Jin Hong-Guang, Wang Mingyu, Wen Jian-Xin, Han Sheng-Hua, Hong Xu-Jia, Cai Yue-Peng, Li Guangli, Fan Jincheng, Chao Zi-Sheng
College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha, Hunan 410114, China.
School of Chemistry, Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, Guangdong Provincial Engineering Technology Research Center for Materials for Energy Conversion and Storage, South China Normal University, Guangzhou 510006, P. R. China.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):3899-3910. doi: 10.1021/acsami.0c18899. Epub 2021 Jan 13.
Mixed-valence metal-organic frameworks (MOFs) have exhibited unique potential in fields such as catalysis and gas separation. However, it is still an open challenge to prepare mixed-valence MOFs with isolated Ce(IV, III) arrays due to the easy formation of Ce under the synthetic conditions for MOFs. Meanwhile, the performance of Li-S batteries is greatly limited by the fatal shuttle effect and the slow transmission rate of Li caused by the inherent characteristics of sulfur species. Here, we report a mixed-valence cerium MOF, named CSUST-1 (CSUST stands for Changsha University of Science and Technology), with isolated Ce(IV, III) arrays and abundant oxygen vacancies (OVs), synthesized as guided by the facile and elaborate kinetic stability study of UiO-66(Ce), to work as an efficient separator coating for circumventing both issues at the same time. Benefiting from the synergistic function of the Ce(IV, III) arrays (redox couples), the abundant OVs, and the open Ce sites within CSUST-1, the CSUST-1/CNT composite, as a separator coating material in the Li-S battery, can remarkably accelerate the redox kinetics of the polysulfides and the Li transportation. Consequently, the Li-S cell with the CSUST-1/CNT-coated separator exhibited a high initial specific capacity of 1468 mA h/g at 0.1 C and maintained long-term stability for a capacity of 538 mA h/g after 1200 cycles at 2 C with a decay rate of only 0.037% per cycle. Even at a high sulfur loading of 8 mg/cm, the cell with the CSUST/CNT-coated separator still demonstrated excellent performance with an initial areal capacity of 8.7 mA h/cm at 0.1 C and retained the areal capacity of 6.1 mA h/cm after 60 cycles.
混合价态金属有机框架材料（MOFs）在催化和气体分离等领域展现出独特的潜力。然而，由于在MOFs合成条件下Ce易于形成，制备具有孤立Ce(IV, III)阵列的混合价态MOFs仍然是一个悬而未决的挑战。同时，锂硫电池的性能受到致命的穿梭效应以及硫物种固有特性导致的锂传输速率缓慢的极大限制。在此，我们报道了一种名为CSUST-1（CSUST代表长沙理工大学）的混合价态铈MOF，其具有孤立的Ce(IV, III)阵列和丰富的氧空位（OVs），在对UiO-66(Ce)进行简便且精细的动力学稳定性研究的指导下合成，用作高效的隔膜涂层以同时规避这两个问题。受益于CSUST-1中Ce(IV, III)阵列（氧化还原对）、丰富的OVs以及开放的Ce位点的协同作用，CSUST-1/碳纳米管（CNT）复合材料作为锂硫电池中的隔膜涂层材料，能够显著加速多硫化物的氧化还原动力学和锂的传输。因此，采用CSUST-1/CNT涂层隔膜的锂硫电池在0.1 C时表现出1468 mA h/g的高初始比容量，在2 C下经过1200次循环后容量保持在538 mA h/g，具有长期稳定性，每循环衰减率仅为0.037%。即使在8 mg/cm²的高硫负载下，采用CSUST/CNT涂层隔膜的电池在0.1 C时仍表现出优异的性能，初始面积容量为8.7 mA h/cm²，经过6
