In the current energy transition context, large-scale underground facilities, such as salt caverns, able to deliver high flow rates, represent the most promising viable massive energy storage system that can respond efficiently to the flexibility needs of the renewable energy. In order to predict the performances of these facilities, while ensuring a high safety level over long time periods, the reservoir behavior must be studied by higher accuracy approaches. Based on a multiphase multicomponent approach, a cavern thermodynamic model, that can be used in field applications, is derived for this purpose. Particular attention is given to salt caverns where the stored fluid can be in contact with the brine. All the balance equations that govern the well that connects the cavern to the ground surface and the surrounding formation are presented. An illustrative example, showing the necessity of taking into account the thermo-mechanical aspects when considering the cavern thermodynamic behavior under cyclic loading conditions, is also discussed.