本文選題：Li1.016Cr0.103Mn0.464Ni0.356O2　切入點(diǎn)：溶膠凝膠法　出處：《河北工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：本文以Li[Li1/3Mn2/3]O2-Li Cr O2-Li Ni1/2Mn1/2O2組成的體系為研究對(duì)象,采用溶膠凝膠法合成了五種三元富鋰Li-Ni-Mn-Cr-O正極材料,研究了Cr與Mn+Ni的摩爾比(設(shè)Cr/Mn+Ni為x,x=0.44,0.38,0.29,0.21,0.15以下簡(jiǎn)稱A~E)和水洗對(duì)材料的結(jié)構(gòu)和電化學(xué)性能的影響,選擇出較優(yōu)的材料。然后對(duì)較優(yōu)的材料進(jìn)行條件優(yōu)化,詳細(xì)考察了反應(yīng)溫度、溶劑種類、檸檬酸與過(guò)渡金屬比、煅燒溫度和煅燒時(shí)間對(duì)材料電化學(xué)性能的影響,最后對(duì)材料進(jìn)行了摻雜和包覆研究。通過(guò)XRD進(jìn)行材料結(jié)構(gòu)表征,SEM進(jìn)行材料表面形貌表征和分析,ICP進(jìn)行元素含量的測(cè)定,EIS、CV、恒流充放電測(cè)試進(jìn)行電化學(xué)性能分析。過(guò)渡金屬和檸檬酸摩爾比為1:1,調(diào)節(jié)p H=7,55℃合成A~E系列前驅(qū)體,400℃預(yù)燒4h,800℃煅燒12h,制備出的樣品都具有層狀結(jié)構(gòu),但有很強(qiáng)的吸濕性;經(jīng)水洗處理未改變晶體結(jié)構(gòu),提高了該系列材料的電化學(xué)性能;實(shí)驗(yàn)證明,水洗溶出物為L(zhǎng)i2Cr O4。其中,E樣品水洗處理后(Li1.016Cr0.103Mn0.464Ni0.356O2)的電化學(xué)性能最好。繼續(xù)對(duì)Li1.016Cr0.103Mn0.464Ni0.356O2優(yōu)化,以水作溶劑、檸檬酸與過(guò)渡金屬配比為1:1、85℃的反應(yīng)溫度、800℃下煅燒12h。合成的Li1.016Cr0.103Mn0.464Ni0.356O2具有典型的富鋰層狀的晶體結(jié)構(gòu)。材料在2.0~4.8V,0.1C下首次放電比容量為190.2m Ah/g,經(jīng)過(guò)20次充放電循環(huán)后,容量保持率為86.0%。利用溶膠凝膠法對(duì)Li1.016Cr0.103Mn0.464Ni0.356O2進(jìn)行Co、Al摻雜,得到Li1.016Cr0.103Mn0.464-x Ni0.356Nx O2(x=0.01,0.02,0.03,0.04),討論了不同摻雜量對(duì)Li1.016Cr0.103Mn0.464Ni0.356O2的晶體結(jié)構(gòu)及電化學(xué)性能的影響。研究發(fā)現(xiàn),1%Co摻雜的樣品在小倍率下放電比容量略有提高。在0.1C和0.2C放電比容量分別達(dá)192.1m Ah/g、160.2m Ah/g;大倍率下循環(huán)穩(wěn)定性顯著提高,在0.5C和1.0C下,循環(huán)10次后,容量保持率分別為98.7%、102.0%。Al摻雜并沒(méi)有改善材料的容量,但2%Al的摻雜的樣品在0.5C下的穩(wěn)定性能有了顯著的提高。對(duì)Li1.016Cr0.103Mn0.464Ni0.356O2進(jìn)行Al2O3和Mg O包覆研究。包覆量分別為1%、2%、3%、4%,其中,4%Al2O3包覆的材料在小倍率下其放電比容量雖然較純樣要低,但其0.5C和1C下放電容量定均比純樣要好,0.5C和1C放電容量分別為115.1m Ah/g和95.1m Ah/g。1%Mg O包覆的材料在大倍率下的放電容量均比純樣高,其在0.5C和1C放電容量分別為113.2和100.2m Ah/g。
[Abstract]:In this paper, five ternary lithium-rich Li-Ni-Mn-Cr-O cathode materials were synthesized by sol-gel method using the system of Li [Li1/3Mn2/3] O2-LiCrO2-Li Ni1/2Mn1/2O2. The effects of molar ratio of Cr and mn Ni (Cr/Mn Ni = 0.38U 0.38U 0.29 0.21 / 0.15) and washing on the structure and electrochemical properties of the materials were studied, and the better materials were selected. Then the optimum conditions were optimized and the reaction temperature was investigated in detail. Effects of solvents, ratio of citric acid to transition metal, calcination temperature and calcination time on the electrochemical properties of the materials, Finally, the doping and coating of the material were studied. The surface morphology of the material was characterized by XRD and the element content was determined by XRD. The electrochemical performance was analyzed by constant current charge-discharge test. The molar ratio of metal to citric acid is 1: 1, and the precursor of Agne series is synthesized at 55 鈩，

本文編號(hào)：1574420