Controlling the Inner Structure of Carbon Spheres via “Protective-Dissolution” Strategy for Supercapacitor

Hollow, yolk–shell, and core–shell carbon spheres have attracted substantial attention, because of their unique structure and potential application in energy storage/conversion. Unfortunately, the structural adjustment of the carbon sphere mostly depends on the template method with a tedious process, and most of the methods are not conductive to large-scale production. Furthermore, one particular structure requires one specific strategy. Here, the carbon spheres with hollow, yolk–shell, and core–shell structure are prepared via a facile and feasible “protective-dissolution” strategy. A suitable amount of acetone is used to dissolve the core of resorcinol-formaldehyde (RF) resin as an effective solvent, and also to regulate the structure as a critical controlling factor. The dissolved resin oligomer assembled outside of the undissolved RF resin sphere under the action of cetyltrimethylammonium (CTAB), forming a strong polymer shell which prevents the RF resin sphere from further dissolution in acetone. The obtained carbon sphere with the especially hollow structure shows a large cavity, high specific surface area, and excellent electrochemical performance with high capacitance of 272 F g–1 at 1 A g–1, and the capacitance retention is 95.2% after 10 000 charge–discharge cycles at 5 A g–1. These outstanding properties and remarkable performance make them potential as supercapacitor electrode materials