鋰硫電池隔膜修飾及正極改性研究
發(fā)布時(shí)間：2018-07-23 09:58
【摘要】：與傳統(tǒng)的鋰離子電池相比,鋰硫二次電池憑借其高比容量(1675 mAh/g)、高能量密度(2600 Wh/kg)、低成本以及環(huán)境友好的優(yōu)點(diǎn)具有更高的經(jīng)濟(jì)利益和發(fā)展前景。然而,鋰硫電池自身的一些物化特性阻礙了其商業(yè)化應(yīng)用:(1)單質(zhì)硫及放電產(chǎn)物L(fēng)i_2S_2/Li_2S具有電子絕緣性;(2)單質(zhì)硫與Li_2S_2/Li_2S密度不同導(dǎo)致體積膨脹;(3)多硫化鋰在電解液中的溶解和穿梭效應(yīng)。本論文以KB@Ir復(fù)合材料作為隔膜修飾層,利用金屬Ir納米顆粒的極性吸附和催化特性,提高了鋰硫電池的電化學(xué)性能。此外還通過將KB@Cu復(fù)合材料作為載體對(duì)電極的電化學(xué)性能進(jìn)行提升。通過優(yōu)化粘結(jié)劑種類對(duì)鋰硫電池電化學(xué)性能及電極活性物質(zhì)載量進(jìn)行優(yōu)化和提升。在此基礎(chǔ)上本論文還成功制備了軟包鋰硫電池。本論文通過微波還原法將金屬Ir納米顆粒均勻沉積在活化后的KB材料表面,成功制備了KB@Ir復(fù)合材料,采用吸附實(shí)驗(yàn)、XPS、CV及Tafel等測試手段對(duì)KB@Ir復(fù)合材料的吸附特性和催化特性進(jìn)行了表征和分析。研究結(jié)果表明KB@Ir復(fù)合材料對(duì)多硫化鋰能夠產(chǎn)生強(qiáng)烈的化學(xué)吸附作用,同時(shí)金屬Ir納米顆粒能夠加速多硫化鋰的轉(zhuǎn)換過程。通過將其作為隔膜修飾層應(yīng)用在鋰硫電池當(dāng)中,顯著提高了電池的電化學(xué)性能。在0.2 C下首次放電容量為1508 mAh/g,即使在2 C的大電流下仍具有653 mAh/g的可逆容量。在1 C倍率下循環(huán)500次后,電池仍具有452mAh/g的放電比容量,每圈容量衰減率為0.105%。通過高溫固相還原法合成了KB@Cu復(fù)合材料,將其作為活性物質(zhì)載體顯著提升了鋰硫電池的電化學(xué)性能,金屬Cu作為極性材料能起到固定硫和多硫化鋰的作用,熱處理過程中金屬Cu會(huì)與單質(zhì)硫反應(yīng)生成CuSx,金屬Cu與單質(zhì)硫之間的強(qiáng)相互作用使得鋰化過程中CuSx能夠直接生成Li2S和單質(zhì)Cu而避免生成可溶性多硫化鋰,同時(shí)金屬Cu能夠提高電極的電子電導(dǎo)率。電化學(xué)測試結(jié)果表明KB@Cu/S復(fù)合材料在0.2 C的倍率下首次放電容量為1003 mAh/g,循環(huán)100次后仍具有508 mAh/g的可逆容量;即使在2 C的倍率下仍具有499 mAh/g的放電比容量。分析PVDF、PEO和GA作為粘結(jié)劑時(shí)對(duì)鋰硫電池的電化學(xué)性能的影響,研究發(fā)現(xiàn)GA作為粘結(jié)劑時(shí)能夠顯著提高鋰硫電池的循環(huán)性能,這是由于GA具有很強(qiáng)的粘結(jié)能力,起到很好的固硫作用,同時(shí)能夠抑制電極在循環(huán)過程中的收縮變形,同時(shí)GA中有很多的含氧官能團(tuán),能夠?qū)Χ嗔蚧嚻鸬交瘜W(xué)固定作用,從而提高活性物質(zhì)利用率。在此基礎(chǔ)上利用GA優(yōu)異的粘結(jié)能力成功制備了硫載量為3.4mg/cm~2的電極極片。本文還在現(xiàn)有工作基礎(chǔ)上成功制備了2 Ah的軟包鋰硫電池,其首次放電容量達(dá)到1784 mAh,并能夠持續(xù)工作超過7000 min。這為鋰硫電池商業(yè)化進(jìn)程的可行性進(jìn)行了初步探索。
[Abstract]:Compared with the traditional lithium-ion battery, the lithium sulfur secondary battery has higher economic benefits and development prospects because of its advantages of high specific capacity (1675 mAh/g), high energy density (2600 Wh-1 / kg), low cost and environmental friendliness. However, some physical and chemical characteristics of lithium sulfur batteries have hindered their commercial applications: (1) simple sulfur and its discharge product Li _ 2S _ 2 / Li _ 2S have electronic insulation; (2) the density of simple sulfur and Li2S _ 2 / Li _ 2S leads to volume expansion; (3) the dissolving and shuttling effect of lithium polysulfide in electrolyte. In this paper, the electrochemical performance of lithium-sulfur battery was improved by using the polar adsorption and catalytic properties of metal ir nanoparticles as the membrane modification layer. In addition, the electrochemical properties of the electrode were improved by using KBbile-Cu composite as the carrier. The electrochemical performance and electrode active material load of lithium sulfur battery were optimized and enhanced by optimizing the binder types. On this basis, the soft-clad lithium-sulfur battery has been successfully fabricated. In this paper, the metal ir nanoparticles were uniformly deposited on the surface of activated KB materials by microwave reduction method, and KBBIL ir composites were successfully prepared. The adsorption and catalytic properties of KBBP ir composites were characterized and analyzed by means of adsorption experiments, XPS CV and Tafel. The results show that the chemical adsorption of lithium polysulfide on KBbilis ir composite is strong, and the metal ir nanoparticles can accelerate the conversion process of lithium polysulfide. The electrochemical performance of lithium-sulfur battery was improved by using it as a membrane modification layer. The initial discharge capacity is 1508 mg / g at 0.2C, and the reversible capacity is 653 mAh/g even at a high current of 2 C. After 500 cycles at 1 C rate, the specific discharge capacity of 452mAh/g is still present, and the attenuation rate of capacity per cycle is 0.105. The high temperature solid state reduction method was used to synthesize KBIL Cu composite, which was used as active material carrier to improve the electrochemical performance of lithium-sulfur battery significantly. Metal Cu as polar material can play the role of fixed sulfur and lithium polysulfide. During heat treatment, Cu reacts with elemental sulfur to form CuSx.The strong interaction between metallic Cu and elemental sulfur makes CuSx produce Li2S and elemental Cu directly, thus avoiding the formation of soluble lithium polysulfide. At the same time, Cu can improve the electronic conductivity of the electrode. The electrochemical test results show that the initial discharge capacity of KBDB-Cu / S composite is 1003 mg / g at the rate of 0.2C, and the reversible capacity of the composite is 508 mAh/g after 100 cycles, and the specific capacity of discharge is 499 mAh/g even at the rate of 2 C. The effect of PVDF PEO and GA as binder on the electrochemical performance of lithium sulfur battery was analyzed. It was found that GA as binder could significantly improve the cycle performance of lithium sulfur battery, which was due to the strong bonding ability of GA. At the same time, there are many oxygen-containing functional groups in GA, which can fix lithium polysulfide chemically and improve the utilization rate of active substances. On this basis, the electrode with sulfur load of 3.4mg/cm~2 was successfully prepared by using the excellent bonding ability of GA. On the basis of the existing work, a 2 Ah soft-coated lithium-sulfur battery has been successfully prepared. The initial discharge capacity of the battery is 1784 mAhh, and it can work continuously for more than 7000 mins. The feasibility of commercial process of lithium-sulfur battery is preliminarily explored.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912;TB33
本文編號(hào)：2139038
[Abstract]:Compared with the traditional lithium-ion battery, the lithium sulfur secondary battery has higher economic benefits and development prospects because of its advantages of high specific capacity (1675 mAh/g), high energy density (2600 Wh-1 / kg), low cost and environmental friendliness. However, some physical and chemical characteristics of lithium sulfur batteries have hindered their commercial applications: (1) simple sulfur and its discharge product Li _ 2S _ 2 / Li _ 2S have electronic insulation; (2) the density of simple sulfur and Li2S _ 2 / Li _ 2S leads to volume expansion; (3) the dissolving and shuttling effect of lithium polysulfide in electrolyte. In this paper, the electrochemical performance of lithium-sulfur battery was improved by using the polar adsorption and catalytic properties of metal ir nanoparticles as the membrane modification layer. In addition, the electrochemical properties of the electrode were improved by using KBbile-Cu composite as the carrier. The electrochemical performance and electrode active material load of lithium sulfur battery were optimized and enhanced by optimizing the binder types. On this basis, the soft-clad lithium-sulfur battery has been successfully fabricated. In this paper, the metal ir nanoparticles were uniformly deposited on the surface of activated KB materials by microwave reduction method, and KBBIL ir composites were successfully prepared. The adsorption and catalytic properties of KBBP ir composites were characterized and analyzed by means of adsorption experiments, XPS CV and Tafel. The results show that the chemical adsorption of lithium polysulfide on KBbilis ir composite is strong, and the metal ir nanoparticles can accelerate the conversion process of lithium polysulfide. The electrochemical performance of lithium-sulfur battery was improved by using it as a membrane modification layer. The initial discharge capacity is 1508 mg / g at 0.2C, and the reversible capacity is 653 mAh/g even at a high current of 2 C. After 500 cycles at 1 C rate, the specific discharge capacity of 452mAh/g is still present, and the attenuation rate of capacity per cycle is 0.105. The high temperature solid state reduction method was used to synthesize KBIL Cu composite, which was used as active material carrier to improve the electrochemical performance of lithium-sulfur battery significantly. Metal Cu as polar material can play the role of fixed sulfur and lithium polysulfide. During heat treatment, Cu reacts with elemental sulfur to form CuSx.The strong interaction between metallic Cu and elemental sulfur makes CuSx produce Li2S and elemental Cu directly, thus avoiding the formation of soluble lithium polysulfide. At the same time, Cu can improve the electronic conductivity of the electrode. The electrochemical test results show that the initial discharge capacity of KBDB-Cu / S composite is 1003 mg / g at the rate of 0.2C, and the reversible capacity of the composite is 508 mAh/g after 100 cycles, and the specific capacity of discharge is 499 mAh/g even at the rate of 2 C. The effect of PVDF PEO and GA as binder on the electrochemical performance of lithium sulfur battery was analyzed. It was found that GA as binder could significantly improve the cycle performance of lithium sulfur battery, which was due to the strong bonding ability of GA. At the same time, there are many oxygen-containing functional groups in GA, which can fix lithium polysulfide chemically and improve the utilization rate of active substances. On this basis, the electrode with sulfur load of 3.4mg/cm~2 was successfully prepared by using the excellent bonding ability of GA. On the basis of the existing work, a 2 Ah soft-coated lithium-sulfur battery has been successfully prepared. The initial discharge capacity of the battery is 1784 mAhh, and it can work continuously for more than 7000 mins. The feasibility of commercial process of lithium-sulfur battery is preliminarily explored.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912;TB33
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 刁巖;謝凱;洪曉斌;熊仕昭;;Li-S電池硫正極性能衰減機(jī)理分析及研究現(xiàn)狀概述[J];化學(xué)學(xué)報(bào);2013年04期
，本文編號(hào)：2139038
本文鏈接：http://sikaile.net/kejilunwen/dianlidianqilunwen/2139038.html
最近更新
教材專著
