容量效率約為86%。但當(dāng)質(zhì)量比為4：1時(shí),其效率呈逐漸減小趨勢(shì)。因此,可認(rèn)為GP-PVDF的質(zhì)量比為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.
【學(xué)位授予單位】：中南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM912

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