Structure of heat-treated mesoporous carbon and its electrochemical lithium intercalation behavior

Mesoporous carbon (MPC) was synthesized via the thermal decomposition of magnesium citrate in a flow of Ar gas, followed by dissolution of MgO nanoparticles in the carbonaceous pyrolysis product. The MPC was then heated at 1800, 2000, 2200, 2400, 2500, 2700 and 3000 degrees C for 30 mm. The MPC samples heated at 1800 and 2000 degrees C having a mesopore structure with graphitized carbon walls exhibited an enhanced rate capability as a composite anode for lithium ion batteries. Heat treatment of the MPC from 2200 to 2700 degrees C led to a partial collapse of micropores and mesopores, which decreased the charge/discharge capacity. The MPC samples heated at 2700 and 3000 degrees C having thick graphitized carbon layers and a mesopore structure with graphitized carbon walls showed charge/discharge curves with three lithium intercalation potential plateaus at approximately 0.2, 1.0, and 1.5 V vs. Li/Li+. The MPC sample heated at 3000 degrees C was the best anode material for lithium ion batteries among the MPC samples evaluated in this study because of its low irreversible capacity, high columbic efficiency, and high rate capability. (C) 2014 Elsevier B.V. All rights reserved.