Orderly meso-perforated spherical and apple-shaped 3D carbon microstructures for high-energy supercapacitors and high-capacity Li-ion battery anodes

The Stöber synthesis, which is composed of two steps of the formation of RF resin spheres in presence of an NH₃ catalyst and the carbonization of RF resin spheres under an inert atmosphere, is a well-known approach to the preparation of carbon spheres (CSs). We herein modified the first step of the Stöber procedure to introduce morphological and physicochemical changes to CSs. Two different fully perforated 3D carbon-based micromaterials were prepared, namely spherical meso-perforated carbon (SSMPC) and apple-shaped meso-perforated carbon (ASMPC). In the preparation of these materials, we adopted colloidal silica-mediated spray drying method followed by carbonization and silica removal. High specific surface areas and pore volumes were achieved for both ASMPC (1141 m² g^-1 and 3.2 cm³ g^-1) and SSMPC (1050 m² g^-1 and 2.1 cm³ g^-1). We then evaluated the charge storage properties in organic media from supercapacitor (SC) as well as Li-ion battery (LIB) perspectives. An ASMPC-based symmetric SC was capable of delivering a specific capacitance and energy density of 260 F g^-1 and 75.56 W h kg^-1, respectively, in addition to an excellent cyclability of 30 000 cycles. In the LIB, ASMPC exhibited a maximum capacity of 1698 mA h g^-1 after 175 cycles at 200 mA g^-1. We systematically elaborated that inaccessible interior sites of the 3D CSs could become accessible through the introduction of meso-perforations on the periphery and in the interior. We expected that the 3D shape and meso-perforations were responsible for the exceptional performance of CSs in SCs and LIBs.