Abstract: To compare the performances of Rankine-Carnot batteries with different energy storage methods, thermodynamic models of the heat storage Rankine-Carnot battery and cold storage Rankine-Carnot battery were developed, respectively. The energy efficiency and exergy efficiency of the two systems under the same parameter conditions were compared and analyzed. The results of energy analysis show that: the round-trip electrical efficiency of Rankine-Carnot batteries with different energy storage methods is jointly determined by the charging cycle efficiency and discharging cycle efficiency. For the heat storage Rankine-Carnot battery, its round-trip electrical efficiency decreases by 17.99% as the heat storage temperature increases by 10 K, and decreases by 12.06% as the ambient temperature increases by 10 K. For the cold storage Rankine-Carnot battery, its round-trip electrical efficiency increases by 15.82% as the cold storage temperature increases by 10 K, and decreases by 22.69% as the ambient temperature increases by 10 K. The results of exergy analysis show that: the exergy efficiency of the heat storage Rankine-Carnot battery decreases by 2.62% as the heat storage temperature increases by 10 K, and decreases by 4.90% as the ambient temperature increases by 10 K. The exergy efficiency of the cold storage Rankine-Carnot battery increases by 1.91% as the cold storage temperature increases by 10 K, and decreases by 7.82% as the ambient temperature increases by 10 K. The results of parameter sensitivity analysis show that under the same cycle temperature difference, both the energy evaluation indicators and exergy evaluation indicators of the heat storage Rankine-Carnot battery are higher than those of the cold storage Rankine-Carnot battery. Moreover, compared with the discharging cycle, the performance parameters of the charging cycle are more sensitive to changes in parameter conditions.