Structural and electronic properties of solid-state (LiMPO4∣γ-Li3PO4)[010] electrochemical interface (M = Fe and Co)

First principles density functional calculations are carried out to investigate the structural, electronic, and electrochemical properties of the bilayered nanocomposite, which is composed of LiMPO4 (M = Fe and Co) as a positive electrode and γ-Li3PO4 as a solid-state electrolyte. The calculated interfacial energy reveals that the Li-O atomic layer terminated (010) LiMPO4 surface gives better stability than its Fe-O layer termination, for constructing the solid state interface with γ-Li3PO4. Further, structural optimization shows that inter-layer distances at the interface and surface of the electrolyte are increased ≈0.1 and 0.06 Å, respectively, from its bulk value. Moreover, electronic structure calculations infer that the energy of top most occupied level in the electrode strongly depends on its thickness, whereas, this energy is almost constant for different thick electrolytes. Thus, our study suggests that by varying the thickness of LiMPO4-electrode, Li-ion vacancy formation and electrochemical performance of the nanocomposite can be altered favourably.