【摘要】：因具有較高的工作電壓、能量密度、長(zhǎng)壽命和對(duì)環(huán)境友好等特點(diǎn)，鋰離子電池已經(jīng)成為新一代電動(dòng)汽車(chē)、電動(dòng)工具及電子產(chǎn)品的動(dòng)力電源，已經(jīng)廣泛應(yīng)用于能源、交通、通訊等不同的領(lǐng)域之中。目前，新一代高比能正極材料的開(kāi)發(fā)已經(jīng)成為鋰離子電池的一個(gè)研究熱點(diǎn)。富鋰錳基正極材料因?yàn)榫哂懈弑饶芰�，低成本等�?yōu)點(diǎn)，被認(rèn)為下一代高比能鋰離子電池的正極材料候選材料之一。然而，這種材料存在電子導(dǎo)電性能較差、首次效率較低、循環(huán)性能較差等問(wèn)題，并且材料在實(shí)際電池中的電化學(xué)性能研究較少，在一定程度上限制了該材料的商業(yè)化應(yīng)用。本論文不但在實(shí)驗(yàn)室中進(jìn)行了材料合成與材料改性研究，，以求提高該材料的電化學(xué)性能，還使用該材料進(jìn)行了實(shí)效電池的制作和性能測(cè)試，取得了實(shí)效電池性能的第一手?jǐn)?shù)據(jù)，為該材料的產(chǎn)業(yè)化提供了基礎(chǔ)數(shù)據(jù)。 首先，利用共沉淀法合成了性能優(yōu)異的前驅(qū)體材料Ni0.21Co0.12Mn0.67CO3，且通過(guò)對(duì)材料燒結(jié)溫度、配鋰量的優(yōu)化，合成了一種性能較優(yōu)的富鋰錳基正極材料Li[Li0.17Ni0.17Co0.10Mn0.56]O2，由前驅(qū)體和碳酸鋰混合均勻后在850℃下燒結(jié)得到，材料結(jié)晶性能較好、顆粒的大小適中，材料在充放電過(guò)程中形成的SEI膜的阻抗較小。材料電化學(xué)性能表明材料具有較低的首次不可逆容量，良好的循環(huán)性能：在2.0~4.6V0.05C電流下，50次循環(huán)后容量保持率為88%，首次充、放電比容量分別為298.1mAh g-1和256.1. mAh g-1。其次，富鋰錳基正極材料Li[Li0.17Ni0.17Co0.10Mn0.56]O2表面的包覆改性：對(duì)該材料包覆具有電化學(xué)活性的LiCoPO4。包覆后循環(huán)性能得到了提升，并且我們對(duì)性能改善的原因進(jìn)行了機(jī)理方面的初步探索LiCoPO4結(jié)構(gòu)較穩(wěn)定，能承受較高的充電電壓，材料表面包覆LiCoPO4后，表面的LiCoPO4隔絕了富鋰錳基正極材料與電解液的直接接觸，能夠有效阻止材料與電解液的反應(yīng)，從而改善了材料電化學(xué)性能；最后通過(guò)實(shí)效電池制作，發(fā)現(xiàn)電池在循環(huán)中有氣體產(chǎn)生，并證明該材料在實(shí)效電池中會(huì)析出氧氣，通過(guò)實(shí)效電池電化學(xué)性能研究，發(fā)現(xiàn)該材料用于實(shí)效電池正極材料仍有待進(jìn)一步研究。
[Abstract]:Because of its high working voltage, energy density, long life and environmental friendliness, lithium-ion battery has become a new generation power supply for electric vehicles, electric tools and electronic products, and has been widely used in energy and transportation. In different fields, such as communications. At present, the development of a new generation of high specific energy cathode materials has become a research hotspot in lithium ion batteries. Lithium-rich manganese based cathode materials are considered as candidates for the next generation of high specific energy lithium-ion batteries because of their advantages of high specific energy and low cost. However, this kind of material has some problems, such as poor electronic conductivity, low initial efficiency and poor cycling performance, and the electrochemical performance of the material in the actual battery is less, which limits the commercial application of the material to some extent. In this paper, not only the material synthesis and material modification were studied in order to improve the electrochemical performance of the material, but also the actual battery was made and the performance test was carried out, and the firsthand data of the actual battery performance was obtained. It provides the basic data for the industrialization of the material. Firstly, Ni _ (0.21) Co _ (0.12) mn _ (0.67) CO _ 3 precursor with excellent properties was synthesized by coprecipitation method. Li [Li 0.17Ni0.17Co0.10Mn0.56] O _ 2, a Li-rich manganese-rich cathode material, was synthesized and sintered at 850 鈩

本文編號(hào)：2122025