本文關(guān)鍵詞： 淤漿法 聚陰離子纖維素鹽 靜電紡絲 鋰電池 水性粘結(jié)劑　出處：《北京理工大學(xué)》2015年博士論文　論文類(lèi)型：學(xué)位論文

【摘要】：本文利用核磁、化學(xué)分析等方法與手段對(duì)捏合法和淤漿法制備的聚陰離子纖維素鈉(CMC-Na)的取代基在葡萄糖單元(AGU)及鏈上基團(tuán)結(jié)構(gòu)分布做了分析比較。發(fā)現(xiàn)淤漿法制備的產(chǎn)品C6位上的長(zhǎng)鏈結(jié)構(gòu)要多于捏合法,斷裂伸長(zhǎng)率基本在12%左右,比捏合法生產(chǎn)的產(chǎn)品8%要高,鏈柔順性更高。采用淤漿法產(chǎn)品兩步制備新的聚陰離子纖維素鹽—羧甲基纖維素鋰(CMC-Li),在35℃下用20%的酸進(jìn)行酸化2h得到CMC-H,再在50℃下堿化2h得到CMC-Li,優(yōu)化制備工藝,建立測(cè)試方法。CMC-Li比CMC-Na具有更明顯的非牛頓流體的特性,熱穩(wěn)定性能相當(dāng)。采用聚環(huán)氧乙烷(PEO)作為共溶劑與淤漿法制備的聚陰離子纖維素鹽在純水中形成電紡液,在電壓為30~36KV,紡絲距離為15cm,濃度4%,速率為1~4ml/h,聚陰離子纖維素鹽的分子量小于10萬(wàn)時(shí)能得到表面光滑,直徑較小(約70nm)且均一的納米纖維材料;利用靜電紡絲技術(shù)包覆碳量子點(diǎn)熒光材料得到具有熒光特性的CMC-Na無(wú)紡布,發(fā)射波長(zhǎng)為510nm;利用靜電噴霧技術(shù)制備CMC-Na微球,形貌較好,單分散性較好;通過(guò)同軸靜電紡絲技術(shù),成功制備了CMC-Na中空的納米纖維。通過(guò)靜電紡絲將CMC-Li電紡液和鋁粉(Al)顆粒共同電紡,制備Al/CMC-Li納米復(fù)合纖維。通過(guò)SEM、TEM表征了所得到的各種纖維材料的形貌及包覆顆粒分散情況。研究利用靜電紡絲技術(shù),將納米纖維的優(yōu)良特性和聚陰離子纖維素鹽的結(jié)構(gòu)特性結(jié)合,實(shí)現(xiàn)了聚陰離子纖維素鹽新溶劑電紡法,拓展延伸了纖維素衍生物的應(yīng)用范圍。利用靜電紡絲技術(shù)制備了CMC-Li和鋰電池正極材料磷酸鐵鋰(LiFePO4,LFP)顆�；旌侠w維,并進(jìn)行高溫碳化改性,得到新型改性電極材料。將CMC-Li/LFP納米纖維復(fù)合材料進(jìn)行285℃預(yù)氧化2h控制碳含量在10%以下,在600℃進(jìn)行氮?dú)獗Ｗo(hù)下高溫碳化1h,CMC-Li最終以碳納米纖維(CNFs)、Li+氧化物鹽的形式存在,與LFP顆粒進(jìn)行充分的混合,形成CNFs/LFP/Li+鹽(簡(jiǎn)稱(chēng)CLL)充分混合的新型改性電極材料。以PVDF為粘結(jié)劑,LFP和CLL分別為電極材料組裝成鋰電池進(jìn)行性能測(cè)試,發(fā)現(xiàn)CLL電極材料基電池的首次充放電比容量最高分別達(dá)到了168 mAh g-1和161 mAh g-1,分別比未經(jīng)改性的LFP電極提高了15.1%和11.8%,經(jīng)過(guò)200圈0.1C充放電循環(huán)以后,幾乎沒(méi)有損耗。當(dāng)放電倍率從0.1C、0.2C增大到5C,電池的比容量依舊達(dá)到了120.5 mAh g-1,當(dāng)放電倍率再?gòu)?C降低到0.1C,鋰電池的比容量可迅速回到167.5mAh g-1。CV的氧化還原峰比較尖銳對(duì)稱(chēng),差值最小達(dá)到0.25V。這些表明,通過(guò)這種方法能有效的提高正極材料的導(dǎo)電性,縮短鋰離子的擴(kuò)散路徑,降低極化程度和增強(qiáng)電化學(xué)性能。首次將制備的含鋰離子的水性粘結(jié)劑CMC-Li應(yīng)用到正極材料LFP上,建立CMC-Li材料中鋰離子脫出和嵌入移動(dòng)的模型。結(jié)果表明,CMC-Li粘結(jié)劑基的電池其首次充放電比容量達(dá)到183.8 mAh g-1和179.5 mAh g-1,分別比以油溶性PVDF粘結(jié)劑提高了22.2%和27.5%,經(jīng)過(guò)200圈循環(huán)以后,放電比容量達(dá)到175mAh g-1,比容量損耗3.31%,不同倍率0.1C到5C之間的循環(huán)性能較優(yōu),CV測(cè)試的差值最小達(dá)到0.22V,EIS性能較小都體現(xiàn)出較優(yōu)的電化學(xué)活性較。實(shí)現(xiàn)以低分子量CMC-Li靜電紡絲改性LFP,形成了納米纖維熔融層包裹LFP的改性電極CLL,并以高分子量的CMC-Li作為粘結(jié)劑組裝成鋰電池復(fù)合電極進(jìn)行性能測(cè)試,對(duì)增強(qiáng)鋰電池性能的過(guò)程機(jī)理進(jìn)行了理論分析與探究。結(jié)果表明,CMC-Li-6作為粘結(jié)劑和CLL-3作為活性物質(zhì)的復(fù)合電極材料顆粒形貌成微球型,電解液浸潤(rùn)更充分,首次0.1C充放電比容量最高為179.5 mAh g-1和176.8 mAh g-1,經(jīng)過(guò)100圈循環(huán)以后,比容量沒(méi)有減少,反而增加,最終充放電比容量分別為181.7 mAh g-1和180.6mAh g-1,并且循環(huán)效率一直接近100%。當(dāng)進(jìn)行大倍率5C進(jìn)行充放電,依舊能保持在115 mAh g-1、CV峰之間的差值為0.20V,屬于電化學(xué)性能優(yōu)良的新型電池。
[Abstract]:In this paper, using NMR, chemical analysis methods and means of kneading and slurry prepared by polyanionic cellulose sodium (CMC-Na) substituent in glucose unit (AGU) and chain group structure distribution is analysed and compared. It is found that slurry prepared by C6 products on the chain structure than kneading, fracture the elongation is about 12%, higher than the kneading products 8%, the chain flexibility is higher. The slurry products two step preparation of new polyanionic cellulose carboxymethyl cellulose lithium salt (CMC-Li), under the temperature of 35 DEG C with 20% acid acidification 2H CMC-H, then at 50 DEG C Solonetzic 2H CMC-Li, optimizing the preparation process, the establishment of.CMC-Li test method has more obvious non Newtonian properties than CMC-Na, thermal stability. Using polyethylene oxide (PEO) as co solvent and slurry prepared by polyanionic cellulose salt in water In the formation of electro spinning solution, the voltage is 30~36KV, the spinning distance is 15cm, the concentration of 4%, rate of 1~4ml/h, the molecular weight of poly anionic cellulose salt is less than 100 thousand can get smooth surface, smaller diameter (about 70nm) nano fiber material and uniform; using electrospinning coated carbon quantum dot fluorescent material CMC-Na non-woven fabric with fluorescence, the emission wavelength is 510nm; CMC-Na microsphere preparation, the use of electrostatic spraying technology for satisfactory morphology and good monodispersity; through coaxial electrospinning technology, CMC-Na hollow nanofibers were prepared by electrospinning. The electrospun CMC-Li liquid and powder (Al) particles electrospinning system preparation of Al/CMC-Li nano composite fiber. By SEM, TEM was characterized by a variety of fiber morphology and dispersion of coated particles. Using the electrospinning technique, the excellent properties of nano fiber and poly anionic fiber In combination with the structural properties of salt, the salt of polyanionic cellulose solvent electrospinning method, expand the scope of application of cellulose derivatives. The CMC-Li lithium battery and lithium iron phosphate cathode material prepared by electrospinning (LiFePO4, LFP) particles mixed fiber, and the high temperature carbonization modification, new change electrode materials. CMC-Li/LFP nano fiber composite materials was 285 DEG C pre oxidation of 2H to control the carbon content below 10%, are under the protection of nitrogen high temperature carbonization at 600 C for 1H CMC-Li with carbon nano fiber (CNFs), Li+ oxide salt, thoroughly mixed with LFP particles, the formation of salt (referred to as CNFs/LFP/Li+ CLL) new modified electrode materials are fully mixed. Using PVDF as binder, LFP and CLL respectively as the electrode material assembled into lithium battery performance testing, found that the first discharge electrode materials of CLL based battery capacity than most The high reached 168 mAh g-1 and 161 mAh g-1 respectively than without LFP modified electrodes increased by 15.1% and 11.8%, after 200 cycles of 0.1C charge discharge cycle, almost no loss. When the discharge rate from 0.1C, 0.2C increased to 5C, the specific capacity of the battery still reached 120.5 mAh g-1, when the discharge then the ratio decreased from 5C to 0.1C, the ratio of lithium battery capacity can be quickly returned to the 167.5mAh g-1.CV of the redox peak sharp symmetry, the minimum value reached 0.25V. this shows that through this method can effectively improve the electrical conductivity of the cathode, shorten the diffusion path of lithium ion, reduce the degree of polarization and enhance the electrochemical performance of system for the first time. The preparation of lithium ion containing water binder CMC-Li applied to the LFP cathode material, a lithium ion insertion and extraction of mobile model CMC-Li materials. The results showed that CMC-Li binder based battery charge and discharge volume for the first time The amount of up to 183.8 mAh g-1 and 179.5 mAh g-1, respectively, compared with oil soluble PVDF binder increased by 22.2% and 27.5%, after 200 cycles, the discharge capacity reached 175mAh g-1, more than 3.31% capacity loss, different ratio of 0.1C to 5C between the cycle performance is better than the CV test the difference reached 0.22V, EIS the performance of small shows better electrochemical activity. In order to achieve the low molecular weight CMC-Li electrospinning modified LFP formed electrode modified with nano CLL fiber melting layer package LFP, and the molecular weight of CMC-Li as binder assembled into composite electrode of lithium battery performance testing, to enhance the process performance of lithium batteries the analysis and Research of the theory. The results show that CMC-Li-6 as a binder and CLL-3 as composite electrode active material particle morphology of microspheres, the electrolyte infiltration more fully, the first charge discharge capacity highest 0.1C 179.5 mAh g-1 and 176.8 mAh g-1, after 100 cycles, the capacity ratio did not decrease, but increased, the final charge discharge were 181.7 mAh g-1 and 180.6mAh g-1 than the capacity and cycle efficiency has been close to 100%. when the rate of 5C charge and discharge, still can be maintained at 115 mAh g-1, the difference between CV peaks for the 0.20V, is a new type of battery with excellent electrochemical properties.

【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：O636.11;TM912

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本文編號(hào)：1513521