DFT Study on Na-Ion Conducting Solid Biopolymer Electrolyte-Based on Agar-Agar and NaPF6 for Sodium-Ion Batteries

This research article is focused on the structural, electronic, thermal, and vibrational properties of solid biopolymer electrolytes based on Agar-Agar and sodium hexafluorophosphate (NaPF6) salt. Herein, the density functional theory (DFT) technique is used to investigate these properties. The structural analysis provides information about the interactions between Agar-Agar and NaPF6 and hence interaction energy is analysed. Thermodynamic parameters such as Gibbs’ free energy (G), enthalpy (H), entropy (S), and specific heat (Cv) etc. are studied by frequency analysis at normal temperature pressure (NTP) of titled electrolytes. The chemical descriptors of the electrolytes have been studied using the molecular orbital theory (MOT). Molecular electrostatic potential surface (MEPS) demonstrates the three-dimensional molecular charge distribution and illustrates the electron-rich and deficit regions over the whole electrolyte system. Mulliken population analysis (MPA) gives the identification of intramolecular hydrogen bonding. The theoretical infrared (IR) study confirms the formation of the complex system between Agar-Agar and NaPF6 salt. The overall DFT studies of sodium ion-based biopolymer electrolytes have better possibilities for safe sodium-ion batteries.