Dongdong Li,Qian Zhang,Zhichuan Shen,Kumar Siddharth,Lijuan Chen,Minhua Shao,Zhicong Shi
Rechargeable lithium oxygen batteries (LOBs) are one of the most promising energy storage systems by virtue of their high energy density and environmental amiability. However, the development of LOBs is still hindered by some critical issues. Herein, 3D hexapod-shaped Co-ZIFs-thiourea/dimethyl sulfoxide (H-Co-ZIFs-S) derived Co nanoparticles embedded into nitrogen and sulfur co-doped carbon (H-Co-NSC) are developed, and then low content of ruthenium nanoparticles are decorated on the surface to obtain Ru/H-Co-NSC as efficient catalyst for LOBs. The Ru/H-Co-NSC catalysts exhibits unique structure and catalytic properties , such as accommodating the insoluble discharge product Li 2 O 2 , promoting the transportation of ions/O 2, enhancing the electronic conduction, demonstrating excellent OER/ORR kinetics as well. In addition, the Ru-decorated nanoparticles could effectively suppress some side-reactions caused by the exposed carbon of H-Co-NSC in LOBs. First-principles Density functional theory (DFT) calculations reveal the cooperative effect of multiple active sites in Ru/H-Co-NSC can effectively promote the ORR/OER kinetics in LOBs. Therefore, the LOBs with Ru/H-Co-NSC cathode provide a positive catalytic capacity with low overpotential, large specific capacities, long cycle life and superior reversibility . Our work may pave the way to design more advanced catalysts for metal-air batteries with superior electrochemical performance.
A novel free-standing and binder-free air electrode with excellent electrochemical performance was designed for highly reversible Li–O2 batteries. The 3D hierarchically N, S co-doped macro–mesoporous carbon (NSMmC) was deposited on carbon paper (CP) via a template method, and then uniformly decorated with PdNi nanoparticles. The macropores of the porous carbon can provide enough space to accommodate discharge products, while the interconnected pores and channels efficiently facilitate oxygen and electrolyte diffusion. The introduction of PdNi nanoparticles greatly reduce the charge transfer resistance, resulting in the improvement of electron mobility of the whole cathode. Compared with Pd–NSMmC/CP and NSMmC/CP cathodes, the PdNi–NSMmC/CP cathode shows considerable enhancement of Li–O2 battery performance. The ultrafine and evenly distributed PdNi nanoparticles can not only provide enough catalytic sites, but can also tailor the discharge products into a cage-like morphology, which provides enough channels for electron and lithium ion transport. Moreover, the smaller size of the cage-like Li2O2 makes it decompose more easily, resulting in lower charge overpotential. This study provides a promising strategy to design 3D structured air cathodes for Li–O2 batteries with high electrocatalytic performance.
The metallic phase MoS 2 (1T-MoS 2 ) supported metal-nanocatalyst is an appealing material system for accelerating the redox kinetics of non-aqueous Li | |O 2 batteries. However, the drawbacks associated with the surface orbital steric effect and the internal electron coupling results in a detrimental effect for the stability of 1T-MoS 2 , especially for the interface charge transfer. This makes it difficult to incorporate guest metal nanoparticles without compromising the 1 T phase support. To circumvent these issues, here we propose a p-block element (In-O) doping strategy to stabilize the 1 T phase MoS 2 by moderating the surface orbital steric effect and strengthening the internal chemical bonding, and thus for the epitaxial Ru nanocatalyst graft on the stabilized 1T-MoS 2 for Li | |O 2 batteries. The experimental and theoretical analyzes indicate that the In-O-MoS 2 @Ru enhances the O 2 dissociation and facilitates the adsorption of LiO 2 intermediates. This effect promotes the growth of weakly crystalline Li 2 O 2 films during oxygen reduction reaction, which can be more easily decomposed during the oxygen evolution reaction, thereby enhancing the bifunctional-catalytic kinetics. When employed at the positive electrode for non-aqueous Li | |O 2 batteries, In-O-MoS 2 @Ru shows an overpotential of 0.37 V and a cycling life of 284 cycles at 200 mA g −1 with a final discharge specific capacity of 1000 mAh g −1 at 25 °C.
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