Constructing hierarchical porous carbon via tin punching for efficient electrochemical energy storage

Abstract

To achieve large-scale preparation of high-performance carbon materials for electrochemical energy storage with a simple and cost-effective method remains a challenge. Here, we report a novel approach to synthesize hierarchical porous carbon with a low melting point metal tin (Sn) as pore forming agent. An aqueous processed tin chloride-polyethylene glycol (SnCl2-PEG) gel is used as precursor to form Sn/Carbon (Sn/C) composites with homogeneously distributed ultrafine Sn particles (<2 nm) by pyrolysis. After etching Sn nanoparticles, hierarchical porous carbon with high specific surface area (SSA: 846 m2 g−1) and abundant pore structure (coexistence of mesopore and micropore) was obtained. The SSA, pore size distribution and pore volume were successfully tuned by controlling the size of the Sn nanoparticle. The capacitive performance of the as-prepared hierarchical porous carbon was evaluated in 1 M H2SO4, which exhibits excellent specific capacitance of 240 F g−1. In order to further increase the electrochemical performance, N-doped porous carbon was fabricated by thermal nitridation in ammonia, which shows favorable features for electrochemical energy storage such as high specific surface area (1175 m2 g−1), uniform micropore volume (0.46 cm3 g−1) and rich nitrogen-doping (4.45 wt%). This N-doped sample exhibits outstanding specific capacitances of 360 F g−1 and excellent cycling stability in aqueous electrolytes. The above achievements indicate that combining low melting point metal as pore forming agent with a sol-gel protocol can be a unique and reliable method for preparation of high performance supercapacitor electrode materials.