本文選題：活性炭 + 復(fù)合材料�。� 參考：《海南大學(xué)》2015年碩士論文

【摘要】：為了克服現(xiàn)今商業(yè)鋰離子電池有限的能量密度問(wèn)題,高能量密度二次電池已引起越來(lái)越多的關(guān)注。而其中,鋰硫電池因其高理論比容量、5倍于商業(yè)化LiCoO2的高比能量而尤其被看好。不僅如此,單質(zhì)硫元素還具有價(jià)格低廉、安全無(wú)毒以及來(lái)源豐富等優(yōu)點(diǎn)�？墒�,單質(zhì)硫與放電產(chǎn)物的電導(dǎo)率低以及自身的穿梭效應(yīng)的存在,造成其商業(yè)化進(jìn)程一直遲緩。為了解決這些問(wèn)題,研究者們?cè)絹?lái)越多把目光投入到構(gòu)建可調(diào)的微納米結(jié)構(gòu)正極材料并與硫復(fù)合,而其中硫碳復(fù)合材料往往表現(xiàn)出穩(wěn)定的電化學(xué)性能。因此,本文利用海南優(yōu)勢(shì)資源椰殼制備高比表面積的活性炭為基底制備硫碳復(fù)合材料,并采用XRD、SEM、EDS、TGA以及電化學(xué)測(cè)試等手段對(duì)復(fù)合材料進(jìn)行表征與測(cè)試,討論了椰殼基活性炭作為鋰硫電池正極材料的可能性。 利用KOH活化法制備椰殼基多孔活性炭,通過(guò)對(duì)比實(shí)驗(yàn)表明,經(jīng)過(guò)KOH的活化處理得到了比表面積達(dá)2258.7m2/g的高孔隙率、高比表面積的椰殼基活性炭(HSAAC)。其孔結(jié)構(gòu)主要以微孔為主并存在部分的介孔結(jié)構(gòu)。并用于鋰硫電池的制備,經(jīng)過(guò)電化學(xué)測(cè)試發(fā)現(xiàn)由于其比表面積大、吸附性能強(qiáng)等特點(diǎn),復(fù)合材料在200mA/g的電流密度下首次放電比容量高達(dá)1230mAh/g,100次循環(huán)之后仍然得到929mAh/g的可逆比容量,表現(xiàn)出了較好的電化學(xué)性能。 開(kāi)展了椰殼基多孔活性炭為原料,采用氨水、雙氧水浸責(zé)法對(duì)其進(jìn)行改性,探討了多孔活性炭官能團(tuán)改性對(duì)鋰硫電池電化學(xué)性能的影響。傅里葉紅外圖譜表明,雙氧水改性活性炭在其表面引入了羧基基團(tuán)而氨水改性活性炭在其表面引入了氨基基團(tuán)。經(jīng)電化學(xué)測(cè)試可發(fā)現(xiàn)氨水改性引入了大量的氨基,能顯著提高鋰硫電池的首次放電比容量,由1058mAh/g提高至1333mAh/g;而雙氧水改性在引入了羧基基團(tuán),其首次充放電比容量以及充放電循環(huán)性能都受到了負(fù)面影響。 通過(guò)改變制備工藝參數(shù)得到不同孔結(jié)構(gòu)椰殼基多孔活性炭,并用于鋰硫電池制備及電化學(xué)測(cè)試,研究了具有不同比表面積、孔結(jié)構(gòu)的椰殼基多孔炭負(fù)載單質(zhì)硫制備復(fù)合材料的電化學(xué)性能及孔結(jié)構(gòu)對(duì)其性能的影響。結(jié)果表明：隨著微孔比例上升、中孔比例下降、比表面積增加,制備得的鋰硫電池比容量逐步提高。其中性能最優(yōu)樣品為介孔率為15%,首次放電比容量最高達(dá)1294.5mAh/g,進(jìn)行了100次充放電循環(huán)可逆比容量達(dá)到809.3mAh/g.說(shuō)明微孔結(jié)構(gòu)使得椰殼基活性炭比表面積增加,吸附性能提高,能有效抑制鋰硫電池的穿梭效應(yīng),對(duì)鋰硫電池電化學(xué)性能有著積極的影響。
[Abstract]:In order to overcome the limited energy density of commercial lithium ion batteries, high energy density secondary batteries have attracted more and more attention.Among them, lithium-sulfur batteries are particularly promising for their high theoretical specific capacity of 5 times higher specific energy than commercial LiCoO2.Moreover, elemental sulfur has the advantages of low price, safe and non-toxic and abundant sources.However, the low conductivity of sulfur and discharge products and the existence of its own shuttle effect make its commercialization process slow.In order to solve these problems, researchers are focusing more and more attention on the fabrication of adjustable micro-nano structure cathode materials and compounding with sulfur, among which sulfur and carbon composites often exhibit stable electrochemical properties.Therefore, sulfur and carbon composites were prepared on the basis of high specific surface area activated carbon prepared from coconut shell, a dominant resource in Hainan. The composites were characterized and tested by means of XRDX, SEM, EDSGA and electrochemical measurements.The possibility of coconut shell based activated carbon as cathode material for lithium-sulfur battery was discussed.Coconut shell based porous activated carbon was prepared by KOH activation method. The results showed that the activated carbon with high specific surface area (2258.7m2/g) and high specific surface area (2258.7m2/g) were obtained by KOH activation.The pore structure mainly consists of micropores and some mesoporous structures.And it was used in the preparation of lithium-sulfur battery. It was found by electrochemical test that due to its large specific surface area and strong adsorption properties, the first discharge specific capacity of the composite at current density of 200mA/g was as high as 1230mAh/ g / g / 100 cycle, and the reversible specific capacity of 929mAh/g was still obtained after 100 cycles.It shows good electrochemical performance.The coconut shell based porous activated carbon was modified with ammonia and hydrogen peroxide. The effect of functional group modification of porous activated carbon on the electrochemical performance of lithium sulfur battery was discussed.Fourier transform infrared spectroscopy (FTIR) showed that hydrogen peroxide modified activated carbon introduced carboxyl groups on its surface and ammonia modified activated carbon introduced amino groups on its surface.It was found by electrochemical test that a large amount of amino groups were introduced into the modification of ammonia, and the first discharge specific capacity of lithium-sulfur battery was increased from 1058mAh/g to 1333mAh / g, while the carboxyl group was introduced in the modification of hydrogen peroxide.The first charge-discharge specific capacity and charge-discharge cycle performance are all negatively affected.The porous activated carbon based on coconut shell with different pore structure was obtained by changing the preparation process parameters, and was used in the preparation and electrochemical measurement of lithium sulfur batteries. The specific surface area of the activated carbon with different pore structure was studied.Electrochemical properties of composites prepared by porous carbon supported on porous carbon with porous structure and the effect of pore structure on the properties of composites were investigated.The results show that with the increase of the ratio of micropores, the ratio of mesoporous cells decreases, the specific surface area increases, and the specific capacity of the prepared lithium-sulfur batteries increases gradually.The optimum performance of the sample is the mesoporous ratio of 15, the first discharge specific capacity of 1294.5mAh-1 / g, and the reversible specific capacity of 809.3 mAh/ g for 100 charge-discharge cycles.The results show that the micropore structure can increase the specific surface area of coconut shell activated carbon and enhance the adsorbability of activated carbon. It can effectively inhibit the shuttle effect of lithium sulfur battery and has a positive effect on the electrochemical performance of lithium sulfur battery.
【學(xué)位授予單位】：海南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TM912

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