A P2‐Type Layered Superionic Conductor Ga‐Doped Na2Zn2TeO6 for All‐Solid‐State Sodium‐Ion Batteries

Here, a P2‐type layered Na2Zn2TeO6 (NZTO) is reported with a high Na+ ion conductivity ≈0.6×10−3 S cm−1 at room temperature (RT), which is comparable to the currently best Na1+nZr2SinP3−nO12 NASICON structure. As small amounts of Ga3+ substitutes for Zn2+, more Na+ vacancies are introduced in the interlayer gaps, which greatly reduces strong Na+–Na+ coulomb interactions. Ga‐substituted NZTO exhibits a superionic conductivity of ≈1.1×10−3 S cm−1 at RT, and excellent phase and electrochemical stability. All solid‐state batteries have been successfully assembled with a capacity of ≈70 mAh g−1 over 10 cycles with a rate of 0.2 C at 80 °C. 23Na nuclear magnetic resonance (NMR) studies on powder samples show intra‐grain (bulk) diffusion coefficients DNMR on the order of 12.35×10−12 m2 s−1 at 65 °C that corresponds to a conductivity σNMR of 8.16×10−3 S cm−1, assuming the Nernst–Einstein equation, which thus suggests a new perspective of fast Na+ ion conductor for advanced sodium ion batteries.