摘要
采用氢氧化物共沉淀法合成LiNi0.8Co0.1Mn0.1O2正极材料,对产物进行X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及电化学性能分析,结果表明,LiNi0.8Co0.1Mn0.1O2在0.5C下的循环性能和倍率性能较差,100次循环后,Li+的嵌入/脱嵌的界面阻抗(Rf)和电荷转移阻抗(Rct)迅速增加,极化增大。为改善其电化学性能,以尿素为沉淀剂,采用均匀沉淀法,在LiNi0.8Co0.1Mn0.1O2表面包覆不同比例Al2O3包覆层,研究其对LiNi0.8-Co0.1Mn0.1O2电化学性能的影响。在所有的样品中,1%Al2O3包覆LiNi0.8Co0.1Mn0.1O2具有最优的六方晶型α-NaFeO2层状结构和最低的阳离子混排度。SEM和TEM图表明无定形透明多孔Al2O3包覆层均匀地包覆在LiNi0.8Co0.1Mn0.1O2表面。与纯相相比,1%Al2O3包覆LiNi0.8Co0.1Mn0.1O2具有较好的电化学性能,包括相对较高的首次放电容量189.56mAh·g-1、最高的首次库伦效率87.95%、较好的循环性能和倍率性能。循环伏安(CV)和电化学阻抗(EIS)结果表明,LiNi0.8Co0.1Mn0.1O2电化学性能得到提高是由于Al2O3包覆层可以抑制电解液与正极副反应的发生,从而减小循环过程中界面阻抗值和电荷转移阻抗值的增大。
The hydroxide co-precipitation method was employed to synthesize the LiNi0. 8 Co0. 1 Mr0.1O2 anode material in this work, the product was analyzed with XRD, SEM, TEM together with the evaluation on its electro- chemical performance, The results showed that LiNi0. 8 Co0. 1Mno. 1O2 exhibited poor cycle performance and rate capbili- ty when the current was 0.5C. The interface impedence （Rf） and the charge transfer resistance （Ret） on the surface of embedded and extracted Li＋ increased rapidly after 100 cycles, accompanying with the increment of polarization inten- sity. In order to improve its electrochemical performance, urea was adopted as the precipitator and homogeneous pre- cipitation method was employed in present study, the A12 O3 coating layer with different ratios was used to coat the surface of LiNi0. 8 Co0. 1 Mn0.1 O2, its effect on the electrochemical performance of LiNi0. 8 Co0. 1 Mn0. 1O2 was also investigated. Among all the samples, LiNio. 8 Coo. 1Mn0.1O2 coated with 1% A12 03 exhibited optimal hexagonal a-NaFeO2 stratified structure and lowest cation hybrid arrangement degree. The SEM and TEM images indicated that the surface of LiNi0. 8 Co0. 1 Mn0. 1 O2 was uniformly coated with amorphous, transparent and porous Al2O3 coating layer. LiNi0. 8- Co0.1Mn0. 102 coated with 1% Al2O3 possessed better electrochemical performance when compared with pure phase, including a relatively higher first discharge capacity of 189. 56 mAh . g- 1, a highest first coulomb efficiency of 87. 95 %, better cycle performance and rate capability. The CV and EIS results indicated that the enhancement of electrochemical performance of LiNio. 8 Co0. 1M0.1O2 can be attributed to the fact that the A12 O3 coating layer can suppress the side reaction between electrolyte and positive pole, which decreased the increment of interface impedence value and charge transfer resistance value during the cyclic process.
出处
《材料导报》
EI
CAS
CSCD
北大核心
2016年第8期6-12,共7页
Materials Reports
基金
国家自然科学基金(51472070)
作者简介
陈道明：男，1991年生，硕士生，研究方向为锂离子电池正极材料的合成与改性E-mail：740795039@qq．com
张大伟：通讯作者，男，博士，教授，主要从事锂离子动力电池及电池电极材料的研究E-mail：Zhangdw@ustc．cn
