Structure, bonding and ionic mobility in Na–V–P–O glasses for energy storage applications

Na-V-P-O glasses are promising materials for sodium ion batteries, and yet a thorough understanding of their atomic scale behavior has so far been elusive. In this work we leverage structural and electrochemical experiments with first-principles and large-scale machine learning-accelerated molecular dynamics to elucidate quantitatively the interplay among structure, bonding, and ion mobility on space and time scales of unprecedented extensions. We unravel the existence of a broad V coordination distribution together with heterogeneous Na-ion mobility featuring percolation channels. Our results are instrumental in the search for NVP glass optimization for electrochemical applications.