鋰硫電池正極材料的制備及結(jié)構(gòu)設(shè)計(jì)
發(fā)布時(shí)間：2018-11-15 10:33
【摘要】：近年來,隨著能源危機(jī)的日益加重,以及電子電動(dòng)設(shè)備的迅猛發(fā)展,研究清潔的可持續(xù)能源已逐漸成為一個(gè)研究熱點(diǎn)。鋰硫電池因其具有高理論比容量(1675 m Ah/g)和能量密度(2600 Wh/kg),被公認(rèn)為是最具有發(fā)展前景的能源存儲(chǔ)體系之一。同時(shí),鋰硫電池還具有單質(zhì)硫資源地殼含量豐富,成本低廉和對(duì)環(huán)境友好等優(yōu)點(diǎn)。然而硫及其放電產(chǎn)物硫化鋰的電子絕緣性,硫放電過程中的產(chǎn)生的中間產(chǎn)物多硫化物易溶于電解液中并向負(fù)極遷移,從而造成的“穿梭效應(yīng)”以及硫電極在充放電循環(huán)中的體積膨脹都嚴(yán)重的影響鋰硫電池的電化學(xué)性能。針對(duì)以上問題,本文主要通過采用將單質(zhì)硫與碳進(jìn)行復(fù)合的方法進(jìn)行改善,主要的實(shí)驗(yàn)有以下三個(gè)方面:1.我們選用生物質(zhì)廢棄物稻殼為原材料經(jīng)過簡(jiǎn)單的煅燒和氫氧化鉀活化,制備了一種SiO_2修飾的多孔碳。采用熔融浸漬法制備了碳硫復(fù)合材料,并表征其作為鋰硫電池正極材料的性能。含有SiO_2吸附質(zhì)的多孔碳可兼具微孔固硫及化學(xué)吸附雙重固硫作用,表現(xiàn)出優(yōu)良的電化學(xué)性能。2.我們以生物質(zhì)廢棄物玉米芯為來源經(jīng)過簡(jiǎn)單的煅燒和氫氧化鉀活化制度,制備了納米片微孔碳。通過熔融浸漬法制備了碳硫復(fù)合材料,并表征其作為鋰硫電池正極材料時(shí)的性能。納米片層的玉米芯微孔碳能夠增加電子的電導(dǎo)率并能縮短離子的傳輸路徑,增大材料與電解液的接觸面積,在合適的粘結(jié)劑海藻酸鈉存在下表現(xiàn)出了優(yōu)越的循環(huán)穩(wěn)定性及倍率性能。3.我們選取廉價(jià)易得的天然高分子材料海藻酸鹽,經(jīng)過簡(jiǎn)單的活化,制備了一系列的比表面積、孔容和孔隙度可調(diào)的富含含氧官能團(tuán)的碳材料。并探討了不同物理結(jié)構(gòu)的碳材料同電性能間的關(guān)系。在碳材料同時(shí)具備合適的孔容及孔結(jié)構(gòu)分布時(shí),能夠容納活性物質(zhì)體因而獲得了優(yōu)異的電化學(xué)循環(huán)性能及倍率性能。這些對(duì)材料微觀結(jié)構(gòu)、表面化學(xué)與電化學(xué)性能之間關(guān)系的研究可以很好的指導(dǎo)我們以后對(duì)碳基體材料的合理設(shè)計(jì)。4.我們選取聚丙烯腈為原料,利用可批量化生產(chǎn)的靜電紡絲技術(shù),制備了一種氮摻雜的碳纖維膜。該碳纖維膜可用作鋰硫電池正極集流體,與硫復(fù)合后可獲得無導(dǎo)電劑無粘結(jié)劑的高能量密度的一體化正極。該正極良好的電化學(xué)性能歸因于可調(diào)的電極孔隙度及雜原子摻雜導(dǎo)致的化學(xué)鍵合多硫化物作用。
[Abstract]:In recent years, with the aggravation of energy crisis and the rapid development of electronic electric equipment, the research of clean and sustainable energy has become a research hotspot. Because of its high theoretical specific capacity (1675 m Ah/g) and energy density (2600 Wh/kg), lithium-sulfur battery is recognized as one of the most promising energy storage systems. At the same time, lithium-sulfur batteries have the advantages of rich crustal content of simple sulfur resources, low cost and environmental friendliness. However, the electronic insulation of sulfur and its discharge product lithium sulphide, the intermediate product polysulfide produced during the discharge of sulfur, is easily dissolved in the electrolyte and migrated to the negative electrode. As a result, the "shuttle effect" and the volume expansion of the sulfur electrode in the charge / discharge cycle seriously affect the electrochemical performance of the lithium sulfur battery. In view of the above problems, this paper mainly adopts the method of compounding simple sulfur and carbon to improve, the main experiment has the following three aspects: 1. A kind of porous carbon modified by SiO_2 was prepared by simple calcination and activation of potassium hydroxide with biomass waste rice husk as raw material. Carbon and sulfur composites were prepared by melt impregnation and their properties as cathode materials for lithium sulfur batteries were characterized. The porous carbon containing SiO_2 adsorbate has both microporous sulfur fixation and chemisorption double sulfur fixation, showing excellent electrochemical performance. 2. Nanoscale microporous carbon was prepared from biomass waste corncob by simple calcination and potassium hydroxide activation system. Carbon and sulfur composites were prepared by melt impregnation and their properties as cathode materials for lithium-sulfur batteries were characterized. The nanoscale corncob micropore carbon can increase the electron conductivity, shorten the ion transport path, and increase the contact area between the material and the electrolyte. In the presence of suitable binder sodium alginate, it showed excellent cycling stability and rate performance. 3. A series of oxygen rich carbon materials with adjustable specific surface area, pore volume and porosity were prepared by simple activation of alginate, a cheap and easily available natural polymer material. The relationship between electrical properties and carbon materials with different physical structures is also discussed. When the carbon material has a suitable pore volume and pore structure distribution, it can accommodate the active materials and thus obtain excellent electrochemical cycling performance and rate performance. These studies on the relationship between the microstructure, surface chemistry and electrochemical properties of the materials can be used to guide the reasonable design of carbon matrix materials in the future. 4. Using polyacrylonitrile (pan) as raw material, a nitrogen-doped carbon fiber film was prepared by batch electrospinning technique. The carbon fiber film can be used as the positive collector of lithium-sulfur battery, and the integrated positive electrode with high energy density without conductive agent can be obtained when the carbon fiber film is combined with sulfur. The excellent electrochemical performance is attributed to the adjustable porosity of the electrode and the chemically bonded polysulfide due to the doping of hetero atoms.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912
本文編號(hào)：2333058
[Abstract]:In recent years, with the aggravation of energy crisis and the rapid development of electronic electric equipment, the research of clean and sustainable energy has become a research hotspot. Because of its high theoretical specific capacity (1675 m Ah/g) and energy density (2600 Wh/kg), lithium-sulfur battery is recognized as one of the most promising energy storage systems. At the same time, lithium-sulfur batteries have the advantages of rich crustal content of simple sulfur resources, low cost and environmental friendliness. However, the electronic insulation of sulfur and its discharge product lithium sulphide, the intermediate product polysulfide produced during the discharge of sulfur, is easily dissolved in the electrolyte and migrated to the negative electrode. As a result, the "shuttle effect" and the volume expansion of the sulfur electrode in the charge / discharge cycle seriously affect the electrochemical performance of the lithium sulfur battery. In view of the above problems, this paper mainly adopts the method of compounding simple sulfur and carbon to improve, the main experiment has the following three aspects: 1. A kind of porous carbon modified by SiO_2 was prepared by simple calcination and activation of potassium hydroxide with biomass waste rice husk as raw material. Carbon and sulfur composites were prepared by melt impregnation and their properties as cathode materials for lithium sulfur batteries were characterized. The porous carbon containing SiO_2 adsorbate has both microporous sulfur fixation and chemisorption double sulfur fixation, showing excellent electrochemical performance. 2. Nanoscale microporous carbon was prepared from biomass waste corncob by simple calcination and potassium hydroxide activation system. Carbon and sulfur composites were prepared by melt impregnation and their properties as cathode materials for lithium-sulfur batteries were characterized. The nanoscale corncob micropore carbon can increase the electron conductivity, shorten the ion transport path, and increase the contact area between the material and the electrolyte. In the presence of suitable binder sodium alginate, it showed excellent cycling stability and rate performance. 3. A series of oxygen rich carbon materials with adjustable specific surface area, pore volume and porosity were prepared by simple activation of alginate, a cheap and easily available natural polymer material. The relationship between electrical properties and carbon materials with different physical structures is also discussed. When the carbon material has a suitable pore volume and pore structure distribution, it can accommodate the active materials and thus obtain excellent electrochemical cycling performance and rate performance. These studies on the relationship between the microstructure, surface chemistry and electrochemical properties of the materials can be used to guide the reasonable design of carbon matrix materials in the future. 4. Using polyacrylonitrile (pan) as raw material, a nitrogen-doped carbon fiber film was prepared by batch electrospinning technique. The carbon fiber film can be used as the positive collector of lithium-sulfur battery, and the integrated positive electrode with high energy density without conductive agent can be obtained when the carbon fiber film is combined with sulfur. The excellent electrochemical performance is attributed to the adjustable porosity of the electrode and the chemically bonded polysulfide due to the doping of hetero atoms.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912
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