本文選題：磷酸鐵鋰 + 水��； 參考：《太原理工大學(xué)》2017年碩士論文

【摘要】：能源是當(dāng)今社會(huì)發(fā)展的主要?jiǎng)恿?經(jīng)濟(jì)的高速發(fā)展離不開能源的推進(jìn)作用。目前普遍適用的傳統(tǒng)能源來自于非可持續(xù)再生的煤、石油等,日益不斷的開采,將面臨此類非可持續(xù)資源逐步匱乏的問題,與此同時(shí),傳統(tǒng)非可再生能源的利用過程中,還將面臨嚴(yán)重的環(huán)境問題,諸如溫室氣體的排放等等。新型可再生清潔能源的開發(fā)利用是目前亟待解決的主要問題。其中,風(fēng)能、太陽(yáng)能、潮汐能等新型可再生清潔能源的開發(fā)將為能源領(lǐng)域注入新的活力,將成為替代傳統(tǒng)能源的主要候選之一。然此類能源均屬于非連續(xù)型能源,找尋合適的儲(chǔ)能裝置是推動(dòng)此類能源應(yīng)用發(fā)展的關(guān)鍵。鋰離子電池是目前為止最有潛力的電源系統(tǒng),因其可以提供高的工作電壓及能量密度,而有望用做大規(guī)模能量存儲(chǔ)及電動(dòng)汽車和插電式混合動(dòng)力汽車的車載能量存儲(chǔ)的電池。目前商用鋰離子電池正極材料主要為L(zhǎng)iCoO_2,但這種材料的缺陷較多,例如成本昂貴、安全性能差等。相比于LiCoO_2,LiFePO_4因其原材料價(jià)格低廉、理論容量高、循環(huán)壽命長(zhǎng)且環(huán)境友好等優(yōu)勢(shì),成為目前熱門的正極材料之一。但由于本身晶體結(jié)構(gòu)的限制,其電子電導(dǎo)率和離子傳導(dǎo)率較差,成為阻礙LiFePO_4材料被廣泛應(yīng)用于動(dòng)力及儲(chǔ)能領(lǐng)域的主要因素。本論文采用溶劑熱合成法,以FeSO_4·7H_2O、H_3PO_4、和LiOH·H_2O為原料合成磷酸鐵鋰,應(yīng)用XRD、SEM對(duì)材料的結(jié)構(gòu)及形貌進(jìn)行表征,利用恒電流充放電方法、循環(huán)伏安法及交流阻抗研究所合成磷酸鐵鋰的電化學(xué)性能,綜合考察了合成條件中不同水含量對(duì)磷酸鐵鋰形貌和電化學(xué)性能的影響。同時(shí)通過添加石墨烯,考察不同含量石墨烯對(duì)磷酸鐵鋰電化學(xué)性能的改善。研究表明:合成條件中不同水含量對(duì)所形成的磷酸鐵鋰產(chǎn)物的形貌有很大影響,不同水含量合成條件下,最終形成不同粒子尺寸的磷酸鐵鋰納米片。另外加入不同含量的石墨烯對(duì)磷酸鐵鋰正極材料的電化學(xué)性能有不同程度的優(yōu)化,其中,添加磷酸鐵鋰活性質(zhì)量2%的石墨烯條件下樣品的性能為最佳,通過電化學(xué)性能測(cè)試分析,5 mlH_2O條件下加入石墨烯量為磷酸鐵鋰質(zhì)量2%所合成的材料,在充放電倍率為0.2 C時(shí),達(dá)到165 mAh·g~（-1）的首次放電容量,倍率方面,在30 C充電條件下,仍可保持118.6 mAh·g~（-1）的高比容量,并在5 C電流密度下,循環(huán)100次后比容量仍能得到很好的保持,不會(huì)發(fā)生衰減。
[Abstract]:Energy is the main driving force of social development, and the rapid development of economy can not be separated from the role of energy. At present, the traditional energy sources that are generally applicable come from the non-sustainable renewable coal, oil and so on. With the increasing exploitation of such non-sustainable resources, they will face the problem of the gradual scarcity of such non-sustainable resources. At the same time, in the process of using traditional non-renewable energy, Will also face serious environmental problems, such as greenhouse gas emissions and so on. The development and utilization of new renewable clean energy is the main problem to be solved. Among them, the development of new renewable clean energy, such as wind energy, solar energy, tidal energy and so on, will inject new vitality into the energy field, and will become one of the main candidates for replacing traditional energy. However, these kinds of energy are discontinuous energy sources, and finding suitable energy storage devices is the key to promote the development of such energy applications. Li-ion battery is the most potential power system by far, because it can provide high working voltage and energy density, it is expected to be used as a battery for large-scale energy storage and on-board energy storage for electric vehicles and plug-in hybrid vehicles. At present, LiCoO2is the main cathode material for commercial lithium-ion batteries, but there are many defects in this material, such as high cost, poor safety performance and so on. Compared with LiCoO2LiFePO4, it has become one of the most popular cathode materials due to its advantages of low raw material price, high theoretical capacity, long cycle life and environmental friendliness. However, due to the limitation of its crystal structure, its electronic conductivity and ionic conductivity are poor, which is the main factor that hinders the wide application of LiFePO_4 materials in the field of power and energy storage. In this paper, lithium iron phosphate was synthesized by solvothermal synthesis from FeSO_4 7H _ 2OH _ 2O _ 3PO _ 4 and LiOH _ H _ 2O as raw materials. The structure and morphology of the material were characterized by XRD-SEM, and the constant current charge-discharge method was used. The electrochemical properties of lithium iron phosphate synthesized by cyclic voltammetry and impedance spectroscopy were investigated. The effects of water content on the morphology and electrochemical properties of lithium iron phosphate were investigated. At the same time, the improvement of electrochemical performance of lithium iron phosphate with different content of graphene was investigated by adding graphene. The results show that different water content has great influence on the morphology of the synthesized lithium ferric phosphate products. Finally, different particle sizes of lithium iron phosphate nanoparticles are formed under different water content synthesis conditions. In addition, the electrochemical properties of lithium ferric phosphate cathode materials were optimized by adding different contents of graphene, and the best performance of the samples was obtained when the active mass of lithium iron phosphate was 2% of graphene. The first discharge capacity of the material prepared by adding 2% graphene to lithium ferric phosphate at a charge / discharge rate of 0.2C reached 165 mAh / g ~ (-1) at 30 C charging condition was analyzed by electrochemical performance test. The high specific capacity of 118.6 mAh / g ~ (-1) can still be maintained at 5 C current density, and the specific capacity can still be maintained very well after 100th cycle without decay.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM912

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本文編號(hào)：1957561