Pu Jun, Gong Wenbin, Shen Zhaoxi, Wang Litong, Yao Yagang, Hong Guo
Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade Taipa, Macau SAR, 999078, China.
School of Physics and Energy, Xuzhou University of Technology, Xuzhou, 221018, China.
Adv Sci (Weinh). 2022 Feb;9(4):e2104375. doi: 10.1002/advs.202104375. Epub 2021 Dec 11.
The "shuttle effect" of soluble polysulfides and slow reaction kinetics hinder the practical application of Li-S batteries. Transition metal oxides are promising mediators to alleviate these problems, but the poor electrical conductivity limits their further development. Herein, the homogeneous CoNiO /Co N nanowires have been fabricated and employed as additive of graphene based sulfur cathode. Through optimizing the nitriding degree, the continuous heterostructure interface can be obtained, accompanied by effective adjustment of energy band structure. By combining the strong adsorptive and catalytic properties of CoNiO and electrical conductivity of Co N, the in situ formed CoNiO /Co N heterostructure reveals a synergistic enhancement effect. Theoretical calculation and experimental design show that it can not only significantly inhibit "shuttle effect" through chemisorption and catalytic conversion of polysulfides, but also improve the transport rate of ions and electrons. Thus, the graphene composite sulfur cathode supported by these CoNiO /Co N nanowires exhibits improved sulfur species reaction kinetics. The corresponding cell provides a high rate capacity of 688 mAh g at 4 C with an ultralow decaying rate of ≈0.07% per cycle over 600 cycles. The design of heterostructure nanowires and graphene composite structure provides an advanced strategy for the rapid capture-diffusion-conversion process of polysulfides.
可溶性多硫化物的“穿梭效应”和缓慢的反应动力学阻碍了锂硫电池的实际应用。过渡金属氧化物是缓解这些问题的有前景的介质，但较差的导电性限制了它们的进一步发展。在此，制备了均匀的CoNiO/Co N纳米线并将其用作基于石墨烯的硫正极的添加剂。通过优化氮化程度，可以获得连续的异质结构界面，并伴随着能带结构的有效调整。通过结合CoNiO的强吸附和催化性能以及Co N的导电性，原位形成的CoNiO/Co N异质结构显示出协同增强效应。理论计算和实验设计表明，它不仅可以通过多硫化物的化学吸附和催化转化显著抑制“穿梭效应”，还可以提高离子和电子的传输速率。因此，由这些CoNiO/Co N纳米线支撑的石墨烯复合硫正极表现出改善的硫物种反应动力学。相应的电池在4 C下提供688 mAh g的高倍率容量，在600次循环中具有≈0.07%/循环的超低衰减率。异质结构纳米线和石墨烯复合结构的设计为多硫化物的快速捕获-扩散-转化过程提供了一种先进策略。
