Computational design of cathode and cathode-buffer materials for Li₁₄P₂O₃N₆ solid-electrolyte-based all-solid-state lithium-ion battery

Abstract Recent advances in high-voltage all-solid-state batteries (ASSBs) have demonstrated the potential of high-ion-conducting solid electrolytes (SEs) to achieve higher energy density, longer cycle life, and improved safety. However, electrochemical and chemical compatibility issues at the SE/electrode interface remain a critical challenge, often leading to high interfacial resistance and degraded performance. Addressing this requires a fundamental understanding of interfacial reactivity and stability. In this study, we employed first-principles density functional theory calculations of chemical mixing energies/interface reaction energy to investigate the thermodynamics of interface formation and structural evolution between LiPON (Li 14 P 2 O 3 N 6 ) SE and a range of potential Li cathode chemistries. Our analysis identified disordered rocksalt cubic structured Li 2 Mn 0.5 Ti 0.5 O 2 F as a promising cathode material and β -Li 3 PO 4 as an effective buffer layer to further stabilize the interface. To complement the thermodynamic insights, ab-initio molecular dynamics (AIMD) simulation was conducted to assess the kinetic effects on interfacial evolution. The AIMD results revealed decomposition products distinct from those predicted by static thermodynamic models, underscoring the crucial role of kinetics in determining interfacial structure and its impact on charge transfer processes. These findings provide valuable guidance for designing stable, high-performance interfaces in next-generation ASSBs.