负载ZnS的介孔碳复合硫正极材料的制备及性能研究

发布时间：2018-01-15 10:48

本文关键词：负载ZnS的介孔碳复合硫正极材料的制备及性能研究　出处：《福州大学》2014年硕士论文　论文类型：学位论文

【摘要】：本论文以获得高性能的锂硫电池正极材料为目的,对负载硫化锌(ZnS)的介孔碳复合硫正极材料的制备及性能进行了研究；与此同时,探讨不同的电解液添加剂对锂硫电池性能的影响。主要内容和结果如下：1.以蔗糖为碳源、SBA-15为模板制备介孔碳材料(MC),并以之为载体、硝酸锌为锌源、硫化钠为硫源,通过液相沉淀与回流一热处理相结合的方法制备负载ZnS的介孔碳复合材料(ZnS/MC);采用X射线粉末衍射、能谱(EDS)、扫描电子显微镜、透射电子显微镜以及氮气吸附脱附等手段对材料进行表征。结果表明,通过上述方法可以实现ZnS与介孔碳的复合,复合材料的比表面积、平均孔径、孔容均减小,其结构特征与介孔碳类似,仍保持着高度的多孔性,趋向于无定形物质；当ZnS含量低于17%时,不出现ZnS晶相,当ZnS含量超过17%时,复合材料中形成闪锌矿型ZnS晶相,ZnS主要以纳米微粒形式均匀分布于介孔碳表面和介孔碳孔道,有部分分布于球状碳间隙；当ZnS含量高于50%时,热处理时,ZnS纳米颗粒发生团聚。将ZnS/MC与S热复合制得负载ZnS的介孔碳复合硫正极材料ZnS/MC/S,采用循环伏安、交流阻抗、恒流充放电等测试手段考察其电化学性能,并探讨不同的ZnS负载量对锂硫电池性能的影响。结果表明,纳米化的ZnS可以催化多硫离子的电化学过程,提高硫电极的库仑效率及循环稳定性；ZnS含量为50%时,ZnS/MC/S电极的初始放电比容量达到1354.6mA h/g,初始可逆容量为1251.4 mA h/g,各循环阶段库仑效率接近100%,50次循环后容量仍有650 mA h/go2.探究LiNO3、SOC12等电解液添加剂对锂硫电池性能的影响。充放电测试显示,用LiNO3作添加剂,硫电极的初始放电比容量为1183.2mAh/g,50次循环后其比容量保持在696.4 mA h/g;用SOCl2添加剂,初始可逆容量达1252 mAh/g,且整个循环过程,库仑效率接近100%,60次循环之后,容量仍有641.8 mAh/g。在电解液中添加LiNO3N SOCl2,可有效抑制“飞梭效应”,提高硫电极性能。3.探究电解液中的多硫化物对锂硫电池性能的影响。结果显示,首次放电比容量达到1227 mAh/g,充放电效率一直维持在97%左右,循环50次循环后容量仍有664.5 mA h/g。用溶有多硫离子电解液的锂硫电池其放电容量与循环稳定性均得到提高。
[Abstract]:In this paper, in order to obtain high performance lithium sulfur battery cathode materials for the purpose of load of zinc sulfide (ZnS) preparation and properties of mesoporous carbon sulfur composite cathode materials were investigated; at the same time, to investigate the effects of electrolyte additives on the properties of lithium sulfur battery. The main contents and results are as follows: 1. with sucrose as carbon source, SBA-15 preparation of mesoporous carbon material as template (MC), and to the carrier, zinc nitrate as source of zinc, sodium sulfide as sulfur source, mesoporous carbon composite material prepared by loading ZnS liquid phase precipitation method combined with a reflux heat treatment system (ZnS/ MC) by X - ray powder; diffraction, energy spectrum (EDS), scanning electron microscope, the materials were characterized by transmission electron microscopy, N2 adsorption desorption method. The results show that the method can realize the composite ZnS and mesoporous carbon composite material, surface area, average pore size, pore volume decreased, The structure and characteristics of mesoporous carbon, remained highly porous, tends to amorphous material; when the content of ZnS is lower than 17%, no ZnS phase when the content of ZnS exceeds 17%, the zinc blende ZnS phase formed in the composite, ZnS is mainly in the form of nano particles evenly distributed on the dielectric mesoporous carbon surface and mesoporous carbon materials, partially distributed spherical carbon clearance; when the ZnS content is higher than 50%, heat treatment, ZnS nanoparticles aggregation. Mesoporous carbon sulfur composite cathode material ZnS/MC/S ZnS/MC and S ZnS composite prepared heat load, cyclic voltammetry, AC impedance, constant current charge discharge test means to investigate its electrochemical performance, and discusses the different effects of ZnS loading on the performance of lithium sulfur battery. The results show that the electrochemical process of nano ZnS can catalyze the polysulfide ions, improve coulombic efficiency and cycle stability of sulfur electrode; the content of ZnS is 50% When the initial discharge specific capacity of 1354.6mA electrode of ZnS/MC/S h/g, the initial reversible capacity of 1251.4 mA h/g, each cycle coulombic efficiency is close to 100%, after 50 cycles the capacity is still 650 mA h/go2. on LiNO3, SOC12 on the performance of electrolyte additive effects of lithium sulfur battery. The charge discharge tests showed that using LiNO3 as additive. The initial discharge of sulfur electrode capacity was 1183.2mAh/g, after 50 cycles the specific capacity remained at 696.4 mA h/g; with SOCl2 additive, the initial reversible capacity of 1252 mAh/g, and the whole cycle, the coulombic efficiency is close to 100%, after 60 cycles, the capacity is 641.8 mAh/g. with LiNO3N SOCl2 in the electrolyte, which can effectively inhibition of "shuttle effect", improve the performance of.3. on effect of sulfur electrode polysulfides in the electrolyte on the properties of lithium sulfur batteries. The results showed that the initial discharge capacity reached 1227 mAh/g, the charge discharge efficiency has dimension After holding 50 cycles for 97% cycles, the capacity is still 664.5 mA h/g., and the discharge capacity and cycling stability of lithium sulfur battery with multi sulfur ion electrolyte are improved.

【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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