Zhang Xinming, Liu Zichen, Liu Wen, Han Junwei, Lv Wei
Shenzhen Geim Graphene Center, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Advanced Chemical Engineering and Energy Materials Research Center, China University of Petroleum (East China), Qingdao 266580, China.
ACS Appl Mater Interfaces. 2023 Apr 19;15(15):19002-19010. doi: 10.1021/acsami.3c01512. Epub 2023 Apr 6.
High-performance metal-based catalysts are pursued to improve the sluggish reaction kinetics in lithium-sulfur batteries. However, it is challenging to achieve high catalytic activity and stability simultaneously due to the inevitable passivation of the highly active metal nanoparticles by lithium polysulfides (LiPSs). Herein, we show a design with well-balanced activity and stability to solve the above problem, that is, the cobalt (Co) nanoparticles (NPs) encapsulated with ultrathin carbon shells prepared by the one-step pyrolysis of ZIF-67. With an ultrathin carbon coating (∼1 nm), the direct exposure of Co NPs to LiPSs is avoided, but it allows the fast electron transfer from the highly active Co NPs to LiPSs for their conversion to the solid products, ensuring the efficient suppression of shuttling in long cycling. As a result, the sulfur cathode with such a catalyst exhibited good cycling stability (0.073% capacity fading over 500 cycles) and high sulfur utilization (638 mAh g after 180 cycles under a high sulfur mass loading of 7.37 mg cm and a low electrolyte/sulfur ratio of 5 μL mg). This work provides insights into the rational design of a protection layer on a metal-based catalyst to engineer both high catalytic activity and stability toward high-energy and long-life Li-S batteries.
人们一直在追求高性能的金属基催化剂，以改善锂硫电池中缓慢的反应动力学。然而，由于高活性金属纳米颗粒不可避免地会被多硫化锂（LiPSs）钝化，要同时实现高催化活性和稳定性具有挑战性。在此，我们展示了一种具有良好活性和稳定性平衡的设计，以解决上述问题，即通过对ZIF-67进行一步热解制备的包裹有超薄碳壳的钴（Co）纳米颗粒（NPs）。通过约1纳米的超薄碳涂层，避免了Co NPs直接暴露于LiPSs，但它允许电子从高活性的Co NPs快速转移到LiPSs，使其转化为固体产物，确保在长循环中有效抑制穿梭效应。结果，具有这种催化剂的硫正极表现出良好的循环稳定性（在500次循环中容量衰减0.073%）和高硫利用率（在硫质量负载为7.37毫克/平方厘米、电解质/硫比例低至5微升/毫克的情况下，180次循环后为638毫安/克）。这项工作为合理设计金属基催化剂上的保护层提供了见解，以实现对高能长寿命锂硫电池的高催化活性和稳定性。
