Thermodynamic properties of sodium trititanate (Na2Ti3O7) at high temperature (298.15-1403 K)

Sodium-ion batteries (NaIBs) have attracted extraordinary attentions as a promising scalable energy storage alternative to current lithium-ion batteries (LIBs), owing to their natural abundance and low costs. Sodium trititanate (Na 2 Ti 3 O 7 ) is a promising material as the material of NaIBs with low potential and high theoretical capacitance. In order to better understand their service performance when utilized in rechargeable NaIBs, studies on thermodynamic properties of Na 2 Ti 3 O 7 are indispensable. However, an extensive literature review revealed that the heat capacity of Na 2 Ti 3 O 7 is established with divergences, especially for high-temperature region. Therefore, the 99.5% purity of Na 2 Ti 3 O 7 powder was first Synthesized through solid-state reaction with sodium carbonate (Na 2 CO 3 ) and titanium dioxide (TiO 2 ) as raw materials. The as-prepared samples were used to measure the heat capacity from 573 to 1323 K which was carried out with multihigh temperature calorimeter (MHTC) 96 line. The temperature dependence of heat capacity was modeled as a function: Cp =255.51073 + 0.06059 T − 3.86912 × 106 T −2 (J mol −1 K −1 ) (298.15 - 1403 K), and then used for computing changes in enthalpy, entropy, and Gibbs free energy. Heat capacity of Na 2 Ti 3 O 7 from 0 to 1403 K was given for future application of Na 2 Ti 3 O 7 in rechargeable batteries.