Polypyrrole-Modified Prussian Blue Cathode Material for Potassium Ion Batteries via In Situ Polymerization Coating

after 500 cycles. The capacity decay rate was 0.03% per cycle. Detailed characterization showed a lack of phase transition during the charge and discharge processes and determined that K ions were not completely extracted from the monoclinic structure, possibly contributing to the excellent cycling stability. This simple surface modification method represents a promising means of mitigating issues currently associated with PB-based cathodes for PIBs.