Molecular orbital calculations on electronic and Li-adsorption properties of sulfur-, phosphorus- and silicon-substituted disordered carbons

Abstract

To clarify the effect of atom substitution on electronic and lithium (Li) adsorption properties of disordered carbons, we employed circum-coronene (C 54H 18) as a model cluster for disordered carbons and investigated the stable structures, electronic and Li-adsorption properties of its sulfur-, phosphorus- and silicon-substituted sheets, by using a semiempirical molecular orbital method. Among the three substituted sheets, the silicon-substituted Si 2C 52H 18 sheet was found to have desirable properties as an anode material of rechargeable Li-ion batteries: planar structure and large amount of Li adsorption. Although the Li-adsorption energy of Si 2C 52H 18 is smaller than that of B 2C 52H 18, the dependence of adsorption energy on the number of Li atoms indicates that Si 2C 52H 18 can adsorb more Li atoms than B 2C 52H 18. Therefore, silicon- as well as boron-substituted disordered carbons are expected to be promising materials for the anode in Li-ion batteries.