Electrons and phonons of the discharge products in the lithium-oxygen and lithium-sulfur batteries from first-principles calculations

Batteries have become a ubiquitous daily necessity, which are popularly applied to mobile phones and electric vehicles according to their size. Improving the battery cycle life and storage is important, but unexpected discharge products still restrict the upper limit of batter performance such as Li₂O₂, LiO₂, and Li₂S. In this study, we calculated electrons and phonons presenting the basic energy states in crystal using the first-principles calculations. The Li₂O₂ and Li₂S are almost insulating due to the wide bandgap from their electronic structure, and doped-active p-orbital may be one of the pathways to improve crystal conduction due to the tendency of the density of states. The LiO₂ is metallic, and the electronic structure and phonons show that the discharge products have an ionic feature. In addition, the ionic crystal can produce a larger DC permittivity because it possesses macroscopic polarisation. For Li₂O₂ and Li₂S, the Raman peak of the O-O bonding is strong, while the Raman peak of the S-ion is very weak. The enhanced Raman peak of the S-ion presents a possibility to prevent the shuttle effect in Li-S batteries.

Spinel copper–iron-oxide magnetic nanoparticles with cooperative Cu(i) and Cu(ii) sites for enhancing the catalytic transformation of 1,2-propanediol to lactic acid under anaerobic conditions

The synergy between Cu(i) and Cu(ii) sites in spinel CuFeO_x magnetic nanoparticles contributes to the significant enhancement in catalytic 1,2-propanediol transformation into lactic acid.

Heterostructures of doped graphene and MoX2 (X = S and Se) as promising anchoring materials for lithium–sulfur batteries: a first-principles study

The heterostructures composed of a MoX₂ (X = S or Se) nanosheet and doped graphene with B or N exhibit superior anchoring effects for soluble Li₂S_n species.