Sculpturing solid polymer spheres into internal gridded hollow carbon spheres under controlled pyrolysis micro-environment

Porous carbon spheres with an internal gridded hollow structure and microporous shell have always been attractive as carbon hosts for electrochemical energy storage. Such carbon hosts can limit active species loss and enhance electronic conductivity throughout the entire framework. Herein, a synthesis approach of internal gridded hollow carbon spheres is developed from solid polymer spheres rather than originally gridded polymer spheres under a controlled pyrolysis micro-environment. The crucial point of this approach is the fabrication of a silica fence around solid polymer spheres, under which the free escaping of the pyrolysis gas will be partly impeded, thus offering a reconstitution opportunity for an internal structure of solid polymer spheres. As a result, the interior of carbon spheres is sculptured into a gridded hollow structure with microporous skin. Furthermore, the size and density of carbon-bridge grids can be modulated by altering the crosslinking degree of polymer spheres and varying pyrolysis conditions. Such gridded hollow carbon spheres show good performance as sulfur hosts for Li-S battery.