锂硫电池具有高理论能量密度和低成本的优势,在储能领域应用前景广阔。然而,正极材料单质硫的导电性差和熔点低的问题很大程度上阻碍了其发展。将纳米硫与导电性良好的碳纳米纤维混合,然后将硫碳混合材料(S/C)分别置于气体(空气)和液体(环己烷)氛围中并施加压力,得到2种块状材料(记作空气-S/C和环己烷-S/C),于220℃高温条件下加热8h得到硫碳复合材料(记作空气-S@C和环己烷-S@C)。通过热重分析仪、场发射扫描电子显微镜、电化学工作站等对材料的热稳定性能、微观形貌和电化学性能进行分析和测试。结果表明,压制过程中的氛围条件直接影响施压效果,环己烷的液态氛围施压效果优于空气氛围施压效果。环己烷-S/C的强度更高且在高温烧结过程中的硫损耗更低,有利于提高活性物质硫的利用率。采用环己烷-S@C作为正极材料的锂硫电池在0.1C倍率下初始比容量高达1358mAh/g,在0.2C倍率下循环100次后比容量仍保持815mAh/g。
Lithium-sulfur (Li-S) batteries offer high theoretical energy density and low cost,making them promising candidates for energy storage applications.However,the poor conductivity and low melting point of sulfur as cathode material hinder their development to a great extent.Nano sulfur was mixed with carbon nanofibers with good conductivity,and then the sulfur-carbon hybrid materials (S/C) were placed in two atmospheres of gas (air) and liquid (cyclohexane) and applied with pressure to obtain two types of bulk materials (recorded as air-S/C and cyclohexane-S/C).Finally,the sulfur-carbon composites were obtained by heating at 220℃ for 8h (recorded as air-S@C and cyclohexane-S@C).The thermal stability,micro morphology and electrochemical properties of the materials were analyzed and tested by thermogravimetric analyzer,field emission scanning electron microscope and electrochemical workstation.The results showed that the pressurization effect was directly affected by the atmosphere conditions during the pressing process,and the pressurization effect of liquid atmosphere of cyclohexane was better than that of air atmosphere.cyclohexane-S/C had higher strength and lower sulfur loss during high-temperature sintering,which was conducive to improving the utilization rate of active sulfur material.The Li-S batteries using cyclohexane-S@C as the cathode material not only provided an initial capacity of up to 1358mAh/g at 0.1C rate,but also maintained a specific capacity of 815mAh/g after 100 cycles at 0.2C rate.
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基金资助
国家自然科学基金(51273027);2022年江苏省研究生科研与实践创新计划(KYCX22＿3095)
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