Wen Gongyu, Sui Yulei, Zhang Xiaoping, Li Jiangpeng, Zhang Ziwei, Zhong Shengkui, Tang Shibao, Wu Ling
School of Iron and Steel, Soochow University, Suzhou 215000, China.
School of Marine Science and Technology, Hainan Tropical Ocean University, Hainan 572000, China.
J Colloid Interface Sci. 2021 May;589:208-216. doi: 10.1016/j.jcis.2021.01.006. Epub 2021 Jan 7.
Lithium-sulfur batteries have attracted numerous attentions owing to their high theory discharge specific capacity and energy density. However, sulfur cathode usually suffers from poor cycle stability and slow reaction kinetics, caused by its poor conductivity, excessive volume changes during charge/discharge processes, complex sulfur species conversion reaction and the dissolution of polysulfide intermediates. Here, we present a free-standing framework of MnO nanoparticles combine with polypyrrole (PPy) nanotubes as host materials for lithium-sulfur batteries to overcome these issues. In this construction, PPy nanotubes serve as the excellent container of sulfur and physical barrier for the excessive volume expansion of sulfur during electrochemical reaction processes, and the nanotubes also provide an efficient conductive network for the rapid transmission of electrons and ions, while MnO nanoparticles facilitate trapping lithium polysulfides. The coordination of PPy nanotubes and MnO effectively alleviate the shuttle effect as well as enhance the utilization of sulfur. The obtained PPy@MnO-S sample shows high capacities of 1419.9 and 925.5 mAh g at 0.1 C and 1 C rate, respectively, and exhibits a low capacity fading rate of 0.062% per cycle for 800 cycles at 1 C rate. This work provides a new and effective way for the design of lithium-sulfur batteries with both high rate performance and long cycle stability.
锂硫电池因其高理论放电比容量和能量密度而备受关注。然而，硫正极通常存在循环稳定性差和反应动力学缓慢的问题，这是由其导电性差、充放电过程中体积变化过大、复杂的硫物种转化反应以及多硫化物中间体的溶解所致。在此，我们提出一种由MnO纳米颗粒与聚吡咯（PPy）纳米管结合而成的独立框架，作为锂硫电池的主体材料以克服这些问题。在这种结构中，PPy纳米管作为硫的优良容器以及电化学反应过程中硫过度体积膨胀的物理屏障，并且纳米管还为电子和离子的快速传输提供了高效的导电网络，而MnO纳米颗粒则有助于捕获多硫化锂。PPy纳米管与MnO的协同作用有效减轻了穿梭效应并提高了硫的利用率。所制备的PPy@MnO-S样品在0.1 C和1 C倍率下的比容量分别为1419.9和925.5 mAh g，并且在1 C倍率下循环800次时，容量衰减率低至每循环0.062%。这项工作为设计兼具高倍率性能和长循环稳定性的锂硫电池提供了一种新的有效方法。
