摘要
Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.
富锂锰基材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)以其优异的放电比容量和低廉的成本成为锂离子电池正极材料的研究热点。然而,富锂锰基材料存在循环性能和倍率性能差的不足,限制了其商业化的应用。快离子导体因其具有较好的稳定性和较高的锂离子传导速率等特点,被广泛用于正极材料的包覆研究。本研究采用溶胶凝胶法合成了Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_3(LATP)快离子导体,并对Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)正极材料颗粒表面进行包覆改性。电化学测试结果表明,LRNCM@LATP1样品在0.2C条件下循环100次仍有198 mA·h/g的放电比容量,容量保持率达到81%,相较未包覆的P-LRNCM(放电比容量188.4 mA·h/g,容量保持率76%)表现出更优异的循环性能。离子扩散速率(D_(Li+))是影响材料倍率性能的重要因素,包覆1%LATP的LRNCM材料(LRNCM@LATP1)在100次循环后,D_(Li+)从包覆前的4.94×10^(-13) cm^(2)/s提高到包覆后的5.68×10^(-12) cm^(2)/s,材料界面的离子传输能力得到了改善,LRNCM@LATP1在5C放电条件下的比容量可以达到102.5 mA·h/g,高倍率性能得到提升。因而,LATP的包覆改性可有效提高Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)的电化学性能,对锂离子正极材料的研究具有重要的意义。
作者
LAI Xiang-wan
HU Guo-rong
PENG Zhong-dong
CAO Yan-bing
DU Ke
LIU Ye-xiang
来湘皖;胡国荣;彭忠东;曹雁冰;杜柯;刘业翔(School of Metallurgy and Environment,Central South University,Changsha 410083,China;Engineering Research Center of the Ministry of Education for Advanced Battery Materials,Central South University,Changsha 410083,China;Hunan Provincial Key Laboratory of Nonferrous Value-Added Metallurgy,Central South University,Changsha 410083,China)
基金
Project(51772333) supported by the National Natural Science Foundation of China。
