Brighi, MatteoMurgia, FabrizioLodziana, ZbigniewSchouwink, PascalWolczyk, AnnaCerny, Radovan2018-12-252018-12-252018-12-252018-11-1510.1016/j.jpowsour.2018.09.085https://infoscience.epfl.ch/handle/20.500.14299/153185WOS:000452584900002The novel compound Na2-x(CB11H12)(x)(B12H12)(1-x) shows a fast ionic Na conductivity of 2 mS cm(-1) at room temperature, reaching the superionic regime above 333 K. A low activation energy of 314 meV, in a thermodynamically and electrochemically stable structure, suggest its usage as a potential solid electrolyte in future all solid Na-ion batteries. Density functional theory simulations indicate the heterovalent anionic mixing to be the responsible in stabilizing a bcc structure, which allows a facile Na+ diffusion already at room temperature. Cyclic voltammetry measurement with a tailored setup for solid-state electrolytes reveals a wide operating window (up to 4.1 V vs. Na+/Na). The symmetrical cell featuring Na-Sn alloy-based electrodes shows reversible Na+ shuttling with limited polarization after more than 700 operating hours.Chemistry, PhysicalElectrochemistryEnergy & FuelsMaterials Science, MultidisciplinaryChemistryMaterials Sciencesolid electrolytesstructural disorderna-ion conductivitysolid state cyclic voltammetrycloso-hydroborate carba-hydroborate mixsodium superionic conductionlithiumreorientationsprinciplesphasetext::journal::journal article::research article