Oriented Porous NASICON 3D Framework via Freeze-Casting for Sodium-Metal Batteries

Sodium-metal batteries are promisingcandidates for low-cost,large-formatenergy storage systems. However, sodium-metal batteries suffer fromhigh interfacial resistance between the electrodes and the solid electrolyte,leading to poor electrochemical performance. We demonstrate a sodiumsuperionic conductor (NASICON) with an oriented porous framework ofsodium aluminum titanium phosphate (NATP) fabricated by the freeze-castingtechnique, which shows excellent properties as a solid electrolyte.Using X-ray computed tomography, we confirm the uniform low-tortuositychannels present along the thickness of the scaffold. We infiltratedthe porous NATP scaffolds with sodium vanadium phosphate (NVP) cathodenanoparticles achieving mass loadings of & SIM;3-4 mg cm(-2), which enables short sodium ion diffusion path lengths.For the resulting hybrid cell, we achieved a capacity of & SIM;90mAh g(-1) at a specific current of 50 mA g(-1) (& SIM;300 Wh kg(-1)) for over 100 cycles with & SIM;94% capacity retention. Our study offers valuable insightsfor the design of hybrid solid electrolyte-cathode active materialstructures to achieve improved electrochemical performance throughlow-tortuosity ion transport networks.

Automated summary

Researchers have developed a sodium superionic conductor (NASICON) as a solid electrolyte for sodium-metal batteries, using freeze-casting technique to create an oriented porous framework of sodium aluminum titanium phosphate (NATP). They achieved high mass loadings of sodium vanadium phosphate (NVP) cathode nanoparticles in the porous NATP scaffolds, resulting in short sodium ion diffusion path lengths. The resulting hybrid cells showed a capacity of around 90mAh g(-1) at a specific current of 50 mA g(-1) (about 300 Wh kg(-1)) with over 94% capacity retention after 100 cycles, indicating improved electrochemical performance.