Solid‐State Na Metal Batteries with Superior Cycling Stability Enabled by Ferroelectric Enhanced Na/Na3Zr2Si2PO12 Interface

Solid-state metal batteries are attracting unprecedented concern because of their high energy density and safety. However, their service life, especially at high specific density, is hindered by the undesirable reversibility of metal anodes, owing to the inhomogeneous ion distribution and awkward charge transfer dynamics at the electrode/electrolyte interface. In this work, it is well demonstrated that ferroelectric phase BaTiO3 reinforced Na3 Zr2 Si2 PO12 ceramic electrolyte can deconcentrate the distribution of charge transfer and self-accelerate Na+ migration at the Na/Na3 Zr2 Si2 PO12 interface upon cycling, realizing a compact Na deposition morphology together with a high critical current density (1.05 mA cm-2 at ambient conditions). Assembled symmetric cells based on the proposed composite electrolyte render stable cycling up to 1000 h at 0.3 mA cm-2 . Specifically, the all solid-state sodium metal batteries paired with Na3 V1.5 Cr0.5 (PO4 )3 cathode material can deliver a capacity of 95 mAh g-1 at 100 mA g-1 and maintain 84.4% of the initial capacity after 400 cycles. This excellent electrochemical performance clearly confirm the feasibility of the introduction of ferroelectric BaTiO3 to suppress the dendrite nucleation and Na propagation within ceramic electrolyte. This research offers new insight into the rational design of inorganic electrolyte, revealing dendrite-free and long-term all-solid-state sodium batteries.