本文選題：鋰空氣電池 + RuO2/MWNTs催化劑�。� 參考：《電子科技大學(xué)》2015年碩士論文

【摘要】：鋰空氣電池因具有非常高的理論比容量引起了研究學(xué)者的廣泛關(guān)注,是一種新型的環(huán)保電池。但是其過大的過電位、較差的倍率性能、較低的循環(huán)壽命等缺點(diǎn)嚴(yán)重阻礙了鋰空氣電池的商業(yè)化進(jìn)程。如今鋰空氣電池的的開發(fā)和研究面臨著許多困難,如:充放電反應(yīng)機(jī)理、負(fù)極鋰片的保護(hù)、電解液的分解、空氣電極的結(jié)構(gòu)設(shè)計(jì)和催化劑的選擇等關(guān)鍵技術(shù)。本論文以探索可以同時(shí)催化鋰空氣電池的氧還原反應(yīng)(ORR)和析氧反應(yīng)(OER)的雙效催化劑為目標(biāo),以RuO2為鋰空氣電池空氣電極的主要催化劑為主要研究對(duì)象,分別采用液相共沉積法和水熱反應(yīng)法制備了不同形貌的RuO2/MWNTs復(fù)合材料,選出具有制備催化性能較好的催化劑的方法,進(jìn)一步利用這種方法在MWNTs表面上同時(shí)負(fù)載納米級(jí)的MnO2和RuO2顆粒,我們利用XRD、SEM、TEM等方法對(duì)復(fù)合材料的物化性能進(jìn)行表征。最后對(duì)由這些復(fù)合材料組裝成的鋰空氣電池進(jìn)行電化學(xué)性能測(cè)試。我們得到如下結(jié)論:1.由水熱反應(yīng)法制備出了RuO2/MWNTs復(fù)合材料中的RuO2結(jié)晶程度比液相共沉積法制備的好,并且具有較小的顆粒粒徑。此外,由水熱反應(yīng)法制備出了RuO2/MWNTs復(fù)合材料表現(xiàn)出較好的電化學(xué)性能,在電流密度為0.1 mA/cm2時(shí),截止電壓為2.3~4.0 V,放電容量高達(dá)2033 mAh/g;電流密度為0.2 m A/cm2時(shí),放電容量為1534 mAh/g,當(dāng)電流密度增加到0.4 mA/cm2時(shí),放電容量衰減到896mAh/g,隨著充放電電流密度的增大,充放電容量明顯減少,過電位緩慢的增加,電極極化增大;電流密度為0.1 mA/cm2時(shí),鋰空氣電池在循環(huán)三周后的放電容量為1808 mAh/g,且具有88.9%的容量保留率,此后在較大的電流密度下進(jìn)行循環(huán)測(cè)試,電流密度為0.3 mA/cm2,截止容量為400 mAh/g,可以循環(huán)50次充放電比容量不發(fā)生衰減且過電壓較小。2.由水熱法進(jìn)一步合成了MnO2-RuO2/MWNTs復(fù)合納米材料,由MnO2-RuO2/MWNTs復(fù)合材料組成的鋰空氣電池在電流密度為0.1 mA/cm2時(shí),具有較大的放電平臺(tái)2.88 V和較小的充電平臺(tái)3.32 V,過電位為0.44 V,該電池的放電比容量值高達(dá)5736 mAh/gcarbon。由MnO2-RuO2/MWNTs復(fù)合材料組成的鋰空氣電池的放電平臺(tái)比RuO2/MWNTs的高0.06 V,且具有較好的放電比容量。此外,由MnO2-RuO2/MWNTs復(fù)合材料組成的鋰空氣電池還具有較好的循環(huán)特性,在電流密度為0.3 mA/cm2,截止容量為1000 mAh/gcarbon(380 mAh/g)時(shí),電池的循環(huán)周期高達(dá)65次,這就表明了MnO2-RuO2/MWNTs復(fù)合材料具有較好的ORR催化活性。3.鋰空氣電池的電化學(xué)性能與催化劑的形貌和納米顆粒的大小密切相關(guān),較小顆粒的催化劑表現(xiàn)出較大的放電容量。納米MnO2的加入可以提高鋰空氣電池的放電電位并提高鋰空氣電池的放電容量和循環(huán)壽命。但較多催化劑的加入會(huì)減少電極的孔容和增加鋰空氣電池的電化學(xué)阻抗。
[Abstract]:Lithium air battery is a new type of environmental protection battery because of its high theoretical specific capacity. However, its shortcomings such as excessive overpotential, poor rate performance and low cycle life seriously hinder the commercialization of lithium-air batteries. Nowadays, the development and research of lithium air battery are facing many difficulties, such as the mechanism of charge and discharge reaction, the protection of cathode lithium, the decomposition of electrolyte, the structure design of air electrode and the selection of catalyst. The aim of this thesis is to explore a dual catalyst that can catalyze the oxygen reduction reaction of lithium-air battery (ORR) and oxygen evolution reaction (ORR) at the same time, and take RuO2 as the main catalyst for the air electrode of lithium-air battery as the main research object. RuO2/MWNTs composites with different morphologies were prepared by liquid phase co-deposition and hydrothermal reaction respectively. Furthermore, the nano-scale MnO2 and RuO2 particles were loaded on the surface of MWNTs by this method, and the physical and chemical properties of the composites were characterized by XRD-SEMT-TEM. Finally, the electrochemical performance of the lithium-air battery assembled from these composite materials was tested. We get the following conclusion: 1. The crystallization degree of RuO2 in RuO2/MWNTs composites prepared by hydrothermal reaction method was better than that by liquid phase co-deposition method, and the particle size was smaller than that prepared by liquid phase co-deposition method. In addition, the RuO2/MWNTs composites prepared by hydrothermal reaction showed good electrochemical properties. When the current density was 0.1 mA/cm2, the cutoff voltage was 2.3N 4.0 V, the discharge capacity was up to 2033 mg / g, and the current density was 0.2 m A/cm2. The discharge capacity is 1534 mg / g. When the current density increases to 0.4 mA/cm2, the discharge capacity attenuates to 896 mg / g. With the increase of charge / discharge current density, the charge-discharge capacity decreases obviously, the overpotential increases slowly and the electrode polarization increases, and when the current density is 0.1 mA/cm2, The discharge capacity of the lithium-air battery is 1808 mg / g after three weeks of cycle and has a retention rate of 88.9%. The current density is 0.3 Ma / cm ~ 2, the cutoff capacity is 400 mg 路h / g, the specific capacity of charging and discharging can be recirculated 50 times without attenuation and the overvoltage is smaller. 2. MnO2-RuO2/MWNTs composite nanomaterials were further synthesized by hydrothermal method. The lithium-air batteries composed of MnO2-RuO2/MWNTs composites were prepared at a current density of 0.1 mA/cm2. The battery has a large discharge platform of 2.88 V and a smaller charging platform of 3.32 V and an overpotential of 0.44 V. the specific discharge capacity of the battery is as high as 5736 mAh/ g carbon. The discharge platform of lithium-air battery composed of MnO2-RuO2/MWNTs composite is 0.06 V higher than that of RuO2/MWNTs, and has good discharge capacity. In addition, the lithium air battery made of MnO2-RuO2/MWNTs composite material also has good cycling characteristics. When the current density is 0.3 Ma / cm ~ 2 and the cutoff capacity is 1000 mAh/gcarbon(380 路h / g, the cycle period of the battery is up to 65 times. This shows that the MnO2-RuO2/MWNTs composite has good ORR catalytic activity. 3. The electrochemical performance of lithium-air batteries is closely related to the morphology of the catalyst and the size of the nanoparticles. The catalyst with smaller particles exhibits a larger discharge capacity. The addition of nanometer MnO2 can increase the discharge potential of lithium air battery and improve the discharge capacity and cycle life of lithium air battery. However, the addition of more catalysts can reduce the pore volume of the electrode and increase the electrochemical impedance of the lithium air battery.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O646.54;TM911.41

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