Stable Interfaces in a Sodium Metal-Free, Solid-State Sodium-Ion Battery with Gradient Composite Electrolyte

Composite electrolytes (CE) combining a ceramic filler and a polymer matrix is an effective way to enhance battery safety. But the increased ceramic filler mass fraction decreases the flexibility, which increases the interfacial resistance. To alleviate interfacial resistance further, a gradient composite electrolyte (GCE) using a Sc, Ge-doped Na3Zr2Si2PO12 (NZSP) as the ceramic filler and poly(ethylene oxide) (PEO) as the polymer matrix is proposed. The outer layer contains a low concentration of ceramic filler to improve interfacial contact, and the central layer contains a high concentration of ceramic filler to inhibit dendrite penetration. This GCE possesses an enhanced conductivity (4.0 x 10(-5) S cm(-1) at 30 degrees C) and a reduced interfacial resistance. Furthermore, the safety was boosted using Sn4P3@CNT/C as the high-capacity anode active material and Na3V2(PO4)(3) (NVP) as the cathode active material. This ultrasafe sodium metal-free, solid-state sodium-ion battery (SSSIB) displays an impressive cycling performance.

Automated summary

The use of gradient composite electrolyte with high ceramic filler concentration to inhibit dendrite penetration and low concentration for improved interfacial contact enhances battery conductivity and reduces interface resistance. Additionally, the safety of the battery is further boosted using specific materials for the anode and cathode, resulting in an impressive cycling performance for the ultra-safe solid-state sodium-ion battery.