Metal–Organic Framework-Derived Porous NiCo-Layered Double Hydroxide@MnO2 Hierarchical Nanostructures as Catalytic Cathodes for Long-Life Li–O2 Batteries

The commercial application of lithium–oxygen (Li–O 2 ) batteries has been seriously hindered by their large overpotential and inferior cycling performance caused by the insoluble and insulated traits of the discharge product, Li 2 O 2 . Herein, hierarchical hollow NiCo-LDH/MnO 2 hybrid nanostructures derived from metal–organic frameworks (MOFs) are successfully constructed as cathodes for Li–O 2 batteries to fundamentally improve the decomposition kinetics of Li 2 O 2 . The hollow NiCo-LDH/MnO 2 nanostructures assembled by hollow NiCo-LDH and MnO 2 nanosheets possess a highly special surface area, abundant open active sites, and a fast diffusion path for Li + and oxygen species. As expected, accelerated sluggish oxygen reduction reaction/oxygen evolution reaction kinetics and reduced charge/discharge overpotentials can be obtained. The toroidal Li 2 O 2 assembled by nanoflakes formed on the surface of the cathode can be conducive to form a low-impedance Li 2 O 2 /cathode contact interface to achieve the reversible formation and decomposition of Li 2 O 2 . The Li–O 2 battery based on the NiCo-LDH/MnO 2 cathode shows a high charge/discharge specific capacity of 13,380 mA h g –1 at 100 mA g –1 and a continuous cycling stability for 162 cycles at a fixed capacity of 500 mAh g –1 as well as a low overpotential of 0.63 V. Moreover, the application of MOF-derived porous hierarchical nanostructures expands the selection range of electrocatalysts and offers a new idea of structure design for Li–O 2 batteries.