摘要
在二次电池中,锂硫电池作为以硫为正极活性物质的电池形态,它具有原料环保且相对于其他传统材料更高比容量的特点。针对锂硫电池硫导电性差、膨胀率较大且充放电过程形成的多硫化锂易溶于电解液形成"穿梭效应"的不足,设计了一种以锂盐改性累托石为硫的宿主,碳硫复合的正极材料来改善锂硫电池的电化学性能。经测试,锂盐改性可以较大程度地疏通累托石的层间和孔道结构,增大比表面积和孔容,从而扩大硫在孔道中的负载空间,同时锂离子大量富集于材料中能有效提高充放电中离子和电子的传输。该改性正极复合材料在0.1 C倍率下首圈循环充放电比容量为877 mAh/g,60圈后比容量衰减为653 mAh/g,容量保有率为74.5%,说明材料中的成分能有效吸附多硫化物、抑制穿梭效应,使材料具有较好的循环稳定性。在电流密度0.1、0.2、0.5、1 C下平均比容量分别为850、750、600和500 mAh/g左右,表现出良好的倍率性能。其电荷转移阻抗为63Ω,有利于电子电荷的传导。
In the secondary battery,the lithium-sulfur battery is used as a battery form in which sulfur is used as a positive electrode active material,and it has the characteristics of environmentally friendly raw materials and higher specific capacity than other conventional materials.However,the sulfur conductivity is extremely poor,the expansion ratio is large,and the lithium sulfide formed by the charge and discharge process is easily dissolved in the electrolyte to form a″shuttle effect″.In view of the above shortcomings,a sulfur host by lithium salt modified rectorite and a carbon-sulfur composite cathode material were designed to improve the electrochemical performance of lithiumsulfur batteries.It has been tested that the lithium salt modification can dredge the interlayer and pore structure of the rectorite to a large extent,increase the specific surface area and pore volume,thereby expanding the loading space of sulfur in the pores,and at the same time enriching lithium ions in a large amount.The material can effectively improve the transport of ions and electrons in charge and discharge.The modified positive electrode composite has a charge-discharge specific capacity of 877 mAh/g in the first cycle at 0.1 C,and the specific capacity decay to 653 mAh/g after 60 cycles,and the capacity retention rate is 74.5%,indicating that the components in the material can effectively adsorb polysulfide.The components inhibit the shuttle effect and makes the material have better cycle stability.The average specific capacities at current densities of 0.1,0.2,0.5,1 C are 850,750,600,500 m Ah/g,respectively,and show good rate performance.Its charge transfer impedance is 63Ω,which is conducive to the conduction of electronic charges.
作者
罗贤盛
赵金卫
李京徽
余国贤
LUO Xiansheng;ZHAO Jinwei;LI Jinghui;YU Guoxian(School of Chemical and Environmental Engineering,Jianghan University,Wuhan 430056,Hubei,China)
出处
《江汉大学学报（自然科学版）》
2019年第6期499-506,共8页
Journal of Jianghan University：Natural Science Edition
基金
江汉大学研究生科研创新基金资助项目(Jhdxyjs17kz004)
关键词
锂硫电池
累托石
锂盐改性
电化学性能
lithium-sulfur battery
rectorite
lithium salt modification
electrochemical performance
