Designing a sustainable interphases for high-performance All-solid-state sodium batteries

Sodium batteries are emerging as a good option for scaling up energy storage systems because of their abundance and low cost. The development of a high-performance all-solid-state sodium battery alongside a suitable electrolyte-anode interface remains unresolved. In this study, we demonstrate a computation-guided experimental approach to design a sodiophilic interlayer as a sustainable interphase to deal with the large impedance of Alumina solid electrolytes. The alloying reaction and sustainable interphase enhance the interfacial wettability of sodium (Na) on β′′-Alumina solid electrolyte and showed interfacial stability of the Na-Au/β′′-Alumina/Au-Na symmetric cell over 100 h at 0.1 mA cm −2 . Moreover, the Na-Au/β′′-Alumina/Au-Na cell offered a reduced interfacial resistance of 370 Ω cm 2 , which could benefit from minimized redox decomposition of the solid electrolyte (SE), ensuring more durable intimate contact. Na/βʺ-Alumina/P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 (NNMO) full solid battery delivered initial discharge capacity of 59 mA h g −1 and 61 % capacity retention over 100 cycles at 0.1 C (60°C). The Na-Au/βʺ-Alumina/NNMO battery presented an initial discharge capacity of 95 mA h g −1 and 90 % capacity retention over 100 cycles. Finite element simulations were also performed, which reveal that the sustainable Na-Au interphase promotes uniform potential distribution and suppresses interfacial points with an intensified electric field, effectively supporting the experimentally observed improvements in interfacial contact and electrochemical stability. Furthermore, the Na-Au/βʺ-Alumina/NNMO cell exhibits a slight modification in areal-specific resistance, increasing from 700 to 900 Ω cm 2 after 100 cycles. This research presented a sodium metal’s chemical and electrochemical stability with solid electrolytes for all-solid-state sodium batteries.