本文關(guān)鍵詞： Li_(1.2)Ni_(0.2)Mn_(0.6)O_2 鋰離子電池 正極材料 摻雜 包覆　出處：《深圳大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著無人機、智能眼鏡、VR等新型的電子產(chǎn)品不斷問世,對電池的安全性、放電比容量、充放電次數(shù)等要求越來越高。富鋰Li_(1.2)Ni_(0.2)Mn_(0.6)O_2正極材料具有高放電比容量而受到越來越多的關(guān)注。但該材料存在大倍率性能較差、循環(huán)穩(wěn)定性不好等缺點。本文采用壓力式噴霧干燥法來合成Li_(1.2)Ni_(0.2)Mn_(0.6)O_2,并通過元素摻雜和表面包覆提高材料大倍率性能和循環(huán)穩(wěn)定性。具體內(nèi)容如下:1、通過壓力式噴霧干燥法優(yōu)化不同條件來合成Li_(1.2)Ni_(0.2)Mn_(0.6)O_2。通過調(diào)節(jié)不同配鋰量、設(shè)備的進風溫度、壓力等因素,研究其對所制備材料晶體結(jié)構(gòu)和電化學(xué)性能等的影響。實驗結(jié)果顯示:以Li OH、Li2CO3、LiNO3為鋰源來制備Li_(1.2)Ni_(0.2)Mn_(0.6)O_2,50次充放電循環(huán)后,LiOH為鋰源時的容量最高。其次當配鋰量為1.00 mol(化學(xué)計量比)、進風溫度為170℃時,材料的綜合性能最好。通過調(diào)節(jié)噴霧器的壓力得到納米結(jié)構(gòu)的Li_(1.2)Ni_(0.2)Mn_(0.6)O_2材料。當噴霧壓力為0.6 MPa時,樣品粒徑均在150~200 nm之間,在2.5~4.8 V、1 C倍率下循環(huán)50次放電容量為153.4 mAh/g。在優(yōu)化以上反應(yīng)條件下合成Li_(1.2)Ni_(0.2)Mn_(0.6)O_2的電化學(xué)性能優(yōu)良。2.5~4.8 V電壓范圍內(nèi)充放電,0.1 C條件下50次后放電容量為227 mAh/g;1 C條件下100次后放電容量為160.1 mAh/g。當充放電電壓范圍擴大到2.0~4.8 V時,0.1 C條件下50次后放電容量為231.4 mAh/g;1 C條件下100次后放電容量為166.4 mAh/g。2、通過微量的Co摻雜替代部分的Ni和Mn,來改善Li_(1.2)Ni_(0.2)Mn_(0.6)O_2在循環(huán)過程中結(jié)構(gòu)的穩(wěn)定性。Co摻雜Li1.2Ni0.2-x/2Mn0.6-x/2CoxO_2在一定程度下可降低Li+/Ni~(2+)混排。隨著Co摻雜量的增加,材料的結(jié)晶度也隨之增高。所有樣品均為層狀結(jié)構(gòu),并且六方層狀結(jié)構(gòu)越好,鋰離子就更容易脫嵌。當摻雜量為0.06時,材料的循環(huán)穩(wěn)定性最好。2.0~4.8 V電壓范圍內(nèi),0.1 C時50次后放電容量256.1mAh/g,容量保持率為92.4%;1 C時100次后放電容量179 mAh/g。3、通過不同質(zhì)量的Al_2O_3包覆Li_(1.2)Ni_(0.2)Mn_(0.6)O_2可以有效地避免材料與電解液的接觸,減少了電解液與材料之間的副反應(yīng)。當包覆量為3wt.%時,2.0~4.8 V電壓范圍內(nèi)0.1 C時50周后放電容量為263 mAh/g,容量保持率為89.5%。1 C時100周循環(huán)后容量為185.5 mAh/g。通過LPAN包覆、摻雜Li_(1.2)Ni_(0.2)Mn_(0.6)O_2樣品。LPAN在高溫下形成一種網(wǎng)狀類石墨烯結(jié)構(gòu),降低了材料的表面電阻,使材料在高電壓條件下的循環(huán)穩(wěn)定性得到提升和放電比容量得到增加。當包覆量為20wt.%時,2.0~4.8 V電壓范圍內(nèi)0.1C 50次循環(huán)后放電容量為262.5 mAh/g,容量保持率為98.3%;1 C倍率下100次循環(huán)后的放電容量為177.5 mAh/g。LPAN包覆、摻雜樣品時不僅可以避免材料與電解液的直接接觸,并且在更大的電壓范圍內(nèi)充放電,LPAN包覆、摻雜時對材料的結(jié)構(gòu)穩(wěn)定性起著巨大作用。當包覆量為20wt.%時在1.5~4.8 V電壓范圍內(nèi),0.1 C充放電循環(huán)50次后放電容量為290.5 mAh/g,容量保持率為85.8%。
[Abstract]:With the advent of new electronic products such as UAV, smart glasses, VR and so on, the safety of batteries, discharge specific capacity, More and more attention is paid to the charge / discharge times of lithium-rich Li_(1.2)Ni_(0.2)Mn_(0.6)O_2 cathode material due to its high discharge specific capacity. In this paper, we use pressure-type spray drying method to synthesize Liasco _ 1.2Nii _ (0.2) MN _ (0.6) O _ (2), and improve material's large ratio performance and cycle stability by element doping and surface coating. The content is as follows: 1: 1, through pressure-type spray drying. The dry method optimizes the different conditions for the synthesis of Listav 1.2Nitig 0.2mn.o.2.By adjusting the different lithium-containing amounts, Air inlet temperature, pressure and other factors of the equipment, The experimental results show that LiOH Li 2CO 3O 3 LiNo3 is used as lithium source to prepare Lio 1. 2 Nitix 0. 2S / O 0. 2. The capacity of LiOH is the highest after 50 charge / discharge cycles. Secondly, when the lithium content is 1. 00 mol (chemical), the lithium content is 1. 00 mol / L (chemical = 1. 00 mol) after 50 charge / discharge cycles, when the LiOH is used as the lithium source, the experimental results show that the capacity of the prepared material is the highest when the lithium content is 1. 00 mol / L (chemical). When the inlet air temperature is 170 鈩，

本文編號：1550084