化学学报 ›› 2016, Vol. 74 ›› Issue (2): 185-190.DOI: 10.6023/A15100658 上一篇    下一篇

研究论文

锗酸锌纳米棒@石墨烯复合负极材料的制备及储锂性质

童震坤, 方姗, 郑浩, 张校刚   

  1. 江苏省能量转换材料与技术重点实验室 南京航空航天大学材料科学与技术学院 南京 211106
  • 收稿日期:2015-10-14 出版日期:2016-02-15 发布日期:2016-01-29
  • 通讯作者: 张校刚 E-mail:azhangxg@nuaa.edu.cn
  • 基金资助:

    项目受国家重点基础研究发展计划(973项目)(No.2014CB239701)、国家自然科学基金(Nos.21173120,51372116)、江苏省自然科学基金(BK2011030)和中央高校基本科研业务费专项资金(NP2014403,NJ20140004)和江苏高校优势学科建设工程项目资助.

Zn2GeO4 Nanorods@Graphene Composite as Anode Materials for Li-ion Batteries

Tong Zhenkun, Fang Shan, Zheng Hao, Zhang Xiaogang   

  1. Jiangsu Key Laboratory of Materials and Technology for Energy Conversion, College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211106
  • Received:2015-10-14 Online:2016-02-15 Published:2016-01-29
  • Supported by:

    Project supported by the National Basic Research Program of China (973 Program) (No. 2014CB239701), the National Natural Science Foundation of China (Nos. 21173120, 51372116), the Natural Science Foundation of Jiangsu Province (BK2011030), the Fundamental Research Funds for the Central Universities of NUAA (NP2014403, NJ20140004) and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.

以二氧化锗和二水合醋酸锌为原料,采用水热法制备了锗酸锌纳米棒,并将其与氧化石墨烯复合,制备了石墨烯包覆的锗酸锌纳米棒三维复合材料. SEM等测试表明,锗酸锌纳米棒均匀地穿插在石墨烯片中,阻止了石墨烯片之间相互堆垛,而石墨烯片层之间相互连接,形成三维的空间导电网络,提高了材料的电子导电性.电化学测试表明,石墨烯片作为稳定的框架,能够有效缓冲活性物质在脱嵌锂过程中产生的体积变化,在500 mA·g-1电流密度下循环190次后, Zn2GeO4@RGO复合材料的嵌锂容量仍有1189.5 mAh·g-1;在3.2 A·g-1的大电流密度下,嵌锂容量达到449.5mAh·g-1,表明该复合材料具有优异的长循环稳定性和良好的倍率性能.

关键词: 锂离子电池, 负极材料, 锗酸锌纳米棒, 还原氧化石墨烯, 水热法

Commercial graphite anode material for lithium-ion batteries (LIB) with a theoretical specific capacity of 372 mAh·g-1 is unable to satisfy the requirements of increasing mobility and high energy demands. Therefore, it is necessary to develop alternative anode material with high specific capacity. In recent years, a large amount of research has been worked out in the area of high capacity anode materials, for example, silicon (Si) and germanium (Ge). However, the large volume changes of Si and Ge during the charge and discharge process result in the cracking and pulverization of active material and delamination from the current collector, leading to a rapid decay during the cycling. As a semiconductor, Zn2GeO4 possesses a high capacity of 1443 mAh·g-1 which is 90.19% as high as Ge. Nevertheless, the weight rate of germanium element in Zn2GeO4 is only 27.15%, which can effectively cut down the cost of anode material. In this work, Zn2GeO4 nanorods were synthesized through a hydrothermal method by using GeO2 and Zn(CH3COO)2·2H2O and combined with RGO to form a 3D composite. In a typical synthesis, 1.10 g Zn(CH3COO)2·2H2O and 0.52 g GeO2 was added into 15 mL deionized (DI) water and the pH of the mixture was adjusted to 7~8 by using NaOH aqueous solution. Then, the hydrothermal treatment was performed at 140℃ for 24 h in an oven to obtain Zn2GeO4 nanorods. Finally, the Zn2GeO4 nanorods were filtrated with GO to form a uniform membrane and reduced by hydrazine hydrate. The Zn2GeO4 nanorods and Zn2GeO4@RGO composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, etc. SEM and TEM testified that Zn2GeO4 nanorods were firmly adhered on the surface of graphene sheets, which can effectively avoid the stacking of graphene sheets. The graphene sheets connected with each other to form an electric conductive network, which can improve the electrical conductivity of the composite. Furthermore, the electrodes are fabricated without conductive additive that can improve the weight ratio of the active material in the whole electrodes. The excellent electrochemical performance showed that the 3D architecture electrode which worked as a stable framework to accommodate the volume change of active material during Li+insertion/extraction. It delivers a specific capacity of 1189.5 mAh·g-1 at 500 mA·g-1 after 190 discharge/charge cycles. When at different current densities of 0.8, 1.6, 3.2 A·g-1, the capacities were found to be about 880, 700, 450 mAh·g-1, respectively. Even at a high current density of 6.4 A·g-1, the capacity can maintain about 250 mAh·g-1. These results indicate that the composite possesses outstanding cycling stability and excellent rate performance.

Key words: lithium-ion batteries, anode materials, zinc germanate nanorod, reduced graphene oxide, hydrothermal method