本文關(guān)鍵詞：鋰離子電池高錳三元正極材料的富鋰化研究　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

  更多相關(guān)文章： 富鋰正極材料 鋰離子電池 預(yù)循環(huán)處理 MgO包覆 鈉添加

【摘要】：本文研究高錳三元正極材料x Li2Mn O3·(1-x)Li Ni0.2Co0.2Mn0.6O2的富鋰化,考察富鋰量、合成方法、合成條件、預(yù)循環(huán)處理以及包覆和摻雜等改性方法對材料電化學(xué)性能的影響。采用XRD表征材料的晶體結(jié)構(gòu),采用SEM表征材料的形貌,采用恒流充放電測試、CV、EIS表征材料的電化學(xué)性能�？疾觳煌讳嚵�,即x值(0.7、0.6、0.5和0.4)對材料性能的影響。研究表明:當(dāng)x=0.5,即Li2Mn O3相和Li MO2相為1:1時得到的材料層狀結(jié)構(gòu)良好,陽離子混排程度較低,具有最高的比容量和最佳的循環(huán)穩(wěn)定性。采用高溫固相法,以過渡金屬乙酸鹽和Li2CO3為原料合成富鋰正極材料0.5Li2Mn O3·0.5Li Ni0.2Co0.2Mn0.6O2,考察了煅燒溫度(750、800、850、900℃)和煅燒時間(9、12、15、18 h)對材料性能的影響。800℃煅燒12 h得到的樣品具有良好的層狀結(jié)構(gòu);0.1 C充放電比容量分別為218、162.1 m Ah/g,庫倫效率為74.36%;0.1 C循環(huán)5次容量保留率為106.9%;0.2 C循環(huán)10次容量保留率為93.93%。低壓預(yù)循環(huán)處理能降低直接充電至高電位對材料結(jié)構(gòu)的破壞,改善其倍率性能;Mg O包覆層能夠抑制Li PF6分解產(chǎn)生的HF與電極材料反應(yīng),進(jìn)而降低金屬離子的溶解,改善材料的循環(huán)穩(wěn)定性,最佳包覆量為2 wt.%。采用碳酸鹽共沉淀法,以過渡金屬硫酸鹽溶液、Na2CO3溶液和氨水為起始反應(yīng)物合成碳酸鹽前驅(qū)體,考察了過渡金屬離子濃度(0.5、1.0、1.5、2.0 mol/L)和沉淀溶液p H值(8.0、8.5、9.0)對材料性能的影響。研究表明:過渡金屬鹽溶液濃度為1.0 mol/L、沉淀溶液p H為8.5時制得的前驅(qū)體經(jīng)混鋰和高溫煅燒后得到的樣品具有良好的層狀結(jié)構(gòu)和較低的Ni2+、Li+陽離子混排度;0.1 C下首次充放電比容量分別為350.9、280.7 m Ah/g,庫倫效率為79.99%;0.1 C循環(huán)5次容量保留率為91.92%;0.2 C循環(huán)10次容量保留率為99.71%。低壓預(yù)循環(huán)處理在一定程度上提高了材料的比容量及其倍率性能;Na元素添加在材料中形成Na0.7Mn O2.05結(jié)構(gòu)的新相,促進(jìn)了Li+在材料中的擴散,提高了材料的倍率和循環(huán)性能。性能最佳的樣品為Li1.11Na0.06Ni0.10Co0.10Mn0.63O2,2.0-4.8 V電壓范圍內(nèi)0.2 C首次充放電比容量分別為359.2、277.9 m Ah/g,庫倫效率為77.37%,0.5 C循環(huán)50次容量保留率為94.90%。
[Abstract]:In this paper, we studied the lithium enrichment of high manganese three pole cathode material x Li2Mn O3. (1-x) Li Ni0.2Co0.2Mn0.6O2. The effects of lithium content, synthesis method, synthesis conditions, pretreatment and coating and doping on the electrochemical properties of the material were investigated. The crystal structure of the material was characterized by XRD, and the morphology of the material was characterized by SEM. The electrochemical properties of the material were characterized by constant current charge discharge test, CV and EIS. The effects of different lithium content, namely x (0.7, 0.6, 0.5 and 0.4), on the properties of the materials were investigated. The research shows that when x=0.5, namely Li2Mn O3 phase and Li MO2 phase are 1:1, the material has good layered structure, low degree of cation mixing, and has the highest specific capacity and the best cycling stability. The lithium rich cathode material 0.5Li2Mn O3. 0.5Li Ni0.2Co0.2Mn0.6O2 was synthesized by using high-temperature solid phase method and transition metal acetate and Li2CO3 as raw material. The effects of calcination temperature (750, 800, 850, 900 degrees C) and calcination time (9, 12, 15, 18 h) on the properties of the material were investigated. The samples obtained by calcining 12 h at 800 degrees have good lamellar structure. The charge and discharge capacity of 0.1 C is 218 and 162.1 m Ah/g respectively, and the efficiency of Kulun is 74.36%. 0.1 C cycle 5 times capacity retention rate is 106.9%; 0.2 C cycle 10 time capacity retention rate is 10. Low pressure circulation treatment can decrease the damage of direct charging a high potential material structure, improve the rate performance; Mg O HF coated with electrode material Li PF6 decomposition can produce reaction inhibition layer, thereby reducing the dissolved metal ions, improving the cycling stability of materials, the best coating amount was 2 wt.%. Using co precipitation method, using transition metal sulfate solution, Na2CO3 solution and ammonia as the starting reactant synthesis of carbonate precursor, investigate the transition metal ion concentration (0.5, 1, 1.5, 2 mol/L) and P H precipitation solution (8, 8.5, 9) on the properties of materials. The research indicated that the transition metal salt solution concentration of 1 mol/L, P H as the precursor solution to precipitate 8.5 prepared by mixing lithium and calcined samples obtained with good layered structure and low Ni2+, Li+ cation mixing degree; 0.1 C the first charge discharge were 350.9, 280.7 m Ah/g the specific capacity, Kulun is 79.99%; 0.1 C 5 cycles the capacity retention rate was 91.92%; 0.2 C 10 cycles the capacity retention rate was 99.71%. Low pressure pre cycling treatment improves the specific capacity and rate performance of materials to a certain extent. Na element added to the material form a new phase of Na0.7Mn O2.05 structure, which promotes the diffusion of Li+ in materials, and improves the rate and cycle performance of materials. The best performance sample is Li1.11Na0.06Ni0.10Co0.10Mn0.63O2,2.0-4.8 V, which is 0.2 C within the voltage range. The first charge and discharge specific capacity is 359.2 and 277.9 m Ah/g, respectively. The efficiency of Kulun is 77.37%, 0.5 C cycle 50 times capacity retention rate is 94.90%.
【學(xué)位授予單位】：河北工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM912

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