Radial channel boosting stress release in hollow carbon spheres for high-rate sodium ions storage

Abstract

Carbon spheres are appealing anode materials for advanced sodium ions batteries. However, several major hurdles to address are the stress-accumulation associated with the drastic volume change, the sluggish sodium ions diffusion kinetics, and poor electrochemically active sites inside. Herein, the von Mises stress distribution uncovers the critical role of the radial channel on the strain relaxation behavior based on the finite element method. Based on the finite element simulation, the radial porous hollow carbon spheres are proposed and synthesized by a universal strategy with a hard-template approach and dynamic graphitization. RPHCSs dominate opened micro-mesoporous features through the shell. With fast sodium ion diffusivity kinetics and much more accessible electrochemical active sites in shell, RPHCSs electrodes deliver a high specific capacity of 103.0 mAh g−1 even at 4000 mA g−1 with a high capacity contribution ratio > 0.1 V (81.1 %), suggesting its great superiority in the application of high-rate sodium ions storage. Such architecture provides a promising structural platform for the fabrication of high-performance carbon spheres material for other electrochemical energy storage systems.