二维二氧化钼/碳纳米管隔膜修饰层促进多硫化锂的催化转化  

Ultra-thin 2D MoO_(2) nanosheets coupled with CNTs as efficient separ-ator coating materials to promote the catalytic conversion of lithium polysulfides in advanced lithium-sulfur batteries

作　　者：孔振凯 陈阳[1] 华景朝 张永正 詹亮[1] 王艳莉[1] KONG Zhen-kai;CHEN Yang;HUA Jing-zhao;ZHANG Yong-zheng;ZHAN Liang;WANG Yan-li(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China;Jilin Jihua North Jinjiang Petrochemical Co.Ltd,Jilin 132022,China)

机构地区：[1]华东理工大学,化学工程联合国家重点实验室,上海200237 [2]吉林市吉化北方锦江石化有限公司,吉林吉林132022

出　　处：《新型炭材料》2021年第4期810-820,共11页New Carbon Materials

基　　金：国家自然科学基金(No.51472086,51002051,U1710252,50730003,50672025,20806024,22075081).

摘　　要：严重的穿梭效应和多硫化锂缓慢的反应动力学是阻碍锂硫电池商业化进程的两大主要障碍。本文通过化学气相沉积法合成超薄二维二氧化钼纳米片,并将其与碳纳米管复合作为锂硫电池隔膜修饰层以便解决以上两大问题。二维特性赋予了二氧化钼纳米片丰富的多硫化锂活性吸附位点;在H2/Ar混合气中的部分还原在二氧化钼表面引入了氧空穴,提升了其对多硫化锂转化反应的催化活性。碳纳米管导电网络的构建为持续稳定的多硫化锂反应提供了快速的电荷传递通道。对称电池测试显示二硫化钼/碳纳米管隔膜修饰层有效降低了硫化锂沉积的反应能垒;第一性原理计算进一步证实了其对多硫化锂的强锚定作用。所制锂硫电池展现出出色的循环稳定性,在1 C电流密度下循环800次,容量衰减率仅为每次0.053%。A severe shuttle effect and the slow kinetics of lithium polysulfide(LiPS)conversion are two major obstacles to the practical use of lithium sulfur batteries.Ultra-thin 2D MoO_(2) nanosheets(MoO_(2)NSs)have been synthesized by chemical vapor deposition and then mixed with carbon nanotubes(CNTs)for use as coating materials of the Celgard 2400 polypropylene separator to solve these problems.The 2D character of MoO_(2) NSs produced high surface/volume ratios and abundant active binding sites for anchoring LiPSs.In addition,the partial reduction of MoO_(2) NSs in a H2/Ar mixture introduced oxygen vacancies in their surface,which acted as catalytic sites for LiPS conversion,while the CNT network ensured rapid electron transfer for LiPS conversion reactions.Symmetric dummy cell tests showed that a 30wt%MoO_(2)/CNT coated separator reduced the energy barrier for Li2S nucleation,and first-principles calculations verified its strong binding energy to entrap LiPSs and increase Li2S precipitation.Because of these features,a cell with a 30wt%MoO_(2)/CNT coated separator had an improved specific capacity of 738 mAh·g^(-1) at 1 C with a slow decay rate of 0.053% for 800 cycles.

关 键 词：锂硫电池 二维材料 二氧化钼 碳纳米管 电催化 

分 类 号：TB33[一般工业技术—材料科学与工程]