Solid-state
sodium-ion batteries employing superionic solid-state
electrolytes (SSEs) offer low manufacturing costs and improved safety
and are considered to be a promising alternative to current Li-ion
batteries. Solid-state electrolytes must have high chemical/electrochemical
stability and superior ionic conductivity. In this work, we employed
precursor and solvent engineering to design scalable and cost-efficient
solution routes to produce air-stable sodium selenoantimonate (Na3SbSe4). First, a simple metathesis route is demonstrated
for the production of the Sb2Se3 precursor that
is subsequently used to form ternary Na3SbSe4 through two different routes: alcohol-mediated redox and alkahest
amine-thiol approaches. In the former, the electrolyte was successfully
synthesized in EtOH by using a similar redox solution coupled with
Sb2Se3, Se, and NaOH as a basic reagent. In
the alkahest approach, an amine-thiol solvent mixture is utilized
for the dissolution of elemental Se and Na and further reaction with
the binary precursor to obtain Na3SbSe4. Both
routes produced electrolytes with room temperature ionic conductivity
(∼0.2 mS cm–1) on par with reported performance
from other conventional thermo-mechanical routes. These novel solution-phase
approaches showcase the diversity and application of wet chemistry
in producing selenide-based electrolytes for all-solid-state sodium
batteries.