LITHIUM SECONDARY BATTERY HAVING HIGH ENERGY DENSITY

The present disclosure relates to a lithium-sulfur battery comprising: an electrode assembly, an electrolyte, and a case accommodating the electrode assembly, wherein the electrode assembly comprises a positive electrode comprising a sulfur-carbon composite, a negative electrode and a separator disposed between the positive electrode and the negative electrode, wherein the lithium-sulfur battery fulfills the following requirement of equation 1: S X = S PE / S EL / S , wherein SPE is the sulfur (S) loading amount of the positive electrode as a mAh/cm value, SEL/S is the weight ratio of the electrolyte and sulfur (S) as a dimensionless value, and wherein SX is the sulfur (S) loading amount of the positive electrode per ratio of electrolyte and sulfur, and SX is 1.4 mAh/cm or higher, preferably in a range between 1.4 and 10 mAh/ cm, or wherein the lithium-sulfur battery contains a compound comprising three or more characteristic diffraction angle peaks (2θ values) selected from the following: 7.1 ± 0.2°, 9.0 ± 0.2°, 9.4 ± 0.2°, 9.6 ± 0.2°, 9.9 ± 0.2°, 10.0 ± 0.2°, 10.4 ± 0.2°, 11.0 ± 0.2°, 11.6 ± 0.2°, 12.1 ± 0.2°, 13.3 ± 0.2°, 14.5 ± 0.2° and 15.0 ± 0.2° in the X-ray diffraction (XRD) pattern at DOD 15% to DOD 80%. Furthermore, a method for evaluating the energy density of a lithium-sulfur battery.