尖晶石型鋰空氣電池電化學(xué)催化劑的制備及其性能研究
發(fā)布時間：2018-08-31 10:00
【摘要】：當(dāng)前世界范圍內(nèi)正在經(jīng)歷新型能源體系變革,其主要內(nèi)容是將新型可再生能源取代以化石能源為基礎(chǔ)的能源體系, 實現(xiàn)由不可持續(xù)的現(xiàn)代工業(yè)文明向未來可持續(xù)的生態(tài)文明過渡,最終實現(xiàn)人類社會與地球生物圈循環(huán)規(guī)律有機(jī)融合。在所有開發(fā)的新型儲能設(shè)備中具有高理論能量密度的鋰空氣電池,引起了人們的廣泛關(guān)注。但是在鋰空氣電池運行中陰極氧氣還原反應(yīng)(ORR)動力學(xué)緩慢,會造成過電勢損失,導(dǎo)致電池的實際能量密度與理論密度相差大,循環(huán)壽命短。研究發(fā)現(xiàn)通過使用催化劑可以降低反應(yīng)活化能,減小電化學(xué)極化程度,進(jìn)而提高鋰空氣電池的實際能量密度。在現(xiàn)在已知的催化劑中貴金屬有很好的催化活性,特別是Pt類催化劑,但是由于貴金屬資源匱乏、價格昂貴,阻礙了其在電化學(xué)催化中的廣泛應(yīng)用。所以研發(fā)具有高催化活性的非貴金屬催化劑是推動鋰空氣電池商業(yè)化的關(guān)鍵。本論文選擇化學(xué)穩(wěn)定性好、價格便宜同時具有較高催化活性的尖晶石氧化物作為研究對象,使用酵母細(xì)胞和細(xì)菌纖維素作為模板和碳源,制備具有高催化活性和催化穩(wěn)定性的CoFe2O4和碳復(fù)合催化劑,另外使用Li+離子和Mn2+離子分別作為雜質(zhì)離子對NiCo2O4進(jìn)行摻雜,提高其催化活性。研究的主要內(nèi)容和取得的結(jié)果如下：(1)使用酵母細(xì)胞作碳源,通過化學(xué)沉淀法制備具有介孔結(jié)構(gòu)的CoFe2O4/Co/C復(fù)合催化劑。通過調(diào)節(jié)酵母懸浮液的濃度,制得具有不同電化學(xué)催化性能的復(fù)合產(chǎn)物。當(dāng)酵母懸浮液濃度為10 g L-1時,制得的復(fù)合產(chǎn)物CFO/Co/BC-2比表面積可以達(dá)到92.76 m2 g-1,在堿性條件下具有很好的催化活性和催化穩(wěn)定性。在ORR催化過程中,CFO/Co/BC-2的起始電位僅為-0.176 V,極限電流密度可以達(dá)到7.25 mA cm-2。在氧氣析出反應(yīng)(OER)催化過程中其氧氣析出起始電位為0.58 V,當(dāng)電壓為1 V時電流密度達(dá)到26.48 mA cm-2。當(dāng)CFO/Co/BC-2在-0.35 V下經(jīng)過86377 s連續(xù)工作后,其ORR電流密度僅降低了20.5%,在0.8 V下經(jīng)過同樣的工作時間后,其OER電流密度減小7.9%。(2)使用酵母細(xì)胞作碳源和模板,通過化學(xué)沉淀和冷凍干燥法制得直徑為1-2.5μrn的CoFe2O4/C復(fù)合微球。復(fù)合材料中的C是酵母細(xì)胞碳化后生成的N和P摻雜的無定型碳,它本身就有很好的電化學(xué)催化活性,同時CoFe2O4和C之間的耦合作用會提高催化活性,所以在堿性條件下CoFe2O4/C復(fù)合微球有很好的催化活性和催化穩(wěn)定性。在ORR催化過程中,CoFe2O4/C復(fù)合微球的氧氣還原起始電位僅為-0.14 V。在OER催化過程中,其氧氣析出起始電位為0.46 V,在電壓為0.8 V時電流密度達(dá)到17.7 mA cm-2。當(dāng)CoFe2O4/C復(fù)合微球在-0.35 V下經(jīng)過43000 s連續(xù)工作后,其ORR電流密度僅降低了15.1%,在0.8 V下經(jīng)過同樣的工作時間后,其OER電流密度減小1.4%。(3)使用酵母細(xì)胞作模板,通過簡單的兩步煅燒法制得直徑為1-2.5 μm的CoFe2O4空心微球。在ORR催化過程中,CoFe2O4空心微球的氧氣還原起始電位為-0.29 V。在OER催化過程中,CoFe2O4空心微球的氧氣析出起始電位比無規(guī)則形貌CoFe2O4小50 mV,在電壓為1 V時電流密度達(dá)到45 mA cm-2。當(dāng)CoFe2O4空心微球在-0.3 V下連續(xù)工作44000 s后,其ORR電流密度減小了16.4%,在0.8 V下經(jīng)過相同的工作時間后,其OER電流密度降低了5.6%。(4)使用細(xì)菌纖維素作模板和碳源,通過水熱法制得具有三維網(wǎng)狀結(jié)構(gòu)的CoFe2O4/C復(fù)合催化劑。在ORR催化過程中,CoFe2O4/C的氧氣還原起始電位僅為-0.09 V,極限電流密度達(dá)到5.41 mA cm-2。在OER催化過程中,其氧氣析出起始電壓為0.58 V,在電壓為1 V時電流密度達(dá)到23.02 mA cm-2。當(dāng)CoFe2O4/C復(fù)合催化劑在-0.3 V下連續(xù)工作35000 s后,其ORR電流密度減小3.7%,在0.8 V下經(jīng)過相同的工作時間后,其OER電流密度減小5.8%。(5)通過水熱法制備Li+摻雜的LixNiCo2-xO4,調(diào)節(jié)Li+離子的摻雜量,當(dāng)x=0.5時Li0.5NiCo1.5O4的ORR起始電位為-0.176 V,中間產(chǎn)物產(chǎn)率小于1%,電子轉(zhuǎn)移數(shù)在3.97-4之間。同樣通過水熱法制備Mn2+摻雜的MnxNi1-xCo2O4,當(dāng)x=0.2時Mn0.2Ni0.8Co2O4的ORR起始電位為-0.13 V,中間產(chǎn)物產(chǎn)率小于1.5%,電子轉(zhuǎn)移數(shù)在3.96-4之間。
[Abstract]:Nowadays, the world is experiencing the reform of new energy system. Its main content is to replace fossil-based energy system with new renewable energy, to realize the transition from unsustainable modern industrial civilization to sustainable ecological civilization in the future, and finally to realize the organic integration of human society and the law of the Earth's biosphere cycle. Lithium-air batteries with high theoretical energy density have attracted extensive attention in all new energy storage devices developed. However, the slow kinetics of cathode oxygen reduction reaction (ORR) in the operation of lithium-air batteries will cause overpotential loss, resulting in a large difference between the actual and theoretical energy density and short cycle life. Nowadays, noble metals have good catalytic activity, especially Pt-type catalysts. However, due to the scarcity of precious metal resources and high price, it is difficult to use them in electrochemical catalysis. Therefore, the research and development of non-noble metal catalysts with high catalytic activity is the key to promote the commercialization of lithium-air batteries. In this paper, spinel oxides with good chemical stability, low price and high catalytic activity were selected as the research object, and yeast cells and bacterial cellulose were used as templates and carbon sources to prepare lithium-air batteries. C oFe2O4 and carbon composite catalysts with high catalytic activity and catalytic stability were doped with Li+ and Mn2+ as impurity ions respectively to improve the catalytic activity of NiCo2O4. The main contents and results were as follows: (1) Mesoporous C was prepared by chemical precipitation method using yeast cells as carbon source. OFe2O4/Co/C composite catalysts. Composite products with different electrochemical catalytic properties were prepared by adjusting the concentration of yeast suspension. When the concentration of yeast suspension was 10 g L-1, the specific surface area of the composite product CFO/Co/BC-2 could reach 92.76 M 2 g-1. It had good catalytic activity and catalytic stability under alkaline conditions. In the catalytic process, the initial potential of CFO/Co/BC-2 is - 0.176 V and the limiting current density is 7.25 mA cm-2. In the process of oxygen evolution reaction (OER), the initial potential of oxygen evolution is 0.58 V, and the current density is 26.48 mA cm-2 when the voltage is 1 V. (2) C oFe2O4/C composite microspheres with a diameter of 1-2.5 microrn were prepared by chemical precipitation and freeze-drying using yeast cells as carbon source and template. The C in the composite was the amorphous carbon doped with N and P produced by carbonization of yeast cells. CoFe2O4/C composite microspheres have good catalytic activity and stability under alkaline conditions. In ORR process, the initial potential of oxygen reduction of CoFe2O4/C composite microspheres is only - 0.14 V. In OER catalytic process, the initial potential of oxygen reduction of CoFe2O4/C composite microspheres is only - 0.14 V. The ORR current density of CoFe2O4/C composite microspheres decreased by 15.1% after 43 000 s continuous operation at - 0.35 V, and decreased by 1.4% after the same working time at 0.8 V. CoFe2O4 hollow microspheres with a diameter of 1-2.5 micron were prepared by a simple two-step calcination method. The initial oxygen reduction potential of the hollow microspheres was - 0.29 V during ORR. The initial oxygen evolution potential of the hollow microspheres was 50 mV lower than that of the irregular CoFe2O4 microspheres in OER, and the current density reached 45 mA cm-2 at 1 V. The ORR current density of CoFe2O4 hollow microspheres decreased by 16.4% and 5.6% after the same working time at - 0.3 V. (4) CoFe2O4/C composite catalyst with three-dimensional network structure was prepared by hydrothermal method using bacterial cellulose as template and carbon source. The initial potential of oxygen reduction of CoFe2O4/C was - 0.09 V and the limiting current density was 5.41 mA cm-2. In the process of OER catalysis, the initial voltage of oxygen evolution was 0.58 V, and the current density was 23.02 mA cm-2 at 1 V. When the CoFe2O4/C composite catalyst was continuously operated at - 0.3 V for 35000 seconds, the ORR current density decreased by 3.7% and 0.8 V. After the same working time, the current density of OER decreases by 5.8%. (5) LixNiCo2-xO4 doped with Li + was prepared by hydrothermal method. The ORR starting potential of Li0.5NiCo1.5O4 was - 0.176 V, the yield of intermediate product was less than 1%, and the electron transfer number was between 3.97-4. Mn2 + doped Mn_xNi1 was also prepared by hydrothermal method. The ORR initiation potential of Mn0.2Ni0.8Co2O4 is -0.13 V when x=0.2. The yield of intermediate product is less than 1.5% and the electron transfer number is between 3.96-4.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TM911.41;O643.36
本文編號：2214647
[Abstract]:Nowadays, the world is experiencing the reform of new energy system. Its main content is to replace fossil-based energy system with new renewable energy, to realize the transition from unsustainable modern industrial civilization to sustainable ecological civilization in the future, and finally to realize the organic integration of human society and the law of the Earth's biosphere cycle. Lithium-air batteries with high theoretical energy density have attracted extensive attention in all new energy storage devices developed. However, the slow kinetics of cathode oxygen reduction reaction (ORR) in the operation of lithium-air batteries will cause overpotential loss, resulting in a large difference between the actual and theoretical energy density and short cycle life. Nowadays, noble metals have good catalytic activity, especially Pt-type catalysts. However, due to the scarcity of precious metal resources and high price, it is difficult to use them in electrochemical catalysis. Therefore, the research and development of non-noble metal catalysts with high catalytic activity is the key to promote the commercialization of lithium-air batteries. In this paper, spinel oxides with good chemical stability, low price and high catalytic activity were selected as the research object, and yeast cells and bacterial cellulose were used as templates and carbon sources to prepare lithium-air batteries. C oFe2O4 and carbon composite catalysts with high catalytic activity and catalytic stability were doped with Li+ and Mn2+ as impurity ions respectively to improve the catalytic activity of NiCo2O4. The main contents and results were as follows: (1) Mesoporous C was prepared by chemical precipitation method using yeast cells as carbon source. OFe2O4/Co/C composite catalysts. Composite products with different electrochemical catalytic properties were prepared by adjusting the concentration of yeast suspension. When the concentration of yeast suspension was 10 g L-1, the specific surface area of the composite product CFO/Co/BC-2 could reach 92.76 M 2 g-1. It had good catalytic activity and catalytic stability under alkaline conditions. In the catalytic process, the initial potential of CFO/Co/BC-2 is - 0.176 V and the limiting current density is 7.25 mA cm-2. In the process of oxygen evolution reaction (OER), the initial potential of oxygen evolution is 0.58 V, and the current density is 26.48 mA cm-2 when the voltage is 1 V. (2) C oFe2O4/C composite microspheres with a diameter of 1-2.5 microrn were prepared by chemical precipitation and freeze-drying using yeast cells as carbon source and template. The C in the composite was the amorphous carbon doped with N and P produced by carbonization of yeast cells. CoFe2O4/C composite microspheres have good catalytic activity and stability under alkaline conditions. In ORR process, the initial potential of oxygen reduction of CoFe2O4/C composite microspheres is only - 0.14 V. In OER catalytic process, the initial potential of oxygen reduction of CoFe2O4/C composite microspheres is only - 0.14 V. The ORR current density of CoFe2O4/C composite microspheres decreased by 15.1% after 43 000 s continuous operation at - 0.35 V, and decreased by 1.4% after the same working time at 0.8 V. CoFe2O4 hollow microspheres with a diameter of 1-2.5 micron were prepared by a simple two-step calcination method. The initial oxygen reduction potential of the hollow microspheres was - 0.29 V during ORR. The initial oxygen evolution potential of the hollow microspheres was 50 mV lower than that of the irregular CoFe2O4 microspheres in OER, and the current density reached 45 mA cm-2 at 1 V. The ORR current density of CoFe2O4 hollow microspheres decreased by 16.4% and 5.6% after the same working time at - 0.3 V. (4) CoFe2O4/C composite catalyst with three-dimensional network structure was prepared by hydrothermal method using bacterial cellulose as template and carbon source. The initial potential of oxygen reduction of CoFe2O4/C was - 0.09 V and the limiting current density was 5.41 mA cm-2. In the process of OER catalysis, the initial voltage of oxygen evolution was 0.58 V, and the current density was 23.02 mA cm-2 at 1 V. When the CoFe2O4/C composite catalyst was continuously operated at - 0.3 V for 35000 seconds, the ORR current density decreased by 3.7% and 0.8 V. After the same working time, the current density of OER decreases by 5.8%. (5) LixNiCo2-xO4 doped with Li + was prepared by hydrothermal method. The ORR starting potential of Li0.5NiCo1.5O4 was - 0.176 V, the yield of intermediate product was less than 1%, and the electron transfer number was between 3.97-4. Mn2 + doped Mn_xNi1 was also prepared by hydrothermal method. The ORR initiation potential of Mn0.2Ni0.8Co2O4 is -0.13 V when x=0.2. The yield of intermediate product is less than 1.5% and the electron transfer number is between 3.96-4.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TM911.41;O643.36
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 席國喜;邢新艷;范仁秀;路邁西;;廢舊鋰離子電池水熱法制備釹摻雜鈷鐵氧體[J];電子元件與材料;2009年01期
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