本文選題：錳酸鋰 + 正極材料�。� 參考：《中國海洋大學》2014年碩士論文

【摘要】：鋰離子電池作為儲能材料被用于手機、照相機、手提電腦、電動車及混合動力汽車等領(lǐng)域。其中，鋰離子電池的正極材料在其結(jié)構(gòu)中占有舉足輕重的地位。錳系氧化物鋰鹽正極材料因為其工作電壓高，原材料豐富，價格便宜，安全性好，環(huán)境友好等優(yōu)點，得到了廣泛關(guān)注，在動力汽車等市場的具有很高的應(yīng)用前景。但由于其較低的比容量，使用過程中容量衰減和循環(huán)性能差等原因，使其應(yīng)用受到了一定的限制。通過陽離子取代錳離子的位置，對氧化錳鋰進行摻雜形成固溶體，是提高氧化錳鋰材料循環(huán)性能的重要方法。 本論文采用共沉淀法，主要通過三種陽離子對錳酸鋰進行了改性研究。利用X射線衍射儀（XRD），掃描電子顯微鏡（SEM）對材料晶體結(jié)構(gòu)、表觀形貌和化學成分進行了分析表征，以分析晶體的結(jié)構(gòu)變化，顆粒的尺寸與形貌改變對材料性能的影響，從而優(yōu)化材料的電化學性能；采用恒電流充放電測試技術(shù)對其電化學性能進行測定分析，探索最佳元素摻雜量。 （1）通過研究鋰離子對氧化錳鋰的影響可以發(fā)現(xiàn)，隨著鋰離子含量的減少，，其晶體結(jié)構(gòu)會發(fā)生明顯的變化，正極材料的物相發(fā)生改變。隨著鋰離子含量的減少，材料的放電容量呈下降趨勢，充放電電壓平臺逐漸清晰。Li1.15Mn2O4材料為層狀-尖晶石型復合材料，即0.09Li2MnO3·0.91LiMn2O4，材料表現(xiàn)出良好的電化學性能，其結(jié)構(gòu)中的Li2MnO3在充放電過程中能穩(wěn)定尖晶石結(jié)構(gòu)，使材料表現(xiàn)出良好的電化學穩(wěn)定性。 （2）通過研究鎳離子對錳酸鋰的影響可以發(fā)現(xiàn)，鎳離子的加入會使尖晶石結(jié)構(gòu)發(fā)生細微的變化，材料的晶格收縮。鎳離子的摻入可以細化晶體顆粒大小，提高材料顆粒的均一性，進而減小了鋰離子的擴散路徑，提高其高倍率放電性能，但是較小的顆粒對循環(huán)性能影響較大。鎳離子的加入能明顯提高材料的放電電壓，使材料具有較高的比功率。 （3）通過研究鈷離子對錳酸鋰的影響可以發(fā)現(xiàn)，鈷離子的摻入可以明顯的改變晶體的微觀形貌，使得晶體生長時按一定的方向優(yōu)先生長。當鈷的摻雜量達到0.1時，Li1.15Mn1.9Co0.1O4材料呈規(guī)則的正八面體，具有良好的電化學性能，鈷離子的加入會對錳酸鋰材料的容量有明顯的損耗，但對其循環(huán)性能有一定的改善。在循環(huán)充放電過程中，Li1.15Mn1.9Co0.1O4的放電容量分為大致三個階段，上升，保持，略微下降，晶體結(jié)構(gòu)中鈷離子的加入能提高材料結(jié)構(gòu)的穩(wěn)定性，使其在使用過程中表現(xiàn)出較穩(wěn)定的電化學性能。
[Abstract]:Lithium-ion batteries are used as energy storage materials for mobile phones, cameras, laptops, electric vehicles and hybrid vehicles.Among them, the cathode material of lithium ion battery plays an important role in its structure.Because of its advantages of high working voltage, abundant raw materials, low price, good safety and environmental friendliness, manganese oxide cathode materials have been widely concerned, and have high application prospects in the market of power vehicles and so on.However, its application is limited due to its low specific capacity, capacity attenuation and poor cycle performance.It is an important method to improve the cycling performance of manganese lithium oxide material by doping lithium manganese oxide into solid solution by replacing manganese ion with cations.In this paper, lithium manganese oxide was modified by three kinds of cations by co-precipitation method.The crystal structure, apparent morphology and chemical composition of the material were characterized by X-ray diffractometer and scanning electron microscope (SEM), in order to analyze the change of crystal structure and the influence of the change of particle size and morphology on the properties of the material.In order to optimize the electrochemical performance of the material, the constant current charge-discharge test technique was used to determine and analyze the electrochemical performance of the material, and to explore the best doping amount of elements.1) by studying the effect of lithium ion on lithium manganese oxide, it can be found that with the decrease of lithium ion content, the crystal structure will change obviously and the phase of cathode material will change.With the decrease of lithium ion content, the discharge capacity of the material decreased, and the charging and discharging voltage platform became clear. Li1.15Mn2O4 was a layered spinel composite, that is, 0.09Li2MnO3 0.91 limn _ 2O _ 4, which showed good electrochemical properties.The Li2MnO3 in the structure can stabilize the spinel structure during charging and discharging, which makes the material exhibit good electrochemical stability.2) by studying the effect of nickel ion on lithium permanganate, it is found that the addition of nickel ion can make the spinel structure change slightly and the lattice shrink of the material.The addition of nickel ion can refine the size of crystal particles, improve the uniformity of material particles, reduce the diffusion path of lithium ion, and improve the discharge performance of lithium ion at high rate, but the smaller particles have a great effect on the cycling performance.The addition of nickel ion can obviously increase the discharge voltage of the material and make the material have higher specific power.3) by studying the effect of cobalt ion on lithium permanganate, it can be found that the doping of cobalt ion can obviously change the morphology of crystal and make the crystal grow in a certain direction.When the doping amount of cobalt is 0.1, Li1.15Mn1.9Co0.1O4 is a regular octahedron and has good electrochemical performance. The addition of cobalt ion will have obvious loss to the capacity of lithium manganese oxide, but it can improve its cycling performance to a certain extent.The discharge capacity of Li1.15Mn1.9Co0.1O4 is divided into three stages: rising, keeping and decreasing slightly. The addition of cobalt ion in crystal structure can improve the stability of the material structure.The results show that the electrochemical performance is stable in the process of application.
【學位授予單位】：中國海洋大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM912

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