Theoretical study of the properties of Nb-doped Li3YbCl6 solid-state electrolytes

Halide solid-state electrolytes have recently received significant attention because of their superior properties of electrochemical stability and high ionic conductivity. Experimentally, doping by tetravalent cations (such as Zr⁴⁺ and Hf⁴⁺) is usually adopted to further improve the ionic transport properties. To explore more dopant possibilities, we have thoroughly investigated the stabilities, ionic conductivities and electrochemical properties of pentavalent Nb-doped Li₃YbCl₆ by using first-principles calculations. Our calculated results have revealed that the most stable phase of Nb-doped Li₃YbCl₆ might be the structures with an orthorhombic space group. Also, it can be expected that a small amount of Nb doping can increase the ionic conductivity with a slightly decreased width of the electrochemical window of Li₃YbCl₆. This work demonstrates the potential of pentavalent cation doping for improving the performance of halide solid-state electrolytes.