Superior interfacial stability and conductivity of B-doped LiPON electrolyte for LiCoO2 electrode in solid-state lithium batteries

Lithium cobaltate (LiCoO2) is a promising electrode material in applications of high voltage all-solid-state batteries (ASSBs). However, resistance exists at the interface between LiCoO2 and solid electrolyte still hinders further development of LiCoO2-based ASSBs, and little is known on electronic state and diffusion of ions from atomic-level. In this work, first-principles calculations and ab initio molecular dynamics (AIMD) are applied to investigate interfacial thermodynamic stability, electronic structure and diffusion of lithium between LiCoO2 and B-, Al-, As-doped LiPON for all-solid-state batteries. Based on calculations of interfacial energies and density of states, it is inferred that the LiCoO2/LiPON interface is thermodynamically stable. By the energies related to interfaces and electronic structures, it is demonstrated that the ability on interfacial binding and electronic property are enhanced after doping B, Al and As in LiPON, in particular, LiCoO2/LiBPON system shows the optimal interfacial stability and conductivity. AIMD simulations show that the doping in LiPON can also contribute an improved diffusion property of lithium, and the diffusion of lithium in LiCoO2/LiBPON system is the fastest at 300 and 400 K.