Fe2O3-石墨烯-碳纳米管复合材料制备条件对载硫性能的影响

Effect of preparation conditions of Fe2O3-graphene-carbon nanotube composites on sulfur loading properties

  • 摘要: 锂硫电池是传统锂离子电池最有前途的替代品之一,多硫化物的溶解和导电性差是制约锂硫电池应用的两个重要因素。通过水热法合成了Fe2O3-还原氧化石墨烯(RGO)-碳纳米管(CNT)复合载硫材料,并通过调节氨水浓度,实现了复合材料中Fe2O3的颗粒尺寸的有效调控,发现小尺寸的Fe2O3颗粒具有更好的吸附和催化作用。合成的Fe2O3-RGO-CNT-S正极材料在1 C倍率下首次放电容量为1286 mA·h/g,循环500圈后剩余718 mA·h/g,每圈的容量衰减率为0.08%。在0.2、0.5、1、2和4 C倍率下的平均比容量为983、825、769、673和604 mA·h/g,具有良好的倍率性能。在5 C倍率下循环500次仍剩余527 mA·h/g,具有良好的大电流循环性能。Fe2O3-RGO-CNT-S正极材料特别适用于高性能锂硫电池,具有优异的电化学性能主要是由于RGO和CNT三维导电网络提供了强电子传输路径、丰富的孔隙结构、硫与RGO和CNT构成的三维导电网络充分接触。

     

    Abstract: Lithium sulfur battery is one of the most promising alternatives to traditional lithium-ion battery. The dissolution and poor conductivity of polysulfides are two important factors restricting the application of lithium sulfur battery. In this paper, Fe2O3-reduced graphene oxide (RGO)-carbon nanotube (CNT) composite sulfur carrying materials are synthesized by hydrothermal method. By adjusting the ammonia concentration, the particle size of Fe2O3 in the composites is successfully adjusted. It is found that Fe2O3 with small particles had better adsorption and catalysis. Cathode material synthesized from it at 1 C, the first discharge capacity is 1286 mA·h/g, 718 mA·h/g remains after 500 cycles, and the capacity attenuation rate of each cycle is 0.08%. The average specific capacities at 0.2, 0.5, 1, 2 and 4 C are 983, 825, 769, 673 and 604 mA·h/g, which has good rate performance and good cycle performance at high current. 527 mA·h/g remains after 500 cycles at 5 C. Fe2O3-RGO-CNT-S cathode material is especially suitable for high-performance lithium sulfur batteries. It has excellent electrochemical performance, mainly because the three-dimensional conductive network of RGO and CNT provides strong electron transmission path, rich pore structure, and sulfur is in full contact with the three-dimensional conductive network composed of RGO and CNT.

     

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