A theoretical investigation at density-functional level of Li ion conduction at the interfaces in ${\mathrm{Li}}_2\mathrm{O}:{\mathrm{B}}_2{\mathrm{O}}_3$ nanocomposites is presented. The structural disorder at the ${\mathrm{Li}}_2\mathrm{O}(111):{\mathrm{B}}_2{\mathrm{O}}_3(001)$ interface leads to reduced defect formation energies for Li vacancies and Frenkel defects compared to ${\mathrm{Li}}_2\mathrm{O}$ surfaces. The average activation energy for ${\mathrm{Li}}^{+}$ diffusion in the interface region is in the range of the values for ${\mathrm{Li}}_2\mathrm{O}$. It is therefore concluded that the enhanced Li conductivity of ${\mathrm{Li}}_2\mathrm{O}:{\mathrm{B}}_2{\mathrm{O}}_3$ nanocomposites is mainly due to the increased defect concentration.

• Received 2 November 2006

DOI:https://doi.org/10.1103/PhysRevLett.99.145502