本文選題：水熱法　切入點(diǎn)：噴霧干燥法　出處：《上海應(yīng)用技術(shù)學(xué)院》2015年碩士論文

【摘要】：在鋰離子電池被廣泛應(yīng)用的形勢下,磷酸鐵鋰因具備生產(chǎn)原料來源廣泛、價(jià)格便宜、材料本身熱穩(wěn)定性好、循環(huán)性能好等優(yōu)點(diǎn)已成為鋰離子電池中最具發(fā)展?jié)摿Φ恼龢O材料。目前,磷酸鐵鋰制備工藝日漸成熟,但依舊存在原料成本高、制備過程污染環(huán)境、制備工藝復(fù)雜、產(chǎn)品性能不足等缺點(diǎn)。針對這些缺點(diǎn),本文以開發(fā)磷酸鐵鋰的綠色低成本合成技術(shù)為主要目的,同時(shí)探究了影響磷酸鐵鋰電化學(xué)性能的因素。1、水熱法可控合成沿(010)晶面和(001)晶面生長的片狀磷酸鐵鋰采用水熱法通過改變原料比例制備了具有(010)晶面取向(即)和(001)晶面取向(即c軸取向)的LiFePO4/C材料。XRD, SEM和HRTEM測試結(jié)果闡述了兩種樣品的晶體生長過程。電化學(xué)性能測試結(jié)果表明,具備(010)晶面取向的磷酸鐵鋰的鋰離子擴(kuò)散速率和比容量均高于具備(001)晶面取向的磷酸鐵鋰,且穩(wěn)定性更高。2、納米球磨制備球形磷酸鐵鋰/C復(fù)合材料及其電化學(xué)性能研究以LiOH·H2O, H3PO4,鐵粉和蔗糖為原料,結(jié)合球磨工藝和噴霧干燥技術(shù)制備多孔球形的磷酸鐵鋰前驅(qū)體,原料在720℃煅燒時(shí)間3h,得到多孔球形的納米LiFePO4/C材料。電化學(xué)結(jié)果表明,在0.2C,0.5C,1C倍率下的放電比容量達(dá)到166.2 mAh/g,160.8 mAh/g,155.2 mAh/g,經(jīng)過10次循環(huán)后的容量保持率均達(dá)到97%以上,具備優(yōu)異的高倍率充放電性能。該材料制備工藝符合綠色低成本的要求,具備工業(yè)化潛力。3、水熱法直接轉(zhuǎn)化磷酸鐵制備高純度的磷酸鐵鋰以LiOH·H2O, FePO4·2H2O為原料(Li:Fe:P=1.35:1:1),蔗糖作為還原劑和碳源,采用水熱法在180℃下保溫4h獲得高純度的LiFePO4/C.該材料具備優(yōu)異的電化學(xué)性能。采用噴霧干燥技術(shù)將水熱產(chǎn)品制備成多孔球形材料,該材料在0.1C,0.2C,0.5C倍率下的首次放電比容量為164.5 mAh/g,161 mAh/g,151.1 mAh/g,經(jīng)過20次循環(huán)后容量幾乎沒衰減,具備優(yōu)異的高倍率電化學(xué)性能。4、水熱法將磷酸鐵轉(zhuǎn)化成為LiFePO4OH合成磷酸鐵鋰的工藝探究以LiOH·H2O, FePO4·2H2O作為原料,通過水熱法在140℃的溫度下制備LiFePO4OH,然后加入12%的蔗糖,將所得溶液進(jìn)行噴霧干燥,將得到的粉末于700℃下煅燒6h,得到樣品(A)。作為對比,另一組實(shí)驗(yàn)不經(jīng)過水熱反應(yīng),直接進(jìn)行噴霧干燥,于800℃煅燒得樣品(B)。結(jié)果表明,以LiFePO4OH中間相最終經(jīng)煅燒合成的LiFePO4/C在0.1C,0.2C,0.5C倍率下,首次充放電比容量為168 mAh/g,157 mAh/g,145 mAh/g,樣品(B)比樣品(A)具備更優(yōu)異的電化學(xué)性能。
[Abstract]:Under the situation that lithium ion battery is widely used, lithium iron phosphate has a wide range of raw materials, low price and good thermal stability. The advantages of good cycling performance have become the most potential cathode materials in lithium ion batteries. At present, the preparation process of lithium iron phosphate is becoming more and more mature, but the raw material cost is high, the preparation process pollutes the environment, and the preparation process is complex. The main purpose of this paper is to develop the green and low cost synthesis technology of lithium iron phosphate. At the same time, the factors affecting the electrochemical performance of lithium ferric phosphate were investigated. The flake lithium ferric phosphate, which grew along the crystal plane of 010) and along the crystal plane, was synthesized by hydrothermal method, and the orientation of the crystal plane was prepared by changing the ratio of raw materials. The crystal growth process of LiFePO4/C material. XRD, SEM and HRTEM with crystal plane orientation (c axis orientation) was described. The electrochemical properties of the two samples were measured. The lithium ion diffusion rate and specific capacity of lithium ferric phosphate with crystal plane orientation are higher than that of lithium iron phosphate with crystal plane orientation, and the diffusion rate and specific capacity of lithium iron phosphate with crystal plane orientation are higher than that of lithium iron phosphate with crystal plane orientation. The spherical lithium ferric phosphate / C composites were prepared by nano-ball milling and their electrochemical properties were studied. Using LiOH _ 2O, H _ 3PO _ 4, iron powder and sucrose as raw materials, the porous spherical lithium iron phosphate precursor was prepared by ball milling and spray drying technology. After calcined at 720 鈩，

本文編號：1688780