Abstract: The present disclosure relates to a halide solid electrolyte that exhibits a more improved ionic conductivity, excellent stability and flexibility, and the like, a method for producing the same, and a secondary battery comprising the same. The halide solid electrolyte may be represented by the Formula: Li(6?4a+b)MaX6?bSb.

Abstract: Disclosed is a method for designing the composition of a layered structure of Li3YCl6 compound exhibiting enhanced ionic conductivity, which provides a method for designing the composition of a lithium yttrium halide solid electrolyte with a hexagonal close-packed structure, the method being executed by a processor, the method including: calculating possible diffusion paths for lithium ions to migrate an adjacent octahedral site in the a-b plane in each consecutive layer constituting a unit cell with a hexagonal close-packed structure; calculating the activation barrier energy for lithium ion diffusion for each of the calculated diffusion paths; and determining the occupancy of yttrium within the unit cell to form a percolation state where diffusion paths with a low calculated activation barrier energy are connected within the unit cell.

Abstract: Disclosed is a novel halide-based solid electrolyte composition exhibiting enhanced ionic conductivity, wherein the solid electrolyte composition comprises a lithium yttrium halide with a hexagonal close-packed structure, and when the occupancy of metal ions is defined as the number of metal ions relative to the number of metal ion sites within two consecutive layers constituting a unit cell with a hexagonal close-packed structure in the halide, the sum of the occupancies of metal ions within the two layers is 0.888 or less.