Ni-Cu掺杂诱导制备两类截角八面体LiMn_(2)O_(4)材料及其电化学性能  

Preparation of two types of truncated octahedral LiMn_(2)O_(4) materials inducedby Ni-Cu doping and their electrochemical properties

作　　者：吉颖 李萌 郭昱娇 郭俊明 向明武 刘晓芳 JI Ying;LI Meng;GUO Yu-jiao;GUO Jun-ming;XIANG Ming-wu;LIU Xiao-fang(School of Chemistry and Environment,Key Laboratory of Green-Chemistry Materials in University of Yunnan Province,Yunnan Minzu University,Kunming 650500,China;Eco-Environment Monitoring Station of Wuhua Branch,Kunming Eco-Environment Bureau,Kunming 650031,China)

机构地区：[1]云南民族大学化学与环境学院,云南省高校绿色化学材料重点实验室,云南昆明650500 [2]昆明市生态环境局五华分局生态环境监测站,云南昆明650031

出　　处：《材料热处理学报》2023年第3期28-40,共13页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51972282,U1602273)。

摘　　要：结合元素掺杂和晶面调控策略制备了同时包含(111)、(110)和(100)三个晶面和包含(111)和(100)两个晶面的两类截角八面体形貌的LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)正极材料,并研究了其电化学性能。结果表明:Ni-Cu共掺杂有效抑制了尖晶石LiMn_(2)O_(4)的Jahn-Teller效应,促进了其晶体发育和晶面的择优生长,但部分晶面发育较不完善,与一般情况不同的是Ni-Cu共掺后LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)正极材料的颗粒粒径显著增大;形成的截角八面体形貌中高暴露(111)面降低了Mn的溶解,少部分(110)和(100)晶面增加了Li^(+)的扩散通道。恒电流充放电测试结果表明:在5 C和10 C倍率下,LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)样品的首次放电容量分别为107.4和98.2 mAh/g,循环1000次,其容量保持率分别为72.5%和76.3%。而LiNi_(0.03)Mn_(1.97)O_(4)在相同的电流密度下其首次放电比容量为99.5和72.7 mAh/g,容量保持率为67.2%和73.2%。甚至在20 C下,LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)样品1000次循环后容量保持率高达89.3%。循环伏安和电化学阻抗测试表明:LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)材料有较高的Li^(+)的传输速率和较低的锂离子脱/嵌能垒。Two truncated octahedral LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)cathode materials with three crystal planes of(111),(110),(100)and two crystal planes of(111),(100)were prepared by combining element doping with crystal plane regulation strategy,and their electrochemical properties were studied.The results show that Ni-Cu co-doping effectively inhibits the Jahn-Teller effect of spinel LiMn_(2)O_(4),and promotes its crystal development and preferred growth of crystal planes.However,some crystal planes are not well developed.Different from the general situation,the particle size of the LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)cathode material significantly increases after Ni-Cu co-doping.The highly exposed(111)planes in the truncated octahedron morphology reduce the dissolution of Mn,and a few(110)and(100)crystal planes increase the diffusion channel of Li^(+).The results of Galvanostatic charge-discharge test show that the initial discharge capacity of the LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)sample is 107.4 and 98.2 mAh/g respectively at 5 C and 10 C,and the capacity retention rate is 72.5%and 76.3%respectively after 1000 cycles.The initial discharge capacities of the LiNi_(0.03)Mn_(1.97)O_(4)at the same current density are 99.5 and 72.7 mAh/g,and the capacity retention rates are 67.2%and 73.2%.Even at 20 C,the capacity retention rate of the LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)sample after 1000 cycles is as high as 89.3%.Cyclic voltammetry and electrochemical impedance spectroscopy measurements show that the LiNi_(0.03)Cu_(0.06)Mn_(1.91)O_(4)material has a higher Li^(+)ions transport rate and a lower lithium ion intercalation/de-intercalation barrier.

关 键 词：锂离子电池 正极材料 尖晶石型LiMn_(2)O_(4) Ni-Cu共掺 截角八面体 JAHN-TELLER效应 Mn溶解 

分 类 号：TM912[电气工程—电力电子与电力传动]