First-principles calculations into LiAl(NH2)4 and its derivative hydrides for potential sodium storage

Abstract In this work, we have employed the first-principles quantum physics method to investigate the light-metal based LiAl(NH2)4 and its modified compounds as conversion electrode materials for sodium-ion batteries on the basis of state-of-the-art Density Functional Theory. The pure LiAl(NH2)4 possesses an average voltage of 0.294 V (versus Na+/Na0) and a theoretical specific capacity of 1093.77 mA h g-1 for sodium storage. Among the modified materials, the Li4AlB3(N4H8)4 has the most excellent electrochemical properties with a theoretical specific capacity of 1249.57 mA h g-1 and a low average voltage of 0.087 V (versus Na+/Na0) for potential anode applications. The diffusion behavior of Na-ion is also improved in Li4AlB3(N4H8)4 whether at 300K or at 400K, which indicates the prospective rate capability. The diffusion coefficient of Na-ion is obviously increased to 3.667×10-9 m2 s-1 (in modified material) from 1.500×10-9 m2 s-1 (in pristine material) at 400K. The diffusion of Na-ion is calculated to be very fast in Li4AlB3(N4H8)4 with a kinetic barrier of 0.31 eV. This work will provide impetus to the quantum design and experimental development of complex hydride materials for metal-ion battery applications.