【摘要】：隨著科學(xué)技術(shù)的迅猛發(fā)展,鋰離子電池作為目前性能優(yōu)異的儲(chǔ)能方式之一,應(yīng)用范圍是越來(lái)越廣。在汽車(chē)行業(yè)應(yīng)用鋰離子電池是目前階段鋰離子電池發(fā)展的一個(gè)主要方向。這就要求鋰離子電池在能量密度,倍率性能和循環(huán)穩(wěn)定性都較好的情況下,同時(shí)具備成本低、安全性能好和與環(huán)境友好等優(yōu)點(diǎn)。然而,能滿(mǎn)足這些要求的鋰離子電池正極材料較少。最近,人們提出了一種具有層狀-層狀-尖晶石結(jié)構(gòu)的正極材料,得到較好的比容量和循環(huán)性能。為了進(jìn)一步改善電化學(xué)性能,又對(duì)該材料進(jìn)行了摻雜和包覆兩種改性。在本課題中,采用兩步溫度共沉淀法制備層狀-層狀-尖晶石固溶體正極材料δ[0.5Li2Mn O3·0.5Li Mn1/3Ni1/3Co1/3O2]·(1-δ)Li0.5Mn4/6Ni1/6Co1/6O2(也可以簡(jiǎn)寫(xiě)成Lix Mn4/6Ni1/6Co1/6Oy),并以此為基礎(chǔ)對(duì)該系材料進(jìn)行摻雜和包覆改性以求提升其電化學(xué)性能。實(shí)驗(yàn)結(jié)果確定T1=40℃,T2=80℃是兩步溫度共沉淀法制備正極材料較佳的一個(gè)工藝參數(shù)。摻雜改性實(shí)驗(yàn)選擇Li1.1Mn4/6Ni1/6Co1/6O2.30和Li1.2Mn4/6Ni1/6Co1/6O2.35材料進(jìn)行F-摻雜改性,對(duì)比后性能得出摻雜量為0.05為最佳。Li1.1Mn4/6Ni1/6Co1/6O2.25F0.05和Li1.2Mn4/6Ni1/6Co1/6O2.30F0.05材料較未改性材料在0.5 C倍率循環(huán)50次的容量保持率提高了8%左右;5 C倍率下的放電比容量與未改性前的材料相比有10~20 m A·h/g幅度的提高。對(duì)所制備出的正極材料Li1.1Mn4/6Ni1/6Co1/6O2.30、Li1.2Mn4/6Ni1/6Co1/6O2.35和Li1.3Mn4/6Ni1/6Co1/6O2.40進(jìn)行Al F3改性,Al F3的包覆量為1 wt%、2 wt%和3 wt%。包覆改性后材料的電化學(xué)性能有所改善,但是2 wt%的包覆效果更好;在0.5 C倍率下經(jīng)過(guò)循環(huán)50次后,材料的容量保持率提高10%左右;倍率性能也得到了改性,提高幅度在20 m A·h/g左右。
[Abstract]:With the rapid development of science and technology, lithium-ion batteries are widely used as one of the excellent energy storage methods. The application of lithium ion battery in automobile industry is one of the main directions in the development of lithium ion battery at present. This requires that lithium-ion batteries have the advantages of low cost, good safety and environmental friendliness under the condition of good energy density, rate performance and cycle stability. However, there are fewer cathode materials for lithium ion batteries to meet these requirements. Recently, a kind of layered spinel structure cathode material has been proposed to obtain better specific capacity and cycling performance. In order to further improve the electrochemical performance, the material was modified by doping and coating. In this paper, the layered spinel cathode material 未 [0.5Li2Mn O3 0.5Li Mn1/3Ni1/3Co1/3O2] (1- 未) Li0.5Mn4/6Ni1/6Co1/6O2 (also can be abbreviated as Lix Mn4/6Ni1/6Co1/6Oy) was prepared by two-step temperature co-precipitation method. The experimental results show that 40 鈩，

本文編號(hào)：2229692