Electrolyte Sieving Chemistry in Suppressing Gas Evolution of Sodium-Metal Batteries.

The sodium (Na)-metal batteries hold great promise as a sustainable technology owing to the high element abundance and low cost. However, the generally used carbonate electrolytes remain highly reactive towards Na metal, leading to flammable gas evolution. Here, we propose an electrolyte sieving strategy to separate anion-mediated ion-pairs from dilute electrolytes by introducing a 3A zeolite molecular sieve film. The anion-mediated ion-pair firstly weakens the electron-withdrawing property of the cation, which effectively suppresses the gassing. In addition, the sieved electrolyte promotes the formation of robust inorganic-dominated solid electrolyte interphases. Therefore, it contributes to stable Na plating/stripping in Na|Al half cells with Coulombic efficiency maintaining at 98.5 % and a long service life of 800 cycles in full cells. Moreover, the electrode stability is well preserved even under harsh conditions of high temperature and ester-based electrolytes with higher reactivity.