Large Scale Synthesis High Performance N‒Doped Carbon Spherical Shell as Advanced Cathode Materials for Li‒X (X=O2, S, Se) Batteries

Abstract

Porous carbon spherical shell with ordered pore structure have been reported. However, their prepared method is complex and high‒energy consuming resulting in very small amount of samples. In this study, we report a gram‒scale preparation of hierarchical meso‒/macro‒porous carbon spherical shell. Raman and BET characterization reveal that the spherical shell have high degree of graphitization and high surface are of 893.3 m2 g‒1. In addition, a certain amount of nitrogen doping are benefit to the good catalytic activity of the material. When used as the cathode materials for Li‒O2 batteries, the optimized three‒dimensional channels within the material not only can facilitate the transportation of oxygen, lithium ion and electrons, but also host accommodate the discharge product both inside and outside the shell. This results in ultrahigh discharge capacity of 11038 mAh g‒1 or 7.85 mAh cm‒2. Moreover, when assembling Li‒S/Li‒Se battery with S and Se infiltrated into the nanocomposite, favorable electrochemical performance is observed in terms of specific capacity (Li‒S:1336.8mAh g‒1; Li‒Se: 829.3 mAh g‒1), cycling stability (after 270 cycle capacity retention of 661.5 mAh g‒1 for Li-S; after 1000 cycle capacity retention of 150.1 mAh g‒1 for Li‒Se), and high rate capability.

Keywords: Spray drying, Hierarchical porous hollow carbon spheres, Li‒O2 battery, Li‒S battery, Li‒Se battery