全固态锂硫电池正极中离子输运与电子传递的平衡  

Balance between ion migration and electron transport in composite cathodes for all-solid-state lithium-sulfur batteries

作　　者：叶戈 袁洪 赵辰孜 朱高龙 徐磊 侯立鹏 程新兵[2] 何传新[3] 南皓雄 刘全兵 黄佳琦 张强[2] YE Ge;YUAN Hong;ZHAO Chenzi;ZHU Gaolong;XU Lei;HOU Lipeng;CHENG Xinbing;HE Chuanxin;NAN Haoxiong;LIU Quanbin;HUANG Jiaqi;ZHANG Qiang(Advanced Research Institute of Multidisciplinary Science,Beijing Institute of Technology,Beijing 100081,China;Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology,Department of Chemical Engineering,Tsinghua University,Beijing 100084,China;Shenzhen Key Laboratory of Functional Polymer,College of Chemistry and Chemical Engineering,Shenzhen University,Shenzhen 518000,Guangdong,China;School of Chemical Engineering and Light Industry,Guangdong University of Technology,Guangzhou 510006,Guangdong,China)

机构地区：[1]北京理工大学前沿交叉科学研究院,北京100081 [2]清华大学化学工程系绿色化学反应工程与技术北京市重点实验室,北京100084 [3]深圳大学化学与化工学院,功能高分子深圳市重点实验室,广东深圳518000 [4]广东工业大学轻工化工学院,广东广州510006

出　　处：《储能科学与技术》2020年第2期339-345,共7页Energy Storage Science and Technology

基　　金：国家重点研发计划(2016YFA0202500);国家自然科学基金(21825501,21808124,U1801257);北京市自然科学基金项目(L182021)。

摘　　要：全固态锂硫电池可抑制锂枝晶生长,且可避免多硫化物穿梭等问题,被认为是极具前景的下一代储能体系。固态正极中活性物质硫的绝缘性,使得电化学氧化还原需要离子传输和电子传递网络的双连通。而如何平衡固态正极中离子输运与电子传递路径是实现电池稳定运行的关键。面向未来高比能储能体系,本文在40%(质量分数,下同)的高硫含量复合正极中,通过调控复合正极中电子导体碳纳米管(CNT)与离子导体Li10GeP2S12(LGPS)相对含量,借助扫描电子显微镜(SEM)、X射线衍射(XRD)与拉曼测试以及电化学测试与表征等,考察不同CNT与LGPS比例下硫正极的电子导率与离子导率,并通过对比硫正极的首圈放电容量以及在第二圈的容量保持率,从而探索正极设计的离子通路与电子通路的最优平衡条件。结果表明,硫正极中LGPS电解质含量低时,锂离子传输受阻;当LGPS电解质含量高时,电子传递阻力大且反应活性界面有限。因此,综合对比放电容量与容量保持率,可以得出40%高硫含量正极中,离子输运与电子传递的最优平衡条件是CNT和LGPS的含量分别为15%和45%,此时全固态锂硫电池首圈放电比容量621 mA·h/g,容量衰减率为3%。All-solid-state lithium-sulfur batteries(ASSLSBs) are strong candidates for next-generation energy-storage systems owing to their high theoretical energy density and the ability to eliminate the shuttle effect. The insulation of sulfur in solid-state cathodes requires additional ionic and electronic conductors, where the balance between ion and electron transport is crucial for a stable electrochemical reaction. In addition, for high-energy-density batteries, it is important to develop composite cathodes with high sulfur content and less amount of inactive substances. Herein, we investigate the balance between ion migration and electron transport by adjusting the content of sulfide electrolyte Li10GeP2S12(LGPS) and carbon nanotubes(CNTs) under high sulfur content(40% of weight fraction). Sulfur cathodes were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), and Raman spectroscopy. The ionic and electronic conductivities of composite cathodes were measured separately. Electrochemical tests indicate that ion transportation is hindered when LGPS content reduces, while the electronic conductivity is limited by the considerable excess of LGPS electrolytes.By comparing the specific capacity in the first cycle and capacity retention in the following cycle, we conclude that the optimal solution should contain 15% CNT and 45%(weight fraction) LGPS. In this case, the discharge specific capacity of ASSLSBs is 621 m A·h·g-1 and the rate of capacity decay is 3%.

关 键 词：全固态锂硫电池 硫化物电解质 复合正极 离子电子输运 高硫含量 

分 类 号：TM911[电气工程—电力电子与电力传动]