Enhanced capacity and stability of K2FeO4 cathode with poly(3-hexylthiophene) coating for alkaline super-iron battery

Poly(3-hexylthiophene)-coated K2FeO4 (K2FeO4@P3HT) was prepared to enhance capacity and stability of K2FeO4. Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR) and X-ray photoelectron spectra (XPS) were performed to characterize K2FeO4@P3HT. Discharge performance results showed that the Poly(3-hexylthiophene) (P3HT) coating layer enhanced the capacity of the K2FeO4 in 10 mol L−1 KOH electrolyte. K2FeO4@P3HT-1% electrode showed a high discharge capacity of 351 mAh g−1, about 13% increase comparing to the K2FeO4 electrode. Moreover, the stability of K2FeO4 electrode was obviously enhanced by P3HT coating, and the discharge capacity of the electrode which was stored in electrolyte for 6 h was improved to 314 mAh g−1, increasing about 22.6% compared to that of 314 mAh g−1. These desirable properties can be attributed to the in-situ formation of two-layer film on the surface of K2FeO4 crystal, which keep electrolyte from directly contacting with K2FeO4 and reduce the resistance of charge transfer.