本文選題：鋰硫電池　切入點：正極材料　出處：《山東大學(xué)》2017年碩士論文

【摘要】：作為地球上儲量豐富且理論能量密度較高的元素之一,硫在能量儲存尤其是在鋰硫電池的研究應(yīng)用中有著十分重要的作用。然而,由于多硫化物的"穿梭效應(yīng)"、硫在充放電過程中的體積膨脹及單質(zhì)硫的導(dǎo)電性差等原因使鋰硫電池的商業(yè)化應(yīng)用至今面臨著巨大的挑戰(zhàn)。因此,研發(fā)新型的鋰硫電池正極材料改善鋰硫電池性能已成為研究的重點。本論文以金屬有機框架與還原氧化石墨的復(fù)合物(MIL-100(V)/rGO)和以牛蒡根莖為金屬來源的均勻分散的金屬氟化物(CaF2和MgF2)兩種新型原料為對象,研究金屬有機框架及金屬氟化物中在鋰硫電池中的應(yīng)用。主要研究內(nèi)容如下:(1)用水熱的方法制備介孔MIL-100(V),并創(chuàng)新性地在水熱合成過程中引入氧化石墨烯,成功合成了 MIL-100(V)/rGO復(fù)合物。本論文首次將這兩種材料負(fù)載硫用作鋰硫電池正極材料并對其電化學(xué)性能進行了研究。金屬有機框架MIL-100(V)獨特的介孔結(jié)構(gòu)以及較大的比表面積為硫的載入提供了基礎(chǔ),而V3+和V4+兩種價態(tài)同時存在的金屬釩離子對多硫化物的溶解起到了更強的抑制作用。此外,還原氧化石墨烯(rGO)的引入有效地緩沖了充放電過程中硫的體積變化,提供了快速的鋰離子擴散通道,從而進一步提高了材料的電子導(dǎo)電性。(2)以牛蒡根莖為原料,經(jīng)過空氣中的高溫煅燒和氫氟酸溶液浸泡兩個過程,將牛蒡根莖中含量豐富的Ca、Mg元素提取出來,生成鈣、鎂均勻分散的且具有介孔結(jié)構(gòu)的CaF2和MgF2混合物(CMF),首次實現(xiàn)了以生物質(zhì)為原料來制備金屬氟化物并將這種材料負(fù)載硫研究金屬氟化物在鋰硫電池中的應(yīng)用。在載硫量高達(dá)75%時,在0.1 C(1 C=1675 mAh g-1)電流密度下循環(huán)100圈,其比容量還可以維持在650 mAh g-1。在0.5 C電流密度下循環(huán)300圈,仍然能保持530 mAhg-1的比容量。CMF優(yōu)異的電化學(xué)性能表明金屬氟化物作為一種新型材料,將對鋰硫電池新材料的研究和發(fā)展產(chǎn)生巨大的影響。
[Abstract]:As one of the elements with abundant reserves and high theoretical energy density on earth, sulfur plays an important role in energy storage, especially in the research and application of lithium-sulfur batteries. Due to the "shuttle effect" of polysulfide, the volume expansion of sulfur in charge and discharge process and the poor conductivity of sulfur, the commercial application of lithium-sulfur batteries has been faced with great challenges. The development of new cathode materials for lithium-sulfur batteries to improve the performance of lithium-sulfur batteries has become the focus of research. In this paper, the metal-organic framework and reduced graphite complex MIL-100V / rGO) and the uniform distribution of gold from Arctium lappa root as metal source. It belongs to two new materials of fluoride, CaF2 and MgF2. The applications of organometallic frameworks and metal fluoride in lithium sulfur batteries are studied. The main contents are as follows: 1) hydrothermal method to prepare mesoporous MIL-100 VN, and to introduce graphene oxide into hydrothermal synthesis process. MIL-100(V)/rGO complex was successfully synthesized. In this thesis, the two materials were used as cathode materials for lithium-sulfur batteries for the first time and their electrochemical properties were studied. Unique mesoporous structure and large ratio Table of Metalorganic frame MIL-100V. The area provides the basis for sulfur loading, The vanadium ions of V _ 3 and V _ 4 have a stronger inhibitory effect on the dissolution of polysulfide. In addition, the introduction of reductive graphene oxide can effectively buffer the volume change of sulfur during charge and discharge. A fast lithium ion diffusion channel is provided, which further improves the electronic conductivity of the material. It uses burdock rhizome as raw material, which is calcined at high temperature in air and soaked in hydrofluoric acid solution. Calcium was obtained from the root stem of Arctium lappa, which was rich in Ca and mg, and was extracted from the rhizome of Arctium lappa. The homogeneous and mesoporous CaF2 and MgF2 mixtures of magnesium have been used to prepare metal fluorides from biomass for the first time and to study the application of metal fluoride in lithium-sulfur batteries. The specific capacity can be maintained at 650 mAh g ~ (-1) at the current density of 0.1 C ~ (1) C ~ (1) C ~ (1) C ~ (16 75 mAh g ~ (-1)), and the specific capacity can also be maintained at a current density of 0.5 C. The excellent electrochemical properties of the metal fluoride, which can still maintain the specific capacity of 530 mAhg-1, indicate that the metal fluoride, as a new material, will have a great influence on the research and development of the new materials for lithium sulfur batteries.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB332;TM912

【相似文獻】

相關(guān)碩士學(xué)位論文 前1條

1 侯雅萍;新型鋰硫電池正極載硫材料的研究[D];山東大學(xué);2017年

，

本文編號：1667958