ZnF_2包覆对锂离子电池正极材料LiNi_(0.5)Mn_(1.5)O_4性能的影响  

Effect of ZnF_2 Coating on Performance of LiNi_(0.5)Mn_(1.5)O_4 Cathode Material for Lithium-ion Batteries

作　　者：谢迪志 杨建文[1] 陈权启[1] 李延伟[1] 张灵志[1,2] 

机构地区：[1]桂林理工大学广西有色金属隐伏矿床勘查及材料开发协同创新中心,广西桂林541000 [2]中国科学院广州能源研究所,广东广州510640

出　　处：《精细化工》2017年第3期279-284,340,共7页Fine Chemicals

基　　金：国家自然科学基金项目(51164006);广西有色金属隐伏矿床勘查及材料开发协同创新项目(GXYSXTZX2016-P-2);广西科学研究与技术开发计划项目(桂科能1298025-9)~~

摘　　要：采用溶胶-凝胶法制备了LiNi_(0.5)Mn_(1.5)O_4正极材料,并利用Zn F2对其表面进行包覆改性。XRD、SEM和TEM测试表明,包覆处理不影响材料的晶体结构,2%(质量分数,以LiNi_(0.5)Mn_(1.5)O_4质量计,下同)的Zn F2在LiNi_(0.5)Mn_(1.5)O_4表面形成了约7 nm厚均匀包覆层。对未包覆的LiNi_(0.5)Mn_(1.5)O_4和1%、2%、3%的Zn F2包覆后的LiNi_(0.5)Mn_(1.5)O_4的电化学性能进行了考察,发现Zn F2包覆能够减弱电解液与LiNi_(0.5)Mn_(1.5)O_4正极材料之间的相互作用,稳定电极表面,提高材料的电化学性能。其中,2%Zn F2包覆样品表现出最佳的循环性能和倍率性能,0.2C电流倍率下循环200圈后,其放电比容量维持在109.0 m A·h/g,保持率为79.7%;5 C电流倍率下循环500圈后,放电比容量维持在94.2 m A·h/g,保持率为85.6%。LiNi0.5Mn1.5O4 cathode material was prepared by a sol-gel method,and subsequently coated with ZnF2 as a buffering layer. The obtained products were characterized by XRD,SEM and TEM. The results show that the treatment of ZnF2 coating does not change the structure of LiNi0.5Mn1.5O4. The LiNi0.5Mn1.5O4 coated with 2% ZnF_2（ based on mass of LiNi0.5Mn1.5O4 results in the formation of a homogeneous ZnF2 layer of about 7 nm in thickness. The electrochemical performances of the pristine LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4 with various amount of ZnF2（ 1%,2%,and 3%） were investigated. It is found that coated ZnF2 can weaken the interaction between the electrolyte and LiNi0.5Mn1.5O4 and remarkably stabilize the electrode surface,thus improving the electrochemical performances of LiNi0.5Mn1.5O4. As a result,LiNi0.5Mn1.5O4 with an optimized coating of 2% ZnF2 exhibits the best electrochemical cycling stability and rate performance. The discharge capacity of the sample reaches up to109. 0 m A · h / g with 79. 7% capacity retention at 0. 2 C after 200 cycles. In addition,that is 94. 2m A·h / g and remains 85. 6% of its initial discharge capacity after 500 cycles at 5 C.

关 键 词：LINI0.5MN1.5O4 高电位正极材料 ZnF2 包覆 电化学性能 

分 类 号：O646.21[理学—物理化学]