前驅(qū)體中硫化物對超級電容器活性炭電極電容性能的影響研究
發(fā)布時間：2018-08-13 13:30
【摘要】：隨著科技和社會的迅速發(fā)展,人們對高性能電源的需求量越來越大。超級電容器作為一種新型的儲能元件成為了世界各國新能源領(lǐng)域的研究熱點(diǎn)之一。目前,高性能電極材料的開發(fā)是超級電容器主要的研究目標(biāo)。活性炭由于具有超高的比表面積、高電導(dǎo)率、原料豐富、價格低廉及較好的電化學(xué)穩(wěn)定性等特點(diǎn),一直是制造超級電容器電極的首選材料。礦物質(zhì)及其衍生物(瀝青、石油焦、煤等)資源豐富、價格低廉,已成為制備活性炭的重要原料。 本文以瀝青(Pitch)、石油焦(PC)為原料,通過外加有機(jī)硫化物DBT、無機(jī)硫化物黃鐵礦FeS2合成含硫模擬前驅(qū)體(ASCPs),采用KOH化學(xué)活化法制備超級電容器活性炭(AC)電極材料。ASCPs實(shí)現(xiàn)了單因素系統(tǒng)考察前驅(qū)體中硫化物的種類及含量對活性炭結(jié)構(gòu)及其電化學(xué)性能影響規(guī)律的研究。采用X-射線衍射(XRD)、元素分析、X-射線光電子能譜(xPS)、x-射線近邊吸收光譜(XANES)、液相離子色譜等研究測試方法對硫化物的含量及形態(tài),活性炭表面官能團(tuán)等進(jìn)行表征分析；掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)、低溫氮?dú)馕絻x等測試手段對樣品的孔形貌及孔結(jié)構(gòu)進(jìn)行表征；通過循環(huán)伏安(CV)、恒流充放電(GCD)、交流阻抗(EIS)等電化學(xué)方法測試了材料的電化學(xué)性能。初步探索了前驅(qū)體中的硫化物對AC的孔結(jié)構(gòu)性能及其電極材料電容性能的影響規(guī)律及影響機(jī)理。主要研究內(nèi)容及結(jié)論如下： (1)系統(tǒng)研究了前驅(qū)體中有機(jī)硫化物二苯并噻吩(DBT)對活性炭結(jié)構(gòu)及其電極電化學(xué)性能的影響規(guī)律與機(jī)理。結(jié)果表明,在AC的制備過程中,隨著ASCPs中DBT含量逐漸增大,DBT與KOH反應(yīng)生成的K2SO4的量逐漸增大,因此實(shí)際用于活化拓孔的KOH量逐漸減少,即實(shí)際的堿炭比KOH/Pitch逐漸下降,從而使得AC樣品的比表面積、孔容、平均孔徑等呈現(xiàn)出逐漸降低的趨勢。電化學(xué)測試表明,隨著ASCPs中DBT含量逐漸增大,AC電極的儲電性能、倍率特性、循環(huán)性能等呈現(xiàn)出逐漸降低的趨勢。然而,無論ASCPs中DBT含量如何,活性炭中均未發(fā)現(xiàn)有殘余硫化物。此外,通過適量增加活化劑KOH的量,補(bǔ)償活化反應(yīng)過程中因DBT反應(yīng)消耗KOH的量,可以完全消除因DBT的存在對活性炭孔結(jié)構(gòu)及電容性能造成的負(fù)面影響。對于實(shí)際應(yīng)用而言,含DBT的含硫礦物質(zhì)前驅(qū)體也可以作為制備高性能AC潛在的廉價前驅(qū)體。 (2)系統(tǒng)研究了前驅(qū)體中典型無機(jī)硫化物黃鐵礦(FeS2)對活性炭結(jié)構(gòu)及其電極電化學(xué)性能的影響規(guī)律與機(jī)理。結(jié)果表明,在活化過程中,FeS2與活化劑KOH發(fā)生化學(xué)反應(yīng)生成Fe3O4、K2SO4、K2SO3、K2S2O3、K2S和硫醚C-S-C,并由此導(dǎo)致實(shí)際堿/碳比降低,即活化拓孔用KOH量減少,AC活化不足,表現(xiàn)為AC的孔容積、比表面積等參數(shù)的降低,進(jìn)而使得AC電極材料的比電容及倍率特性等呈現(xiàn)出逐漸降低的趨勢。此外,FeS2與KOH反應(yīng)的副產(chǎn)物Fe304難以通過傳統(tǒng)的水洗法從活化產(chǎn)物中去除,其會作為雜質(zhì)存在于AC中,從而導(dǎo)致AC電極儲電性能下降。非常有趣的是,S-XANES及XPS分析結(jié)果均顯示,前驅(qū)體中FeS2會導(dǎo)致AC表面生成有機(jī)硫醚類C-S-C含硫官能團(tuán),這表明經(jīng)過復(fù)雜的KOH活化反應(yīng),前驅(qū)體中一部分無機(jī)類FeS2會轉(zhuǎn)化為有機(jī)含硫官能團(tuán),并成為活性炭自身的有機(jī)組成部分。雖然C-S-C官能團(tuán)能以贗電容的形式在一定程度上提高AC電極材料的比電容,但總體而言,FeS2對AC電容性能產(chǎn)生的負(fù)面影響超過C-S-C含硫官能團(tuán)產(chǎn)生的促進(jìn)作用。同時,與有機(jī)硫化物DBT相比,無機(jī)硫化物FeS2對AC孔結(jié)構(gòu)性能及其電極材料的電化學(xué)性能產(chǎn)生的負(fù)面影響難以通過簡單的增大活化劑KOH的用量加以減小或消除。因此,對于實(shí)際應(yīng)用而言,應(yīng)當(dāng)嚴(yán)格控制超級電容器用活性炭礦物質(zhì)前驅(qū)體中FeS2的含量,盡可能降低其含量及其帶來的負(fù)面影響。
[Abstract]:With the rapid development of science, technology and society, the demand for high-performance power supply is increasing. As a new type of energy storage element, supercapacitor has become one of the hotspots in the field of new energy all over the world. High specific surface area, high conductivity, abundant raw materials, low price and good electrochemical stability have been the preferred materials for the manufacture of supercapacitor electrodes.
In this paper, sulfur-containing analog precursor (ASCPs) was synthesized from pitch and petroleum coke (PC) by adding organic sulfide DBT and inorganic sulfide pyrite FeS2. The electrode material of activated carbon (AC) for supercapacitor was prepared by KOH chemical activation method. The effect of sulfide type and content in precursor on activated carbon was investigated by single factor system with ASCPs. The content and morphology of sulfides and the surface functional groups of activated carbon were characterized by X-ray diffraction (XRD), elemental analysis, X-ray photoelectron spectroscopy (XPS), X-ray near-edge absorption spectroscopy (XANES), liquid chromatography, scanning electron microscopy (SEM), and so on. The pore morphology and pore structure of the samples were characterized by electron microscopy (TEM) and nitrogen adsorption apparatus at low temperature. The electrochemical properties of the samples were tested by cyclic voltammetry (CV), constant current charge-discharge (GCD) and alternating current impedance spectroscopy (EIS). The main contents and conclusions are as follows:
(1) The effects of DBT on the structure and electrochemical properties of activated carbon were studied systematically. The results showed that the amount of K2SO4 produced by the reaction of DBT with KOH increased gradually with the increase of DBT content in ASCPs during the preparation of AC, so the amount of KOH used to activate the rubbing holes increased gradually. The specific surface area, pore volume and average pore size of AC sample decrease gradually with the decrease of the actual alkali-carbon ratio KOH/Pitch. Electrochemical tests show that the storage performance, ratio characteristics and cycling performance of AC electrode decrease gradually with the increase of DBT content in ASCPs. In addition, by increasing the amount of activator KOH and compensating the amount of KOH consumed by DBT reaction, the negative effects of DBT on the pore structure and capacitance properties of activated carbon can be completely eliminated. Material precursors can also be used as potential low-cost precursors for the preparation of high-performance AC.
(2) The effects of typical inorganic sulfide pyrite (FeS2) in precursor on the structure and electrochemical performance of activated carbon were studied systematically. The results showed that during activation, FeS2 reacted with activator KOH to form Fe3O4, K2SO4, K2SO3, K2S2O3, K2S and thioether C-S-C, which resulted in the decrease of the actual alkali/carbon ratio, i.e., the activation. In addition, Fe304, a by-product of the reaction between FeS2 and KOH, is difficult to be removed from the activated products by traditional water washing method and will be stored as impurities. Interestingly, both S-XANES and XPS analysis showed that FeS2 in the precursor could induce the formation of C-S-C sulfur-containing functional groups on the surface of AC, suggesting that a part of inorganic FeS2 in the precursor could be converted into organic sulfur-containing functional groups by complex KOH activation reaction. Although C-S-C functional groups can improve the specific capacitance of AC electrode materials to some extent in the form of pseudo-capacitance, the negative effects of FeS2 on AC capacitance are more than those of C-S-C sulfur functional groups. It is difficult to reduce or eliminate the negative effects of pore structure and electrochemical properties of electrode materials by simply increasing the amount of activator KOH. Therefore, for practical application, the content of FeS2 in the precursor of activated carbon minerals for supercapacitors should be strictly controlled to minimize its content and its negative effects. Influence.
【學(xué)位授予單位】：揚(yáng)州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：O646;TM53
本文編號：2181139
[Abstract]:With the rapid development of science, technology and society, the demand for high-performance power supply is increasing. As a new type of energy storage element, supercapacitor has become one of the hotspots in the field of new energy all over the world. High specific surface area, high conductivity, abundant raw materials, low price and good electrochemical stability have been the preferred materials for the manufacture of supercapacitor electrodes.
In this paper, sulfur-containing analog precursor (ASCPs) was synthesized from pitch and petroleum coke (PC) by adding organic sulfide DBT and inorganic sulfide pyrite FeS2. The electrode material of activated carbon (AC) for supercapacitor was prepared by KOH chemical activation method. The effect of sulfide type and content in precursor on activated carbon was investigated by single factor system with ASCPs. The content and morphology of sulfides and the surface functional groups of activated carbon were characterized by X-ray diffraction (XRD), elemental analysis, X-ray photoelectron spectroscopy (XPS), X-ray near-edge absorption spectroscopy (XANES), liquid chromatography, scanning electron microscopy (SEM), and so on. The pore morphology and pore structure of the samples were characterized by electron microscopy (TEM) and nitrogen adsorption apparatus at low temperature. The electrochemical properties of the samples were tested by cyclic voltammetry (CV), constant current charge-discharge (GCD) and alternating current impedance spectroscopy (EIS). The main contents and conclusions are as follows:
(1) The effects of DBT on the structure and electrochemical properties of activated carbon were studied systematically. The results showed that the amount of K2SO4 produced by the reaction of DBT with KOH increased gradually with the increase of DBT content in ASCPs during the preparation of AC, so the amount of KOH used to activate the rubbing holes increased gradually. The specific surface area, pore volume and average pore size of AC sample decrease gradually with the decrease of the actual alkali-carbon ratio KOH/Pitch. Electrochemical tests show that the storage performance, ratio characteristics and cycling performance of AC electrode decrease gradually with the increase of DBT content in ASCPs. In addition, by increasing the amount of activator KOH and compensating the amount of KOH consumed by DBT reaction, the negative effects of DBT on the pore structure and capacitance properties of activated carbon can be completely eliminated. Material precursors can also be used as potential low-cost precursors for the preparation of high-performance AC.
(2) The effects of typical inorganic sulfide pyrite (FeS2) in precursor on the structure and electrochemical performance of activated carbon were studied systematically. The results showed that during activation, FeS2 reacted with activator KOH to form Fe3O4, K2SO4, K2SO3, K2S2O3, K2S and thioether C-S-C, which resulted in the decrease of the actual alkali/carbon ratio, i.e., the activation. In addition, Fe304, a by-product of the reaction between FeS2 and KOH, is difficult to be removed from the activated products by traditional water washing method and will be stored as impurities. Interestingly, both S-XANES and XPS analysis showed that FeS2 in the precursor could induce the formation of C-S-C sulfur-containing functional groups on the surface of AC, suggesting that a part of inorganic FeS2 in the precursor could be converted into organic sulfur-containing functional groups by complex KOH activation reaction. Although C-S-C functional groups can improve the specific capacitance of AC electrode materials to some extent in the form of pseudo-capacitance, the negative effects of FeS2 on AC capacitance are more than those of C-S-C sulfur functional groups. It is difficult to reduce or eliminate the negative effects of pore structure and electrochemical properties of electrode materials by simply increasing the amount of activator KOH. Therefore, for practical application, the content of FeS2 in the precursor of activated carbon minerals for supercapacitors should be strictly controlled to minimize its content and its negative effects. Influence.
【學(xué)位授予單位】：揚(yáng)州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：O646;TM53
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