A non-aqueous electrolyte solution and a lithium secondary battery including the same are disclosed herein. In some embodiments, a non-aqueous electrolyte solution includes an HF indicator, and a pouch-type lithium secondary battery includes a pouch case having a transparent identification part for observing the interior of the pouch-type battery from the exterior of the pouch case. Defects generated during the preparation of the secondary battery may be visually identified based on the presence of hydrofluoric acid without disassembling the pouch-type battery.