Electrode Materials Away from Equilibrium for Lithium-Ion Intercalation

Lithium-ion batteries store electrical energy in the form of chemical potential, the same as that in primary batteries; however, the charge-discharge process in lithium-ion batteries is more complex as it involves not only Faradaic reactions at the interface between electrodes and electrolyte, but also is accompanied with mass and charge transport and volume change of the electrodes that commonly possess low electrical conductivity. Electrodes away from thermodynamic equilibrium include nanostructures with high surface energy, poor-crystalline materials, and materials with significant surface or bulk defects. Such materials are in higher energy state and, thus, easier for phase transfer and nucleation; such materials also have less closely packed structure, permitting faster mass transport and accommodating more lithium-ions as well as tolerating more volume change. This presentation will take vanadium pentoxide and lithium titanate as two model materials to illustrate the influences of doping, surface defects and carbon coating, and nanostructures on the lithium-ion intercalation properties.