Porous carbon nanoplate/Se composite derived from potassium citrate as high-performance Li-Se battery cathode: A study on structure-function relation

Abstract

Porous carbon box or nanoplate has been prepared by synchronous carbonization/activation of potassium citrate, and the corresponding porous carbon nanoplate/Se composite can be obtained using a melting-diffusion method. The influence of structure parameters including specific surface area and porous structure of porous carbon and resultant carbon/Se composite on electrochemical properties are studied. It is found a moderate micropore size of carbon substrate and low specific surface area of carbon/Se composite are benefit to electrochemical performances. At an optimal temperature of 700 °C, the porous carbon composed of micro- and small meso-porous (2–4 nm) structure has a BET specific surface area of 695.4 m2 g−1, and the amorphous Se is uniformly encapsulated into its porous structure. As the cathode material of Li ion battery, the porous carbon nanoplate/Se composite delivers an initial discharge capacity of 589.2 mAh g−1 with Coulombic efficiency of 72.6% at 0.2C, and capacity retention of 78.3% can be obtained after 500 cycles at 2C. Even at a high rate of 4C, a discharge capacity of 415.2 mAh g−1 can be reached.