Fabricating and analyzing liquid and polymer electrolytes for sodium-ion batteries

The abundance and the cost-effectiveness of sodium resources have made sodium-ion batteries (SIBs) viable alternatives to lithium-ion batteries. Developing low-cost and high-performance electrolytes is one of the key areas for the advancement of SIB technology. The highly conductive liquid or solid electrolytes have the potential for practical sodium-ion battery applications. Long-term stability, alternative polymers, and full-cell integrations are other avenues that need further research to improve scalability and performance for SIBs. This research covers preparing and evaluating liquid and polymer electrolytes, with a focus on ionic conductivities. Liquid electrolytes were prepared by the dissolution of different sodium salts including NaCl, Na2S, Na2SO3, and NaF in methanol, water, DMF (dimethyl formamide), n-propanol, and DMSO (dimethyl sulfoxide) solvents, in a concentration range from 0.01 M to 0.1 M. It is aimed to investigate the impacts of the solubility, polarity, and concentration on the ionic conductivities. Polymer electrolytes were prepared using the solvent casting technique. The films contained NaCl as the salt and PEO (polyethylene oxide) as the polymer host. The impacts of the two solvents, methanol and DMF, with and without plasticizer EC (ethylene carbonate) on the ionic conductivity of the polymer electrolytes were analyzed. The study validates that optimizing solvent and additive selection are paramount in developing high-performance electrolytes for SIBs.