Solid Electrolytes for Sodium Battery

Applications

These materials can be used in a solid-state sodium battery, which can be substituted for most rechargeable batteries (e.g., phones, laptops, electric vehicles).

Problem Addressed

Lithium-ion batteries provide high energy densities and specific energies; however, safety problems arise from the presence of volatile organic solvents. Additionally, previous sodium batteries were incapable of operating at room temperature. These solid-state electrolytes eliminate safety problems by removing the need for volatile liquids and, because of their structure, are capable of achieving high conductivity at room temperature.

Technology

These materials have a conductivity of at least 1.0x10-5 S/cm at 300K, which allows them to work in room temperature sodium based storage devices. The high conductivity at room temperature is achieved through the materials’ spinel structure of the general formula AB2C4 wherein anions C are arranged in a close-packed cubic and cations A and B occupy some or all of the octahedral and tetrahedral sites in a lattice. This structure provides good three-dimensional ion transport. These materials are produced by mixing powder combinations and then heat treating them up to 700oC. There is an inverse relationship between the cooling rate and the conductivity of the material. As such, the preferred cooling rate is no greater than 0.2oC/min.

Advantages

  • Inorganic, solid-state electrolytes
  • High conductivity at room temperature