摘要
采用水热法制备了掺杂稀土Ce的LiFe_(1-x)Ce_xPO_4/C(x=0,0.01,0.03,0.05)正极材料,并通过一系列系统的测试对所制备材料进行电化学性能研究。XRD图谱表明,掺杂稀土1%~5%Ce(摩尔分数)未改变LiFePO_4的橄榄石型晶体结构,但扩大了晶胞体积,有利于Li^+的脱嵌。SEM分析结果进一步表明,稀土Ce的掺杂具有细化晶粒的作用,可有效缩短Li^+的扩散和迁移途径。在2.0~4.0V电位范围内,随着稀土Ce掺杂量的增加,0.1C倍率下的LiFe_(1-x)Ce_xPO_4/C初始放电比容量先升高后下降,在x=0.03时达到最高,放电比容量为144.1mA·h/g,比未掺杂Ce的提高17.4%,且其循环50次后容量保持率为95.0%。EIS和CV测试结果表明,LiFe_(1-x)Ce_xPO_4/C(x=0.03)具有最低的电荷迁移电阻,且样品在0.1C倍率下循环50次后氧化还原峰明显,说明样品结构稳定,可逆反应特性良好。
. LiFe1-xCex PO4/C （x= 0,0. 01,0. 03,0. 05） cathode material doped with rare earth Ce was syn- thesized with hydrothermal method. The electrochemical properties of the prepared material were studied by a series of systematic tests. XRD results show that the olivine crystal structure of LiFePO4 stays the same after doping 1 %- 5 % Ce, but cell volume is extended, which is favorable for the Li＋ extraction-inser- tion. The SEM images further demonstrate that doping rare earth Ce can refine the grain size,and then ef- fectively reduce Li＋ diffusion and migration pathway. In the potential range of 2. 044.0 V,the initial dis- charge specific capacity of LiFe1-xCexPO4/C at the discharge rate of 0.1C firstly increases and then decrea- ses with Ce dosage increasing,and it reaches the maximum value of 144.1 mA /g at x= 0. 03 , increased by 17.4% compared with the undoped LiFePO4/C. And its capacity retention ratio is 95.0% after 50 cy- cles. CV and EIS measurements show that LiFe1-xCexPO4/C （x=0.03） has the lowest charge transfer re- sistance,and the redox peak of the sample remains visible after 50 cycles at the charge and discharge rate of 0.1C,demonstrating that the sample has stable structure and good reversible reaction performance.
作者
张阳
王娟
王亮亮
许云华
ZHANG Yang WANG Juan WANG Liang-liang XU Yun-hua(School of Mechanical and Electrical Engineering,Xi＇an University of Architecture and Technology, Xi＇an 710055 ,China Shaanxi Key Laboratory of Nano Materials and Technology,Xi＇an 710055 ,China)
出处
《稀有金属与硬质合金》
CSCD
北大核心
2017年第4期42-46,61,共6页
Rare Metals and Cemented Carbides
基金
国家自然科学基金(51202179)
教育部科学技术研究重点项目(212174)
陕西省自然科学基金(2013KJXX-57)
陕西省教育厅自然科学基金(11JK0826
12JS060)
国家国际科技合作专项(2015DFR50350)
金川-西安建筑科技大学预研究项目(X06071)
