Solid electrolyte, and method for producing same

A sulfide-based solid electrolyte comprising a compound represented by the following Chemical Formula 1 or Chemical Formula 2:

• LixZnyPzS6 [Chemical Formula 1]
• wherein 1≤x≤4, 0<y≤2, and 0<z≤3;
• Li2+2kZn1−kP2S6 [Chemical Formula 2]
• wherein 0≤k<1;
• wherein the compound has a crystal structure satisfying the following conditions (a)-(c):
• (a) a space group that belongs to P31m (No. 162);
• (b) unit cell parameters of a=6.03±0.5 Å and c=6.59±0.5 Å;
• and
• (c) crystallographic coordinates of cations occupying 2c, 2d and 2e coordinates in a unit cell with a site occupancy of each coordinate of larger than 0 and equal to or less than 1, and a crystallographic coordinate of anions occupying 6k coordinate in a unit cell with a site occupancy of 6k of larger than 0 and equal to or less than 1, wherein each of the coordinates represents the following:
• 2c (⅓, ⅔, 0);
• 2d (⅓, ⅔, ½);
• 2e (0, 0, z), wherein 0.30≤z≤0.33;
• and
• 6k (x, 0, z), wherein 0.325≤x≤0.35 and 0.23≤z≤0.28.