In traditional batteries, the electrolyte material, which is responsible for shuttling ions between a battery’s anode and cathode, is typically a flammable liquid. While facilitating fast ionic diffusion to enable high-performance batteries, liquid electrolytes present safety, reliability, and longevity concerns. To address these concerns, a solid ion conductor can replace the liquid electrolyte to make all-solid-state batteries, but state-of-the-art solid electrolytes typically have ionic conductivities orders of magnitude less than those of their liquid counterparts. A researcher at NREL has developed new solid-state materials with lower activation barriers for ionic conductivity for next-generation solid electrolyte materials in all-solid-state batteries. This Li6PS5CN argyrodite material may experience dynamic reorientations of the cyanide ions that potentially couple to mobile lithium ions via a paddlewheel mechanism to reduce the activation barriers for ionic conductivity.
Chemically or structurally similar known compounds such as Na3OCN, Na3OBH4, and Li6PS5(BH4) have demonstrated enhanced ionic conductivity due to rotational dynamics. However, these known materials do not exhibit ionic conductivities high enough to be competitive with liquid electrolytes and/or are difficult to synthesize and stabilize. A Researcher at NREL has developed a new argyrodite material and synthetic methods at low temperatures that may enable solution-based fabrication of all-solid-state batteries. This approach simplifies the material’s synthesis and usage and mitigates stability and safety concerns associated with the off-gassing of reactants at high temperatures.
A researcher at NREL has demonstrated that the activation barrier for lithium-ion migration in Li6PS5CN is lower than that of the known champion argyrodite Li6PS5Br. The researcher attributes the lower activation barriers to the softening of the energetic landscape of Li6PS5CN due to the presence of the cyanide ion. Prior to this finding, Li6PS5Br boasted the lowest activation barrier for ionic conductivity in the halide-argyrodite family. The lower activation barrier observed in NREL’s new cyanide argyrodite Li6PS5CN represents a promising development in this family of solid electrolytes and for potential applications in all-solid-state batteries.
To learn more about An Argyrodite-Based Solid Electrolyte with with Lower Activation Barriers for Ionic Conductivity for All-Solid-State Lithium-Ion Batteries, please contact Erin Beaumont at:
Applications and Industries
NREL’s cyanide-argyrodite electrolyte for all-solid-state batteries have the potential to transform electrical energy storage across society, holding far-reaching implications for sustainable energy technologies. Specific applications include
- hand-held devices,
- electric vehicles, and
- grid-scale energy storage.
NREL’s cyanide-argyrodite solid-electrolyte material and methods may enable
- All-solid-state batteries with performances comparable to their liquid-electrolyte counterparts,
- Easier and safer manufacturing methods compared to other halide-argyrodite manufacturing methods, and
- A safer and more durable alternative to liquid electrolytes.