Ultrastable All-Solid-State Sodium Rechargeable Batteries

The insufficient ionic conductivity of oxide-based solid electrolytes and the large interfacial resistance between the cathode material and the solid electrolyte severely limit the performance of room-temperature all-solid-state sodium rechargeable batteries. A NASICON solid electrolyte Na_3.4Zr_1.9Zn_0.1Si_2.2P_0.8O₁₂, with superior room-temperature conductivity of 5.27 × 10^–3 S cm^–1, is achieved by simultaneous substitution of Zr⁴⁺ by aliovalent Zn²⁺ and P⁵⁺ by Si⁴⁺ in Na₃Zr₂Si₂PO₁₂. The bulk conductivity and grain boundary conductivity of Na_3.4Zr_1.9Zn_0.1Si_2.2P_0.8O₁₂ are nearly 20 times and almost 50 times greater than those of pristine Na₃Zr₂Si₂PO₁₂, respectively. The FeS₂||polydopamine-Na_3.4Zr_1.9Zn_0.1Si_2.2P_0.8O₁₂||Na all-solid-state sodium batteries, with a polydopamine modification thin layer between the solid electrolyte and the cathode, maintain a high reversible capacity of 236.5 mAh g^–1 at a 0.1 C rate for 100 cycles and a capacity of 133.1 mAh g^–1 at 0.5 C for 300 cycles, demonstrating high performance for all-solid-state sodium batteries.