Pt Nanoparticles-Macroporous Carbon Nanofiber Free-Standing Cathode for High-Performance Li-O2 Batteries

Controlling the pore structure of cathodes has a decisive effect on the performance of lithium (Li)-O2 batteries. In this work, macroporous carbon nanofiber (MCNF) decorated with Pt nanoparticles (PtNPs) (PtNP-MCNF) are successfully fabricated. Their electrochemical performance as cathodes for a Li-O2 battery is evaluated. The MCNF mats are fabricated through an electrospinning and templating method using cross-linked polystyrene particles. PtNPs are grown on the surface of the MCNF through a solvothermal reaction. As-prepared PtNP-MCNF has interconnected macropores along the MCNF interior and abundant surface openings. These macropores are also connected to larger pores between individual MCNFs through the orifices on the MCNF surface, rendering a hierarchical porous structure. Owing to the highly porous structure and catalytic activity of PtNPs, Li-O2 cells using PtNP-MCNF cathodes exhibit considerably improved performance. In particular, with regard to cycle stability, the Li-O2 cell using PtNP-MCNF attains over 470 cycles in total while discharging at a capacity of 1000 mAh gc −1 with a current density of 500 mA gc −1. Such a high performance of the Li-O2 cell can be attributed to a facilitated Li+ and O2 transportation through the highly porous structure, and highly reversible Li-O2 operation over its life-cycle by means of catalytic activity of PtNPs.