Layered carbon lattices and their influence on the nature of lithium bonding in lithium intercalated carbon anodes

Ab initio molecular orbital calculations have been used to investigate the nature of lithium bonding in stage 1 lithium intercalated carbon anodes. Th is has been approximated by using layered carbon lattices such as coronene, (C24H12), anthracene, and anthracene substituted with boron. With two coro nene carbon lattices forming a sandwich structure and intercalated with eit her two, three, four or six lithiums, it has been found th dr the predomina nt mode of bonding for the lithium is at the carbon edge sites as opposed t o bonding at interior carbon hexagon sites. With a single planar coronene m olecule approximating a graphene sheet, the bonding of four lithiums with t his molecule is near the interior carbon hexagon sites. For anthracene and boron substituted anthracene, Lithium bonding takes place within the carbon hexagon sites. The separation between lithiums in a sandwich type structur e with two anthracenes in the eclipsed conformation is 5.36 Angstrom. The e ffect of boron substitution is to increases lattice flexibility by allowing the lattice to twist and Lithium to bond at adjacent: hexagon sites. (C) 1 999 Elsevier Science S.A. All rights reserved.