储能科学与技术 ›› 2020, Vol. 9 ›› Issue (4): 1044-1051.doi: 10.19799/j.cnki.2095-4239.2020.0099

• 储能材料与器件 • 上一篇    下一篇

冷冻干燥辅助合成MnO/还原氧化石墨烯复合物及其电化学性能

马腾飞1,2(), 马超2, 孙瑞2, 季红梅2(), 杨刚1,2()   

  1. 1.苏州大学机电工程学院，江苏 苏州 215006
    2.常熟理工学院苏州功能陶瓷材料重点实验室，江苏 常熟 215500
  • 收稿日期:2020-03-09 修回日期:2020-04-01 出版日期:2020-07-05 发布日期:2020-06-30
  • 通讯作者: 季红梅,杨刚 E-mail:1473234316@qq.com;jhm@cslg.edu.cn;gyang@cslg.edu.cn
  • 作者简介:马腾飞（1993—），男，硕士研究生，研究方向为能源材料，E-mail：1473234316@qq.com
  • 基金资助:
    国家自然科学基金项目(51802030)

Freeze-drying assisted synthesis of mno/reduced graphene composite and the improved rate cyclic performance for lithium ion batteries

MA"Tengfei1,2(), MA"Chao2, SUN"Rui2, JI"Hongmei2(), YANG"Gang1,2()   

  1. 1.School of Mechanical and Electrical Engineering, Soochow University, Suzhou 215006, Jiangsu, China
    2.Suzhou Key Laboratory of Functional Ceramic Materials, Changshu Institute of Technology, Changshu 215500, Jiangsu, China
  • Received:2020-03-09 Revised:2020-04-01 Online:2020-07-05 Published:2020-06-30
  • Contact: Hongmei JI,Gang YANG E-mail:1473234316@qq.com;jhm@cslg.edu.cn;gyang@cslg.edu.cn

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摘要：

锰氧化物具有理论比容量高、资源丰富、绿色环保等优势，可替代锂离子电池传统负极材料——石墨作为下一代锂离子电池负极材料。但是锰氧化物体积效应严重，在充放电循环过程中会出现严重的粉化和团聚现象。综合氧化锰的高比容量和石墨烯的高导电率优势，本工作采用冷冻干燥辅助水热合成的方法制备了氧化锰/还原氧化石墨烯复合物（MnO/rGO）。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等表征方法和电化学测试，表征了MnO/rGO复合物的结构、形貌和电化学性能。结果表明，冷冻干燥辅助水热合成制备的MnO/rGO复合物，MnO纳米颗粒均匀地分布于石墨烯片层。两者均匀的复合结构有利于抑制充放电过程中MnO粉化现象，同时为锂离子的传递提供通道。MnO/rGO复合物在0.1 A/g的电流密度下循环179圈后，放电比容量依然高达1066.2 mA·h/g，在5 A/g的电流密度下循环120圈后放电比容量为504.3 mA·h/g。rGO不仅提高了复合材料的导电性，同时抑制了MnO的体积效应。采用鼓风干燥辅助法、水热合成的对比样品则出现了明显的团聚现象，比容量低、倍率性能较差。冷冻干燥辅助法能够制备过渡金属氧化物纳米颗粒充分分散于还原石墨烯结构的复合材料，两者复合结构能够提供优良的电化学性能。

关键词: 锂离子电池, 负极材料, 氧化锰/还原石墨烯, 冷冻干燥, 电化学性能

Abstract:

Taking advantage of manganese oxide (MnO) with high specific capacity and graphene with high conductivity, the composite of MnO/rGO has been synthesized by using freeze-drying assisted hydrothermal method. The structure, morphology and electrochemical performance of MnO/rGO composite are characterized by X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical tests. MnO nanoparticles in MnO/rGO composite are homogeneously dispersed on and wrapped by rGO nanosheets which is helpful in improving the stability and conductivity of MnO during charging/discharging cycles. MnO/rGO delivers specific capacity of 870.4 mA·h/g after 100 cycles at a current density of 0.1 A/g, and it delivers 178.2 mA·h/g after 100 cycles at a current density of 15 A/g. rGO not only improves the conductivity of the composite and suppresses the volume effect of MnO during cycles. The comparison sample prepared by traditional drying assisted hydrothermal synthesis shows obvious agglomeration, lower discharge capacity and worse rate performance. Freeze drying-assisted hydrothermal synthesis method will be potential in synthesizing homogeneous composites of transitional metal oxides/rGO as high performance anode materials for lithium ion batteries.

Key words: lithium ion batteries, anode materials, manganese oxide/reduced graphene, freeze-drying, electrochemical performance

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