Native defects in lithium amide (LiNH2), a promising candidate for hydrogen storage, are investigated by first-principles calculations based on density functional theory. We examine the structural properties and formation energies of H-, Li-, and N-related defects in all possible states. We find that the dominant H- and Li-related defects are in charged states, i.e., negatively charged H vacancy (VH-), positively charged H interstitial (Hi+), negatively charged Li vacancy (VLi -), and positively charged Li interstitial (ILi +). VLi- and ILi+ are present in the highest concentration. The positively charged NH2 vacancy has the lowest formation energy among N-related defects. Furthermore, migration processes of the dominant defects are investigated. V Li- diffuses most rapidly with the lowest migration energy of 0.20 eV. Both formation and migration energies of Li-related dominant defects are found to be lower than those of H-related dominant defects. With an activation energy of 0.72 eV, VLi- is the major diffusive species in LiNH2. Our results further indicate that the formation of Hi is the bottleneck for H transport.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jul 5 2011|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics