Ragone plots (energy-power relations) and discharge efficiency-power relations are important for characterizing energy storage (ES) devices, as they contain the information on the maximum power and the available energy. In this theoretical study, these two characteristics and the losses per energy are derived in the framework of endoreversible thermodynamics for ideal electric and thermal ES systems with different dependencies of their intensive thermodynamic variables (potentials, temperatures) of the reservoirs on the extensive state variables (electric charge, heat) that quantify their state of charge. While for battery and latent heat storage device, the normalized Ragone plot is equal to the discharge efficiency-power relation, the two characteristics differ for electric capacitor and sensible heat storage device due to their intrinsically limited depth of discharge at constant power. Due to the decrease of the exergy of heat at decreasing temperature, the discharge efficiency of the ideal sensible heat storage device exhibits a local maximum at a finite power value.

Ragone图（能量-功率关系）和放电效率-功率关系对于表征储能（ES）设备非常重要，因为它们包含有关最大功率和可用能量的信息。在此理论研究中，这两个特性和每单位能量的损失是在理想电和热电系统的内可逆热力学框架内得出的，理想的电和热电系统具有不同的储集层热力学变量（势能，温度）对广泛的状态变量的依赖关系（电荷，热量）来量化其电荷状态。而对于电池和潜热存储设备，归一化的Ragone图等于放电效率与功率的关系，电容器和显热存储设备的这两个特性不同，这是因为它们在恒定功率下固有的放电深度有限。由于在降低的温度下热能的减少，理想的显热存储装置的放电效率在有限的功率值处表现出局部最大值。