本文關(guān)鍵詞：富鋰錳基鋰離子正極材料制備與性能研究　出處：《北京有色金屬研究總院》2014年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 鋰離子電池 正極材料 富鋰層狀材料 控制結(jié)晶法 氫氧化物共沉淀

【摘要】：隨著電子產(chǎn)品的功能不斷增多,對鋰離子電池提出了更高要求：質(zhì)輕、長巡航時間、經(jīng)久耐用、高安全性能和更低成本等。本文以高容量、低成本的富鋰高錳鋰離子電池正極材料為目標,重點開展了層狀固溶體材料xLi2Mn03·(1-x)LiM02的制備及其電化學性能研究,主要完成了如下研究工作： 首先,設(shè)計了高容量層狀富鋰相材料xLi2Mn03·(1-x)LiMO2(M=Ni1/3Co1/3Mn1/3,0x1),即xLi[Li1/3Mn2/3]O2·(1-x)LiNi1/3Co1/3Mn1/3O2組成的體系固溶體材料,通過復合金屬氫氧化物前驅(qū)體—高溫固相轉(zhuǎn)化法進行了探索性合成方法研究,利用XRD、 XPS、ICP、TEM、SEM等表征手段,研究了材料的化學組成、顆粒形貌、元素價態(tài)和晶體結(jié)構(gòu),采用扣式電池恒電流充放電測試方法研究了材料的電化學性能。 其次,采用連續(xù)共沉淀控制結(jié)晶晶體生長方法合成了上述所設(shè)計的固溶體材料相對應的5種鎳鈷錳氫氧化物前驅(qū)體,研究了EDTA和NH3·H2O二種配位劑對這些球形前驅(qū)體的微結(jié)構(gòu)、元素價態(tài)與電化學性能的影響,選用EDTA為混合配位劑,以更簡便可靠工藝合成出了組成可控、高密度、球形富鋰錳基正極材料氫氧化物前驅(qū)體,取代了慣用的以NH3·H2O作為配位劑的合成思路。前驅(qū)體濕法合成最佳工藝參數(shù)：EDTA的合理用量在2.5g/L,反應溫度50±2℃,反應體系pH控制在11.2，反應及晶體生長設(shè)計不宜超過50h,電機攪拌頻率為38Hz。 再次,采用“兩步煅燒”方式,在空氣氣氛中將氫氧化物前驅(qū)體進行高溫鋰化轉(zhuǎn)化合成富鋰高錳鋰離子電池正極材料,通過采用均勻設(shè)計的方法,較方便快捷的獲得了高溫燒結(jié)條件,最佳燒結(jié)條件為：過鋰量3%,預燒溫度480℃,預燒時間5h,燒結(jié)溫度900℃,燒結(jié)時間10小時。獲得了較優(yōu)異的富鋰正極材料。 最后,對合成的系列富鋰高錳材料進行了微結(jié)構(gòu)及電化學性能表征。在晶體結(jié)構(gòu)方面,該材料具有典型的層狀六方a-NaFeO2結(jié)構(gòu)(空間群為R3m)。在XRD圖譜中可以觀察到(006)/(012)和(108)/(110)峰有明顯地分裂,表明該材料具有很好的二維層狀結(jié)構(gòu)。同時,從圖中可以看出在200-25°之間出現(xiàn)一組較小的衍射峰,這是由于Li2Mn03的過渡金屬層由Li/Mn=1/2的比例交替排列,具有超品格有序性。 測試了不同X值的xLi[Li1/3Mn2/3]O2·(1-x)LiMO2樣品的電化學性能,x=0.6樣品(即Li[Li0.20Mn0.54Ni0.13Co0.13O2)具有最高的首次放電比容量為252.3mAh/g。另通過不同干燥方式考察了前驅(qū)體價態(tài)對xLi[Li1/3Mn2/3]O2(1-x)LiMO2電化學性能的影響。
[Abstract]:With the increasing function of electronic products, the requirements of lithium-ion batteries are higher: light weight, long cruise time, durability, high safety performance and lower cost. The preparation and electrochemical properties of layered solid solution (xLi2Mn03 路1-xLiM02) for lithium-rich lithium-ion batteries with low cost were studied. The following research work has been completed: First of all, the high capacity layered lithium-rich phase material, xLi2Mn03 路1-xLiMO2 / Ni1 / 3Co1 / 3Mn1 / 3Mn1, or xLi, was designed. [Li1/3Mn2/3] O _ 2 路Li _ (1-x) LiNi1 / 3Mn1 / 3O2 solid solution material. The synthetic method of composite metal hydroxide precursor and high temperature solid phase transformation was studied, and characterized by means of XRD, XPSN ICP Tem SEM and so on. The chemical composition, particle morphology, elemental valence state and crystal structure of the materials were studied. The electrochemical properties of the materials were studied by means of constant current charge / discharge test of button batteries. Secondly, five kinds of nickel-cobalt-manganese hydroxide precursors corresponding to the above designed solid solution materials were synthesized by the method of continuous coprecipitation controlled crystal growth. The effects of EDTA and NH3 路H2O on the microstructure, valence state and electrochemical properties of these spherical precursors were studied. EDTA was selected as the mixed coordination agent. The hydroxide precursor with controllable composition, high density and spherical lithium-rich manganese base cathode material was synthesized by a more simple and reliable process. Instead of the conventional synthesis of NH3 路H2O as the coordination agent, the optimum technological parameter of the wet synthesis of precursor is 2.5 g / L, and the reaction temperature is 50 鹵2 鈩，

本文編號：1413297