Hierarchical porous carbon/selenium composite derived from hydrothermal treated peanut shell as high-performance lithium ion battery cathode

Peanut shell-derived porous carbon has been prepared by the KOH-assisted hydrothermal treatment and subsequent carbonization route. The influences of KOH concentrations on structure of resulting carbon are clearly studied. At a KOH concentration of 5 M, the obtained porous carbon, possessing inner micropores and surface macropores, has a specific surface area of 827.7 m(2)/g and moderate porous size. The amorphous Se is uniformly encapsulated into its microporous structure to form hierarchical porous carbon/selenium composite. As the cathode material of Li ion battery, this composite delivers an initial discharge capacity of 590.6 mA h/g with Coulombic efficiency of 71.6% at 0.2 C, and a high capacity retention ratio of 83.3% can be reached after 500 cycles at 2 C. Even at a high rate of 4 C, this composite still presents a discharge capacity of 405.8 mA h/g. By comparison, these improved electrochemical performances may be attributed to the hierarchical porous feature, moderate porous size and effective encapsulation of selenium.