Multi-Doping Exploration of (Sb, Bi and Ba) by First Principles on Ordered Zn–Si–P Compounds as High-Performance Anodes for Next-Generation Li-Ion Batteries

Abstract

Chalcopyrite ZnSiP2 has emerged as a promising anode material for next generation Li-ion-based batteries due to its high theoretical capacity. First principles multiple-dopant effect computations were made on the structural, electronic, magnetic, and thermodynamic responses for chalcopyrite ZnSiP2(1−x)Sbx, ZnSiP2(1−x)Bix, Zn(1−x)BaxSiP2, and Zn1−xBaxSiP2(1−x)Sbx, using both the norm conserving, ultra-soft pseudopotentials with generalized gradient approximation (GGA+PBE) and the main frame of density functional theory. Lattice coefficient volume, bulk modulus, formation energy, and total energy of host materials were computed and compared with experimental and theoretical results. Energy band gap for the pure chalcopyrite ZnSiP2 system (1.4 eV) matches previous data and validates the accuracy of current calculations as doping concentration (x = 0.6, 0.9, and 0.12) of (Sb, Bi, and Ba) at Zn and P sites increases. The corresponding band gap decreases, resulting in greater enhancement in electronic conductivity. Finally, the phonon dispersion relation, phonon density of states, vibration frequencies of phonon, Gibbs free energy, enthalpy, entropy effect, and Debye temperature (θ D) were estimated to confirm the thermodynamic stability of both pure and doped systems. These investigations are predicted to contribute a deeper sympathy of the doping effects on ZnSiP2, facilitating further advancements in anode materials design for Li-ion batteries.