MnO_2包覆的碳纳米管-硫复合正极材料的制备及性能  

Preparation and properties of manganese dioxide coated carbon nanotubes-sulfur composite cathode material

作　　者：尚永亮[1] 王诚文[1] 刘斌[1] 刘军[1,2] 柯曦[1,2] 刘丽英[1,2] 施志聪[1,2] 

机构地区：[1]广东工业大学材料与能源学院,广东广州510006 [2]广东省新能源材料与器件工程技术研究中心,广东广州510006

出　　处：《储能科学与技术》2017年第3期411-417,共7页Energy Storage Science and Technology

基　　金：国家自然科学基金(21673051;51604086);广东省科技厅公益研究项目(2014A010106029;2016A010104015);广州市科技计划项目产学研协同创新重大专项对外科技合作专题(201604030037;广东工业大学青年重点项目(252151038)

摘　　要：针对锂硫电池中单质硫导电性差和中间产物多硫化锂易溶解于电解液的问题,本文以多壁碳纳米管为导电骨架负载硫,再在其表面包覆一层MnO_2,制备了高性能MnO_2@MWCNT-S的复合材料。多壁碳纳米管可以提供电子导电路径,提高电极材料的导电性能,而表面的MnO_2对多硫化物有很强的化学吸附作用,可以抑制多硫化物的溶解,从而提高活性材料利用率。通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征,发现硫均匀负载在碳纳米管上,它们的表面包覆有一层MnO_2。经热重分析(TGA)测试,MnO_2@MWCNT-S复合材料中硫的含量为58.4%。电化学测试结果表明,MnO_2显著提高了电极材料的首次充放电比容量,并能有效地延缓多硫化物的溶解。MnO_2@MWCNT-S复合材料在0.1 C倍率下,首次充放电比容量达到1148.98 m A·h/g,100次充放电后容量依然保持在560.04 m A·h/g。The development of lithium-sulfur batteries has been hindered by the poor conductivity of sulfur and the dissolution of intermediate species （lithium polysulfides） into the electrolyte. In this study, MnO2@MWCNT-S was synthesized by impregnating multi-walled carbon nanotubes （MWCNT） with sulfur, followed by the coating of manganese dioxide （MnO2） on the surface. MWCNT can provide electronic conductive path to improve the conductivity of electrode material, while MnO2 has strong chemical adsorption to the polysulfide, thereby inhibiting the dissolution of polysulfide and enhancing the utilization of active materials. Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） characterization show that sulfur is uniformLy distributed across the carbon nanotubes and their surface is covered by a layer of manganese dioxide. The content of sulfur in MnO2@MWCNT-S composites is 58.4% by thermogravimetric analysis （TGA）. Electrochemical testing indicated that MnO2 coating has improved the initial capacity of MWCNT-S composite and effectively retarded the dissolution of polysulfides. The MnO2@MWCNT-S composite showed a high initial discharge capacity of 1148.98 mA.h.g-1 and maintained 560.04 mA.h.gq after 100 cycles at 0.1 C rate.

关 键 词：锂硫电池 多壁碳纳米管 MNO2 化学吸附作用 

分 类 号：TM912.9[电气工程—电力电子与电力传动]