本文選題：微型無人機 + 鋰-硫電池��； 參考：《南京航空航天大學》2014年碩士論文

【摘要】：鋰-硫電池是以金屬鋰為負極，單質(zhì)硫為正極的二次電池，因其具有高的理論比容量(1675mAh·g-1)及理論能量密度(2600Wh·kg-1),成為最具發(fā)展?jié)摿Φ男滦透吣芑瘜W電源體系之一。另外，硫儲量豐富、成本低廉，環(huán)境友好，是一種“綠色電池”。但是鋰-硫電池仍存在一些問題：一是單質(zhì)硫和它的還原產(chǎn)物硫化鋰低電導率使其活性物質(zhì)利用率低；二是硫電極的放電中間產(chǎn)物多硫化鋰易溶于有機電解液中，這些易溶的多硫化鋰進而擴散到鋰負極，與負極鋰反應生成低價多硫化鋰，使負極鋰腐蝕同時發(fā)生自放電。然后這些多硫化鋰再擴散回到硫正極，從而引起活性物質(zhì)的損失。這種“穿梭效應”的發(fā)生，嚴重制約了硫電極的循環(huán)穩(wěn)定性。本文圍繞提高硫的比容量以及循環(huán)穩(wěn)定性的研究目的，制備性能優(yōu)異的復合正極材料,為研制長航時微型無人機的電源系統(tǒng)提供理論和科學依據(jù)。主要研究內(nèi)容包括： (1)硫被封裝入以可溶性淀粉為碳源，針狀納米Mg(OH)2為模板制備的分級多孔碳(HPC)中。HPC具有高的比表面積902.5m2·g-1和大的孔體積2.60cm3·g-1。在S/HPC復合材料中硫含量高達84%。在高的電流密度1675mA·g-1下，S/HPC復合正極材料首次放電比容量高達1249mAh·g-1。經(jīng)循環(huán)100圈，庫倫效率高達94%，同時具有穩(wěn)定的循環(huán)性能。S/HPC復合正極材料優(yōu)良的電化學性能與HPC獨特的結(jié)構(gòu)密切相關。HPC具有大孔、介孔和微孔的分級多孔石墨結(jié)構(gòu)。這種納米結(jié)構(gòu)的HPC能夠在循環(huán)過程中縮短離子和電子的傳輸路徑。 (2)以管狀聚吡咯(T-PPY)為原料合成多孔氮摻雜的碳納米管(PNCNT)，其具有高的比表面積(1765m2·g-1)和大的孔體積(1.28cm3·g-1)。PNCNT的內(nèi)徑和壁厚分別約為55nm和22nm。具有優(yōu)異性質(zhì)的PNCNT用于封裝硫能夠成為一個優(yōu)異的復合正極材料應用于高性能鋰-硫電池。在1C的電流密度下，S/PNCNT復合正極材料首次放電比容量為1341mAh·g-1。在50圈循環(huán)后，可逆比容量仍保持在933mAh·g-1。PNCNT良好的電化學性能歸因于它自身優(yōu)異的導電性，大比表面積，氮摻雜和獨特的孔徑分布。 (3)硫被限制在以金屬有機框架化合物(MOF-5)一步法熱解的分級多孔碳納米片(HPCN)中。HPCN片層平均約50nm厚，呈現(xiàn)出三維的分級多孔納米結(jié)構(gòu)，具有高的比表面積(1645m2·g-1)和大的孔體積(1.18cm3·g-1)。電化學證明HPCN/S復合材料具有高比容量和良好的循環(huán)性能。在0.1C的電流密度下，HPCN/S的首次放電比容量為1177mAh·g-1。即使在0.5C的電流密度下，循環(huán)50圈后它的放電比容量仍然有730mAh·g-1，同時庫侖效率高達97%。HPCN/S復合正極材料加強的電化學性能和HPCN優(yōu)異的三維多孔片的納米結(jié)構(gòu)密切相關。這種結(jié)構(gòu)在充放電過程中不僅可以提供穩(wěn)定的電子和離子傳輸通道，而且對多硫化物強吸附作用和緩沖體積變化起到關鍵作用。 (4)以碳納米管和氧化石墨烯(CNTs/GO)為主體材料，通過化學還原法制備了CNTs/GO負載硫的復合正極材料CNTs/GO/S。掃描電子顯微鏡(SEM)及透射電子顯微鏡(TEM)測試表明，，CNTs均勻插層在GO片間，從而形成三維多孔結(jié)構(gòu)，有利于電解液的浸潤；活性物質(zhì)硫均勻地負載在CNTs/GO表面。電化學測試表明，CNTs/GO/S復合材料具有高的比容量和良好的循環(huán)穩(wěn)定性：在1C電流密度下，復合材料首次放電比容量高達904mAh·g-1，經(jīng)過50圈循環(huán)之后復合材料的比容量仍保持在578mAh·g-1。
[Abstract]:Lithium sulfur battery is the two battery with metal lithium as negative electrode and elemental sulfur as positive pole. Because of its high theoretical specific capacity (1675mAh. G-1) and theoretical energy density (2600Wh. Kg-1), lithium sulfur battery has become one of the most promising new high-energy chemical power systems. In addition, the sulfur reserves are rich, low cost and friendly environment. But it is a "green battery". There are still some problems in lithium sulphur batteries: one is the sulfur and its reduction product, the low conductivity of the lithium sulfide, low utilization of the active substance, and two is the intermediate product of the sulfur electrode, which is easy to dissolve in the organic electrolyte. These easily dissolved lithium sulfide and then spread to the lithium anode, and the reaction with the negative lithium can produce low sulfur and multi vulcanization. Lithium, which causes negative lithium corrosion at the same time, occurs at the same time from discharge. Then these lithium sulfide re diffuses back to the sulfur positive electrode, which causes the loss of the active substance. This "shuttle effect" seriously restricts the cyclic stability of the sulfur electrode. This paper focuses on the purpose of improving the specific capacity of sulfur and the stability of the cyclic sulfur. The positive pole material provides theoretical and scientific basis for developing the power supply system of the long endurance micro UAV.
(1) sulfur is encapsulated with soluble starch as carbon source and needle like nano Mg (OH) 2 as a template for graded porous carbon (HPC) with high specific surface area 902.5m2. G-1 and large pore volume 2.60cm3. G-1. in S/HPC composite materials with high current density 1675mA g-1. Up to 100 cycles, up to 100 cycles of 1249mAh. G-1., the efficiency of Kulun is up to 94%, and it has stable cyclic performance. The excellent electrochemical performance of the.S/HPC composite positive electrode is closely related to the unique structure of HPC..HPC has a porous graphite structure with large pores, mesoporous and microporous. This nanostructured HPC can shorten the ion and electricity during the cycle process. The transmission path of the child.
(2) synthesis of porous nitrogen doped carbon nanotube (PNCNT) with tubular polypyrrole (T-PPY) as a raw material, which has high specific surface area (1765m2. G-1) and large pore volume (1.28cm3. G-1).PNCNT, which has excellent properties for 55nm and 22nm., respectively, for encapsulation of sulfur, which can be used as an excellent composite positive material. Performance of lithium sulfur batteries. Under the current density of 1C, the initial discharge ratio of S/PNCNT composite cathode material is 1341mAh. G-1. at 50 cycles. The reversible specific capacity remains at 933mAh g-1.PNCNT good electrochemical performance due to its excellent electrical conductivity, large surface area, nitrogen doping and unique pore size distribution.
(3) sulfur is restricted to an average of about 50nm thickness in the.HPCN lamellar layer of graded porous carbon nanoscale (HPCN) by one step pyrolysis of metal organic framework compound (MOF-5), showing a three-dimensional porous nanostructure with a high specific surface area (1645m2. G-1) and large pore volume (1.18cm3. G-1). Electrochemistry shows that the HPCN/S composite has a high specific capacity. Under the current density of 0.1C, the initial discharge ratio of HPCN/S is 1177mAh. G-1., even at the current density of 0.5C, after 50 cycles, the discharge specific capacity is still 730mAh g-1, and the coulomb efficiency is higher than that of the 97%.HPCN/S composite positive electrode material and the excellent three dimensional porous film of HPCN. The structure of rice is closely related. This structure can not only provide a stable electron and ion transmission channel, but also play a key role in the strong adsorption of polysulfide and the change of the buffer volume.
(4) using carbon nanotubes and graphene oxide (CNTs/GO) as the main material, the CNTs/GO/S. scanning electron microscope (SEM) and transmission electron microscope (TEM) test of CNTs/GO supported sulfur based composite positive material by chemical reduction method showed that the uniform intercalation of CNTs was between the GO slices, thus forming a three-dimensional porous structure, which was beneficial to the infiltration of the electrolyte; The material sulfur is uniformly loaded on the CNTs/GO surface. The electrochemical test shows that the CNTs/GO/S composite has high specific capacity and good cyclic stability. At the 1C current density, the composite material's initial discharge capacity is up to 904mAh. G-1. After 50 cycles, the specific capacity of the composite remains at 578mAh g-1..
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：O613.71;TM912

【共引文獻】

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