Zhang Qiang, Zhang Xu, Lei Da, Qiao Shaoming, Wang Qian, Shi Xiaoshan, Huang Chunhong, He Gaohong, Zhang Fengxiang
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116023, P. R. China.
School of Chemical Engineering, Dalian University of Technology, Panjin 124221, P. R. China.
ACS Appl Mater Interfaces. 2023 Mar 29;15(12):15377-15386. doi: 10.1021/acsami.2c21903. Epub 2023 Mar 17.
Transition-metal compounds can be used as electrocatalysts to expedite polysulfide conversion effectively in lithium-sulfur batteries. However, insufficient conductivity and tedious preparation process still limit their practical applications. In this work, NiCo alloy nanoparticles embedded in hollow carbon spheres (NiCo@HCS) are fabricated via a facile, template-free strategy from the NiCo-metal-organic framework (MOF) precursor and used as electrocatalysts for separator modification. NiCo@HCS can not only improve the adsorption capacity of polysulfides by d-band deviation to the Fermi level but also reduce the energy barrier in the process of catalytic polysulfide conversion. Due to favorable three-dimensional (3-D) morphology, improved adsorption, and promoted kinetics of NiCo@HCS, the battery containing the NiCo@HCS-modified separator gives a starting capacity of 1377 mAh g at 0.2C, which is retained by 72% over 500 charge/discharge operations at 1.0C current density. Moreover, the battery's start capacity reaches 1180 mAh g (5.9 mAh cm) with a high sulfur content of 5.0 mg cm at 0.2C.
过渡金属化合物可用作电催化剂，以有效加速锂硫电池中的多硫化物转化。然而，导电性不足和制备过程繁琐仍然限制了它们的实际应用。在这项工作中，通过一种简便的、无模板的策略，由镍钴金属有机框架（MOF）前驱体制备了嵌入中空碳球的镍钴合金纳米颗粒（NiCo@HCS），并将其用作隔膜改性的电催化剂。NiCo@HCS不仅可以通过d带向费米能级的偏移提高多硫化物的吸附能力，还可以降低催化多硫化物转化过程中的能垒。由于NiCo@HCS具有良好的三维（3-D）形态、改善的吸附性能和促进的动力学，含有NiCo@HCS改性隔膜的电池在0.2C下的起始容量为1377 mAh g，在1.0C电流密度下经过500次充放电循环后仍保留72%。此外，在0.2C下，当硫含量高达5.0 mg cm时，电池的起始容量达到1180 mAh g（5.9 mAh cm）。
