Sodium-rich prussian blue analogue coated by poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as superior cathode for sodium-ion batteries

• Published in: Materials today chemistry 2023-06, Vol.30, p.101540, Article 101540
• Main Authors: Syed Mohd Fadzil, S.A.F., Woo, H.J., Azzahari, A.D., Winie, T., Kufian, M.Z.
• Format: Article
• Language: English
• Subjects: Conductive polymer; Conductivity; Precipitation; Sodium-ion battery; Stationary energy storage system
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2023.101540

Sodium-ion batteries (SIBs) are a promising alternative to complement costly lithium-ion batteries for grid-scale stationary energy storage systems. However, finding a suitable cathode material has been a challenging process mainly due to the large radius of sodium-ion that hinders the process of intercalation. In our previous work, we have successfully synthesized Prussian blue analogue (PBA) via simple single iron source precipitation and low thermal method. However, it suffered poor electrical conductivity. In this work, the as-prepared PBA (high purity, low vacancy (∼2%), and high sodium-ion content) was then coated with various concentrations of conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS) via simple stirring method to aid the electron route. The coated PBA (PB–P5) demonstrates two-fold enhanced conductivity of 2.04 × 10−5 S cm−1 at 30 °C and 1.18 × 10−4 S cm−1 at 100 °C. XRD peaks of coated PBAs show a slight shifting to higher diffraction angle, indicating the changes from rhombohedral-like to cubic structure. The battery capacity retention has also improved from 73.9% (PB–P0) to 82.87% (PB–P5), on account of having PEDOT-PSS to slow down the side reaction between cathode and electrolyte and eventually improve the cycling stability. Additionally, PB-P5 displays the lowest potential separation in cyclic voltammetry (CV) and small charge transfer resistance, Rct value, in which indicating a better electron transfer and enhanced overall conductivity. •The presence of NaCl during synthesis promotes PBA with high Na + content.•Simple stirring with PEDOT-PSS dispersion produces PBA coated with PEDOT-PSS.•PBA undergoes phase transition from rhombohedral-like to cubic after coating process.•The as-prepared coated PBA delivers excellent electrochemical performance due to the improved electronic conduction.