Efficient gel-polymer electrolyte for sodium-ion batteries based on poly(acrylonitrile-co-methyl acrylate)

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Efficient polyacrylonitrile-based gel-polymer electrolyte for sodium-ion batteries was prepared using commercially available copolymer poly(acrylonitrile-co-methyl acrylate), propylene carbonate as plasticizer, and NaClO4 or NaPF6 as electrolyte salts. Specific and molar conductivities were determined at different salt concentrations using the ac impedance technique with reversible rather than blocking electrodes. The cation transference numbers were measured using the potentiostatic polarization technique. The electrolytes showed high room-temperature ionic conductivities up to 1.8 × 10−3 S cm−1 and high cation transference numbers up to 0.89. The conductivity followed the Arrhenius behavior with the activation energy of 12–15 kJ mol−1. The polymer electrolyte was able to sustain over 700 charge-discharge cycles in full sodium-ion cells at room temperature and at −20 °C. The results indicate that polyacrylonitrile-based gel-polymer electrolytes are promising systems to replace liquid electrolytes in future sodium-ion batteries.