本文選題：鋰硫電池 + 硫正極��； 參考：《中南大學》2014年博士論文

【摘要】：摘要：鋰硫電池是一種極具發(fā)展?jié)摿Φ母吣芰棵芏榷武囯姵?其正極材料單質(zhì)硫具有比容量大、成本低廉、環(huán)境友好等優(yōu)點。然而,硫正極也存在諸多缺點：(1)硫及還原產(chǎn)物常溫下具有電子絕緣性；(2)硫電極在充放電過程中會形成易溶于電解液的多硫化物并產(chǎn)生穿梭效應(yīng)；(3)硫電極在充放電循環(huán)中存在較大的體積效應(yīng)。這些因素造成鋰硫電池活性物質(zhì)利用率低、循環(huán)性能差、倍率性能不理想,阻礙了鋰硫電池的實用化。 圍繞解決硫電極存在的關(guān)鍵問題,本論文從設(shè)計、構(gòu)筑硫基復(fù)合材料和電極結(jié)構(gòu)出發(fā),開展了多方面對硫正極的改性研究工作。本文系統(tǒng)研究了不同碳材料對于碳硫復(fù)合材料結(jié)構(gòu)和性能的影響；采用噴霧熱分解法制備了鋰硫電池新型碳硫復(fù)合正極材料；研究了多功能碳紙用于硫正極集流體的電化學性能；采用磁控濺射和電化學沉積導(dǎo)電膜的方法對硫正極進行了極片修飾；設(shè)計并制備了新型鋰硫電池正極結(jié)構(gòu)和導(dǎo)電隔層,研究了其獨特的電化學性能及作用機理。具體研究結(jié)果如下： 采用液相原位沉積的方法制備了碳納米管／硫(CNT/S)、碳纖維／硫(CNF/S)、活性碳／硫(AC/S)和導(dǎo)電炭黑／硫(SP/S)復(fù)合材料,對四種材料的測試結(jié)果比較表明：碳材料的結(jié)構(gòu)和形貌是影響復(fù)合效果的關(guān)鍵因素；多孔碳材料較無孔或少孔碳材料更能改善硫正極的循環(huán)穩(wěn)定性和提高活性物質(zhì)利用率；CNT/S和AC/S復(fù)合材料表現(xiàn)出較好的電化學性能,CNT能提高復(fù)合材料導(dǎo)電性,但復(fù)合均勻度欠佳,實際入孔的有效載硫量有限；AC能有效吸附活性物質(zhì)硫,但導(dǎo)電性欠佳。 采用噴霧熱分解法,以Si02為模板制備了比表面積達1133m2g-1總孔容為2.75cm3g-1的介孔碳球(SPC),并以此作為負載硫的導(dǎo)電基體,制備了介孔碳球／硫復(fù)合材料(SPC/S)。電化學研究表明,碳球的三維結(jié)構(gòu)可以有效增強復(fù)合材料的循環(huán)穩(wěn)定性,0.2C倍率下循環(huán)50次的容量為637mAh g-1,循環(huán)容量保持率為62.9%。此外,碳球內(nèi)部的介孔有利于硫的納米化,能起到限域捕捉活性物質(zhì)和縮短離子擴散路徑的作用,有利于提高材料的倍率性能,1C倍率下仍有470mAh g-1的容量。 在硫正極制備工藝方面,引入商業(yè)碳紙用作正極集流體。電化學研究表明,碳紙作集流體能顯著改善硫正極的循環(huán)穩(wěn)定性,0.2C倍率下循環(huán)100次容量仍有786mAh g-1,循環(huán)容量保持率為89.6%。在正極構(gòu)造中,碳紙既能作為集流體,又能作為負載活性物質(zhì)硫的基體,限域和捕捉溶解的多硫化物,具備多重功能。這種顯著的改善歸因于碳紙具有優(yōu)異的導(dǎo)電性和多孔網(wǎng)絡(luò)骨架結(jié)構(gòu)。 在正極修飾方面,采用磁控濺射噴涂導(dǎo)電碳膜修飾SPC/S復(fù)合正極,0.5C倍率下,鍍碳SPC/S復(fù)合正極首次放電容量為956mAh g-1,50次循環(huán)后容量保持在642mAh g-1,容量保持率提高到67.2%；采用電化學沉積聚苯胺(PANI)導(dǎo)電膜修飾純S正極,0.2C倍率下,PANI涂層S正極首次放電容量為1094mAh g-1,100次循環(huán)后容量保持在725mAh g-1,容量保持率提高到66.3%。研究表明,磁控濺射鍍碳能有效增強電極導(dǎo)電性,減少碳硫復(fù)合材料中活性物質(zhì)的不可逆損失；電化學沉積PANI能形成導(dǎo)電納米網(wǎng)狀結(jié)構(gòu),有效束縛活性物質(zhì)硫,減小多硫化物的溶解和擴散。 在正極結(jié)構(gòu)設(shè)計方面,設(shè)計并制備了兩種在正極和隔膜之間含隔層的鋰硫電池：采用簡單的濾紙?zhí)蓟に嚝@得了性能優(yōu)良的導(dǎo)電碳紙；采用簡單的商業(yè)鎳網(wǎng)壓制工藝獲得了結(jié)構(gòu)穩(wěn)定的導(dǎo)電鎳網(wǎng),分別引入到傳統(tǒng)鋰硫電池中作為隔層使用,其電化學性能獲得了顯著改善。0.2C倍率下,碳紙隔層電池50次循環(huán)后容量保持在810mAh g-1;鎳網(wǎng)隔層電池80次循環(huán)后容量保持在640mAh g-1。碳紙和鎳網(wǎng)隔層的改善作用歸因于它們優(yōu)良的導(dǎo)電性和多孔網(wǎng)絡(luò)結(jié)構(gòu),能夠為絕緣的放電產(chǎn)物提供導(dǎo)電支撐,緩解體積變化,以及吸附多硫化物。
[Abstract]:Abstract: lithium sulfur battery is a lithium battery with high energy density two times a great potential for development, the sulfur cathode material which has large capacity, low cost, environment friendly and other advantages. However, there are also many disadvantages: sulfur cathode (1) with electronic insulation and sulfur reduction products at room temperature (2); the sulfur electrode during the charge discharge process will form polysulfide soluble in the electrolyte and the shuttle effect; (3) there are large volume effect of sulfur electrode during charge / discharge cycles. These factors lead to low utilization of active material of lithium sulfur batteries, poor cycle performance, rate performance is not ideal, hindered the lithium sulfur battery practical.
The key to solve the problem of sulfur electrode existed, this paper from the design, construction of sulfur based composite materials and electrode structure, carry out modification on aspects of sulfur cathode. This paper studied the effect of carbon materials on the structure and performance of carbon sulfur composite; carbon sulfur composite cathode material for lithium sulfur battery prepared by spray thermal decomposition; multi functional carbon paper for the electrochemical performance of sulfur cathode collector was studied; by magnetron sputtering and electrochemical deposition of conductive films were modified on electrode and lithium sulfur cathode; design new cathode structure of sulfur battery and conducting interlayer was prepared and its electrochemical performance was studied and the unique role the mechanism of the specific research results are as follows:
Carbon nanotubes / sulfur were prepared by the method of liquid phase in situ deposition system (CNT/S), carbon fiber / sulfur (CNF/S), activated carbon / sulfur (AC/S) and carbon black (SP/S) / sulfur composites, compared to the four kinds of material test results: the structure and morphology of carbon materials is a key factor affecting composite effect; porous carbon materials is non porous or less porous carbon materials can improve the cycle stability of sulfur cathode and improve the utilization of active material; CNT/S and AC/S composites showed good electrochemical performance, CNT can improve the conductivity of composites, but the composite uniformity is poor, the actual effective load of sulfur into the hole limited; AC can effectively adsorb active substances of sulfur, but the conductivity is poor.
By spray thermal decomposition method, template preparation for mesoporous carbon spheres 2.75cm3g-1 specific surface area of 1133m2g-1 Kong Rong Si02 (SPC), and as the conductive base load of sulfur, mesoporous carbon spheres / sulfur composite materials were prepared (SPC/S). The electrochemical results show that the three dimensional structure of carbon spheres can effectively enhance the cycle stability of composite materials, 0.2C rate 50 cycles the capacity of 637mAh g-1, cyclic capacity retention rate was 62.9%. in addition, the ball inside the mesopores favoring the carbon sulfur nano, can play a role to capture the confinement of active substances and shorten the ion diffusion path, is conducive to improve the rate performance the 1C rate is still 470mAh g-1 capacity.
In the sulfur cathode preparation process, the introduction of commercial carbon paper used as cathode collector. The electrochemical results show that the carbon paper set fluid can significantly improve the cycle stability of sulfur cathode, the 100 Capacity Circulating 0.2C rate is 786mAh g-1, the cycling capacity retention rate of 89.6%. in the cathode structure, carbon paper can be used as collector, and can load active material as the matrix of sulfur and polysulfide confinement and capture dissolved, with multiple functions. This significant improvement is attributed to carbon paper has excellent conductivity and porous structure.
For the modification of cathode by magnetron sputtering coating conductive carbon film modified SPC/S composite cathode, 0.5C, carbon coated SPC/S composite cathode discharge capacity of 956mAh g-1,50 cycling in 642mAh g-1, the capacity retention rate increased to 67.2%; the electrochemical deposition of poly aniline (PANI) pure S anode conductive film modified 0.2C. PANI coated S cathode, the first discharge capacity was 1094mAh g-1100 cycling in 725mAh g-1, the capacity retention rate increased to 66.3%. study showed that the magnetron sputtered carbon can effectively enhance the conductivity of the electrode active material, reduce the carbon sulfur composite material in irreversible loss; electrochemical deposition of PANI can form a conductive nano network structure effective restraint, active material dissolution and diffusion of sulfur, reduce sulfur.
In the cathode structure design, and design two kinds of lithium sulfur battery between the anode and diaphragm containing interlayer were prepared: the excellent properties of the conductive carbon paper by paper carbonization process is simple; the structural stability of the conductive nickel net using a simple commercial nickel net pressing process, was introduced into the traditional lithium used as interlayer the electrochemical performance of sulfur battery, obtained significantly improved.0.2C, capacity to maintain the 810mAh g-1 carbon paper layer battery after 50 cycles; nickel net interlayer battery capacity after 80 cycles in effect 640mAh g-1. carbon paper and nickel net layer due to their excellent electrical conductivity and porous network structure, can provide conductive support for the discharge products of the insulation, relieve volume change, and adsorption of polysulfides.

【學位授予單位】：中南大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM912

【參考文獻】

相關(guān)期刊論文 前5條

1 ;Electrochemical performance of sulfur composite cathode materials for rechargeable lithium batteries[J];Chinese Chemical Letters;2009年10期

2 孫莞檸;應(yīng)皆榮;黃震雷;姜長印;萬春榮;;鋰離子電池有機硫化物電極材料[J];化學進展;2009年09期

3 董全峰;王，

本文編號：1770012