磷酸铁锂/小尺寸石墨烯复合锂离子电池阴极材料的制备及储能特性  

Preparation and Energy Storage Performance of LiFPOe/Small-Size Graphene Composites as Cathode Material for the Lithium-Ion Battery

作　　者：夏童 李刚 徐世伟 赵洋 胡南滔 Xia Tong;Li Gang;Xu Shiwei;Zhao Yang;Hu Nantao(Key Laboratory of Thin Film and Micro Technology of Ministry of Education,School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Key Laboratory of Artificial Structures and Quantum Control,School of Physics and Astronomy,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学电子信息与电气工程学院,薄膜与微细技术教育部重点实验室,上海200240 [2]上海交通大学物理与天文学院,人工结构与量子控制重点实验室,上海200240

出　　处：《微纳电子技术》2021年第5期386-391,共6页Micronanoelectronic Technology

基　　金：上海市自然科学基金资助项目(17ZR1414100)。

摘　　要：磷酸铁锂(LiFePO4,LFP)是一种良好的阴极材料,然而导电率低和锂离子扩散系数小的缺点限制了其在高倍率下的电化学性能。寻找规模化工艺制备高倍率的锂离子电池阴极材料,对于高倍率锂离子电池的制备和应用意义重大。采用模板刻蚀法制备尺寸小于200 nm的小尺寸氧化石墨烯(SGO),用湿法球磨和高温固相法有效地制备碳包覆的磷酸铁锂/小尺寸石墨烯(LFP@C/SGN)复合电极材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和电化学阻抗谱(EIS)对样品进行表征分析和电化学性能测试。测试结果表明,复合材料具有完整的晶型,SGN的引入有效地减小了LFP@C的颗粒尺寸并提升了材料的导电性。制备的LFP@C/SGN复合材料具有优异的倍率性能,在10 C(1 C=170 mA/g)的电流密度下,电极的放电比容量仍可以保持在92.6 mA·h/g。此外,在15 C的电流密度下,循环100次后仍具有75.8 mA·h/g的放电比容量。实验结果表明SGN的引入能有效提高电导率与离子扩散速率,从而有效地提升电池的倍率性能。Lithium iron phosphate(LiFPOe4,LFP) as a cathode material performs well. However, its electrochemical performance at high rate is hindered by low conductivity and small lithium-ion diffusion coefficient. Looking for a process to prepare high-rate lithium-ion battery cathode materials in large scale is of great importance for the preparation and application of the high-rate lithium-ion battery. The template etching method was used to prepare small-size graphene oxide(SGO) with the size smaller than 200 nm. The wet ball milling method and high temperature solid phase method were used to effectively prepare the carbon-coated lithium iron phosphate/small-size graphene(LFP@C/SGN) composite electrode material with small-size. The X-ray diffractometer(XRD), scanning electron microscope(SEM) and electrochemical impedance spectrum(EIS) were used for characterization analysis and electrochemical test of the samples. The test results show that the composite material has a complete crystal formation, and the introduction of SGN effectively reduces the particle size of LFP@C and improves the conductivity. The prepared LFP@C/SGN composite material has excellent rate performance. At a current density of 10 C(1 C=170 m A/g), the discharge specific capacity of the electrode can still be maintained at 92.6 mA·h/g. In addition, at a current density of 15 C, the discharge specific capacity is 75.8 mA·h/g after 100 cycles. The experimental results show that the introduction of SGN can effectively improve the conductivity and ion diffusion rate, thereby effectively improving the rate performance of the battery.

关 键 词：小尺寸石墨烯 锂离子电池 磷酸铁锂(LFP) 高温固相法 阴极材料 复合材料 

分 类 号：TM912.9[电气工程—电力电子与电力传动]