Thermodynamic data of a promising cathode material NaV6O15 and its synthesis/decomposition thermodynamic analysis

Abstract

Sodium-ion batteries have emerged as a promising alternative to lithium-ion batteries due to their lower cost and similar electrochemical properties. The development of high-capacity and long-life electrode materials is crucial for advancing sodium-ion battery research. A significant amount of research has been conducted on the electrochemical properties of NaV6O15, however, there remains a dearth of data on its thermodynamic properties. Herein, NaV6O15 was synthesized using the solid-phase sintering method and thoroughly characterized. Thermodynamic data in the temperature ranges of 298.15–900 K, 15–303 K, and 573–873 K were determined using the Neumann-Kopp rule, low-temperature physical property measurement system, and MHTC 96 line, respectively. The heat capacity equation of NaV6O15 was derived and its enthalpy, entropy, and Gibbs free energy (298.15–800 K) were calculated. Moreover, the thermodynamics of NaV6O15-related formation and decomposition reactions were analyzed. The obtained heat capacity equation of NaV6O15 was Cp=517.05524+0.08612T−1.25053×107T−2(J/mol·K)(298.15∼873K). This study addresses the thermodynamic knowledge gaps of NaV6O15 and provides valuable insights for its preparation and decomposition in manufacturing processes.