微波诱导等离子体技术制备rGO@S复合正极及其在高倍率锂硫电池中的应用

Preparation of rGO@S composite cathode material by microwave induced plasma method and its application in high-rate lithium-sulfur batteries

锂硫电池具有高能量密度、低成本和环境友好等优势,有望满足市场日益增长的需求。然而,其正极材料中的活性物质硫存在溶解穿梭等问题,限制了锂硫电池的大规模应用。本文利用氧化石墨(GO)作为碳源、升华硫作为硫源,通过微波诱导等离子体技术(MIP)快速高效(30-40 s)地制备得到了还原氧化石墨烯负载硫纳米颗粒锂硫电池复合正极材料(rGO@S),其中,rGO褶皱卷曲、相互连接的层片状结构,有利于电解液中的锂离子向电极材料中扩散和迁移,同时有利于提高电极材料的导电性,且rGO上的含氧官能团也能够起到对硫纳米颗粒的固定作用,有利于电极材料循环稳定性的提升。得益于其独特的形貌结构,rGO@S在电池测试中表现出优异的倍率性能和良好的循环稳定性。在0.1 A·g^(-1)的电流密度下,rGO@S的可逆比容量为1036 mAh·g^(-1),当电流密度增大到8 A·g^(-1)其可逆比容量仍高达832 mAh·g^(-1),且经过8 A·g^(-1)的超大电流密度充放循环,当电流密度回到0.1 A·g^(-1)时,其可逆比容量迅速恢复至1040 mAh·g^(-1),几乎没有容量衰减。

Lithium-sulfur batteries have the advantages of high energy density,low cost and environmental friendliness,which are ex-pected to meet the growing market demand.However,the active material sulfur in its cathode material has problems such as dissolu-tion shuttle,which limits the large-scale application of lithium-sulfur batteries.In this paper,graphite oxide(GO)was used as a car-bon source and sublimed sulfur was used as a sulfur source.The reduced graphene oxide-supported sulfur nanoparticle composite cathode material(rGO@S)was rapidly and efficiently prepared by microwave-induced plasma method(MIP)(30-40 s).Among them,rGO has an open porous and interconnected lamellar structure,which is conducive to the diffusion and migration of lithium i-ons from the electrolyte into the electrode material,and is conducive to improving the conductivity of the electrode material.The oxy-gen-containing functional groups on rGO can also play a role in fixing sulfur nanoparticles,which is conducive to the improvement of the cycle stability of the electrode material.Thanks to its unique morphology,rGO@S exhibits excellent rate performance and good cycle stability in battery tests.At a current density of 0.1 A·g^(-1),the reversible specific capacity of rGO@S is 1036 mAh·g^(-1).When the current density increases to 8 A·g^(-1),the reversible specific capacity is still as high as 832 mAh·g^(-1).And after 8 A·g^(-1)ultra-high current density charge-discharge cycle,when the current density returns to 0.1 A·g^(-1),its reversible specific ca-pacity quickly recovers to 1040 mAh·g^(-1),with negligible capacity decay.