Lithium-sulfur batteries are regarded as the most promising energy
storage system due to their high theoretical capacity (1675 mAh/g) and
natural abundance of elemental sulfur. Nevertheless, the sluggish
reaction of the rate-limiting step Li 2S
2 to Li 2S conversion severely hampers
the practical application of lithium-sulfur batteries. The resolution of
this issue is contingent upon a thorough comprehension of the conversion
mechanism of the rate-limiting step. To this end, we have developed the
two-dimensional VO (1-x)S (1+x) alloy
catalysts by ATAT and have constructed a theoretical model that can
accurately predict the thermodynamic energy barrier of the rate-limiting
step in lithium-sulfur batteries. Our model relates the energy barrier
of the rate-limiting step to the p-band center of the nonmetallic
and the d-band center of the metallic for the VO
(1-x)S (1+x) alloy. This model
facilitates the identification of the VO (1-x)S
(1+x) alloy as a potential cathode catalyst for
lithium-sulfur batteries.