【摘要】：鋰離子電池是人類應(yīng)對能源危機最重要的手段之一,正極材料作為鋰電池重要的組成部分,其性能好壞直接影響電池的各項性能。開發(fā)高性能、低成本的新型正極材料一直是鋰離子電池的研究方向。作為鋰離子電池正極材料,層狀三元鎳鈷錳酸鋰具有比容量高、循環(huán)性能好,成本低、安全性好等優(yōu)點,被認(rèn)為是最具開發(fā)應(yīng)用前景、實現(xiàn)替代Li CoO2電極材料的新型正極材料之一,目前該材料已經(jīng)逐步走向市場,應(yīng)用領(lǐng)域不斷擴(kuò)大,尤其是在電動汽車(EV)和混合電動汽車領(lǐng)域(HEV),也具有相當(dāng)大的發(fā)展空間。本文采用共沉淀法作為層狀鎳鈷錳酸鋰的合成方法,通過液相共沉淀方法制備前驅(qū)體Ni1/3Co1/3Mn1/3(OH)2,通過高溫固相反應(yīng)制備三元正極材料LiNi_(l/3)Co_(1/3)Mn_(l/3)O_2。以LiNi_(l/3)Co_(1/3)Mn_(l/3)O_2正極材料為研究對象,系統(tǒng)研究了不同合成工藝對目標(biāo)材料物化性能及電性能的影響,主要通過X射線衍射(XRD)分析、掃描電子顯微鏡(SEM)分析、熱重差熱(TG-DTA)分析、恒電流充放電測試等方法分別對產(chǎn)品形貌、晶體結(jié)構(gòu)和電化學(xué)性能進(jìn)行表征和測試。在采用液相共沉淀方法制備Nil/3Co1/3Mnl/3(OH)2前驅(qū)體過程中,本論文著重研究了pH值、金屬離子濃度、沉淀劑濃度、絡(luò)合劑濃度對前驅(qū)體的影響。實驗結(jié)論證明,將反應(yīng)溶液的pH值控制在10.5左右,金屬離子濃度2 mol·L-1,沉淀劑濃度為4mol·L-1,絡(luò)合劑濃度為3 mol·L-1,此時的Nil/3Co1/3Mnl/3(OH)2前驅(qū)體顆粒粒徑整體分布窄,形貌類似球體。在采用高溫固相法制備LiNi_(l/3)Co_(1/3)Mn_(l/3)O_2正極材料過程中,本論文著重研究了固相反應(yīng)溫度、固相反應(yīng)時間,以及不同Li/(Ni+Co+Mn)摩爾配比對產(chǎn)物的影響。實驗結(jié)論證明,Li/M(Ni+Co+Mn)=1.05/1,高溫?zé)Y(jié)900℃恒溫12h,得到三元層狀正極材料LiNi_(l/3)Co_(1/3)Mn_(l/3)O_2。充放電電壓區(qū)間為4.3~2.75V,倍率為0.2C,首次放電比容量為154.50mAh·g-1,容量保持率高,經(jīng)過20次循環(huán)后容量保持率為92.91%。
[Abstract]:Lithium ion battery is one of the most important means to deal with the energy crisis. As an important component of lithium battery, the performance of cathode material directly affects the performance of the battery. Developing new cathode materials with high performance and low cost has always been the research direction of lithium ion batteries. As a cathode material of lithium ion battery, layered lithium nickel cobalt manganese oxide has many advantages, such as high specific capacity, good cycling performance, low cost and good safety, so it is considered to be the most promising for development and application. One of the new cathode materials to replace the Li CoO2 electrode material has gradually moved to the market, and the application field has been expanding constantly, especially in the electric vehicle (EV) and hybrid electric vehicle field (HEV), also has a considerable development space. The precursor Ni1/3Co1/3Mn1/3 (OH) _ 2 was prepared by liquid phase coprecipitation, and the ternary cathode material LiNi_ (l / 3) Co_ (1 / 3) Mn_ (l / 3) O _ 2 was prepared by high temperature solid state reaction. Taking LiNi_ (1 / 3) Co_ (1 / 3) Mn_ (l / 3) O _ 2 cathode material as the research object, the effects of different synthetic processes on the physical and chemical properties and electrical properties of the target materials were systematically studied. The results were analyzed by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) (SEM) analysis and thermogravimetric differential thermogravimetry (TG-DTA) analysis. The morphology, crystal structure and electrochemical properties of the products were characterized and tested by constant current charge-discharge test. In the process of preparing Nil/3Co1/3Mnl/3 (OH) _ 2 precursor by liquid-phase coprecipitation, the effects of pH value, metal ion concentration, precipitation agent concentration and complexing agent concentration on the precursor were studied in this paper. The experimental results show that the pH value of the reaction solution is about 10. 5, the concentration of metal ions is 2 mol L -1, the concentration of precipitator is 4mol L -1, and the concentration of complex agent is 3 mol L -1. The particle size distribution of the precursor of Nil/3Co1/3Mnl/3 (OH) 2 is narrow and the morphology is similar to that of the sphere. In the process of preparing LiNi_ (l / 3) Co_ (1 / 3) Mn_ (l / 3) O _ 2 cathode material by high temperature solid state method, the effects of solid state reaction temperature, solid state reaction time and different molar ratio of Li/ (Ni Co Mn) on the product were studied in this paper. The experimental results show that the ternary layered cathode material LiNi_ (l / 3) Co_ (1 / 3) Mn_ (l / 3) O _ 2s can be obtained by sintering at 900 鈩，

本文編號：2240856