Predicting stable lithium iron oxysulphides for battery cathodes

Abstract

Cathode materials that have high specific energies and low manufacturing costs are vital for the scaling up of lithium-ion batteries (LIBs) as energy storage solutions. We perform an extensive computational search for iron-based oxysulphides using ab initio random structure searching (AIRSS). Several new oxysulphide phases have been discovered which are predicted to be less than 50 meV/atom from the convex hull. Among the predicted phases, two anti-Ruddlesden-Popper structured materials Li2Fe2S2O and Li4Fe3S3O2 have been found to be attractive as they have high theoretical capacities. With band gaps as low as about 2.0 eV, they are expected to exhibit good electronic conductivities. Climbing-image NEB calculations show that the Li-ion transport in these materials has low activation barriers between 0.3 eV and 0.5 eV. The richness of new materials in the Li-Fe-S-O phase field illustrate the great opportunity in these mixed anion systems for energy storage applications and beyond.

Antiperovskite Superionic Conductors: A Critical Review

“…The Co substitution improves the cyclability, whereas Mn substitution deteriorates the cycling performance. , Theoretical study shows the Li-ion diffusion barrier in (Li 2 Fe)­SO is only 0.32 eV, which may explain its good rate capacity . Li 2 Fe 2 S 2 O and Li 4 Fe 3 S 3 O 2 with anti-RP structure are predicted to have similar voltage as (Li 2 Fe)­SO and fast Li conduction channels …”

“…70,71 Theoretical study shows the Li-ion diffusion barrier in (Li 2 Fe)SO is only 0.32 eV, which may explain its good rate capacity. 72 73 For the Na-ion, although Na-containing analogues (Li 2−n Na n Fe)SO cannot be synthesized through solid-state reaction, Na 2 Fe 2 OS 2 with anti-RP structure can be synthesized through solid-state or mechanochemical synthesis. 74…”

“… 72 Li 2 Fe 2 S 2 O and Li 4 Fe 3 S 3 O 2 with anti-RP structure are predicted to have similar voltage as (Li 2 Fe)SO and fast Li conduction channels. 73 …”