Computational, electrochemical and ~7Li NMR studies of lithiated disordered carbons electrodes in lithium ion cells

摘要

Disordered carbons that deliver high reversibe capacity in electrochemical cells have been synthesized by using inorganic clays as templates to control the pore size and the surface area. The capacities obtained were much higher than those calculated if the resultant carbon had a graphitic-like structure. Computational chemistry was used to investigate the nature of lithium bonding in a carbon lattice unlike graphite. The lithium intercalated fullenere Li_n-C_(60) was used as a model for our (non-graphitic) disordered carbon lattice. A dilithium-C_(60) was used as a model for our (non-grapithic) disordered carbon lattice. A dilithium-C_(60) system with a charge and multiplicity of (0,1) and a trilithium-C_(60) system with a charge and multiplicity of (0,4) were investigated. The spatial distribution of lithium ions in an electrochemical cell containing this novel disordered carbon material was investigated in situ by Li-7 NMR using an electrochemical cell that was incroporated into a toroid cavity nuclear magnetic resonance (NMR) imager. The concentration of solvated Li~+ ions in the carbon anode appears to be larger than in the bulk electrolyte, is substantially lower near the copper/carbon interface, and does not change with cell charging.