Sea urchin-like Co3O4@Pd Nanoneedles with 3D open-structured matrix as efficient catalytic cathode for Li-O2 batteries

• Published in: Solid state ionics 2019-12, Vol.343, p.115075, Article 115075
• Main Authors: Li, Jiajie, Wang, Zicheng, Xu, Huaizhe, Li, Honglei, Yang, Puheng, Jian, Zhixu, Xing, Yalan, Zhang, Shichao, Ren, Yanbiao
• Format: Article
• Language: English
• Subjects: 3D open-structured catalyst; Batteries; Catalysts; Catalytic activity; Cathodes; Co3+ ions; Cobalt oxides; Electrocatalysis; Electrodes; Lithium; Lithium‑oxygen batteries; Long cycle life; Metal air batteries; Metal foams; Morphology; Palladium; Sea urchin-like cobalt oxide; Structured matrices; Transition metals
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2019.115075

In this study, both morphology-related factors and catalytic activity factors were taken into account simultaneously and sea urchin-like Co3O4 nanoneedles grown on nickel foam were synthesized via a facile hydrothermal strategy (grass-like Co3O4 were also prepared for comparison). Most noteworthy is that 3D open-structured sea urchin-like Co3O4 exposing more Co3+ sites with large specific surface area and abundant mesoporous structure exhibited superior electrocatalytic performance as compared to 1D structured grass-like Co3O4 and former reported 3D structured electrodes (i.e., urchin shaped, flower shaped). Pd decorated sea urchin-like Co3O4 was also prepared through a simple impregnationmethod. When served as binder/carbon-free catalytic cathode for Li-O2 batteries, the problems about limited capacity, large overpotential and poor cycle life were effectively improved. The catalytic electrode displayed a low overpotential of 1.12 V, high specific capacity (8819.2 mA h g−1) at a current density of 200 mA g−1 and long cycle life with the capacity limited at 500, 1500, 2500, even 3500 mA h g−1, overmatching most of the transition-metal-oxides based catalytic electrodes, which are intrinsically dependent on the characteristic design in both morphology and catalytic active sites of the electrodes. Long cycle life of Li-O2 battery is attributed to the tailored design in both 3D open-structured morphology and catalytic sites of urchin-like Co3O4 electrode. [Display omitted] •Morphology and catalytic activity factors are all taken into account to design efficient catalytic cathode.•Large surface area of 3D open-structured matrix can provide abundant space for Li2O2 to accommodate.•Co3+ plays a crucial role in catalytic reaction.•Pd can effectively ensure the uniform deposition of a fluffy Li2O2 layer.