Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)–polymer composites as functional cathode binders for high power LiFePO4 batteries

Electroactive conductive composites based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and co-binding polymers—poly(ethylene oxide) (PEO) or sulfonated poly(phenylene oxide) (SPPO)—have been evaluated as conductive binders for LiFePO₄ cathodes in Li-ion batteries. We have demonstrated that PEDOT:PSS–PEO and PEDOT:PSS–SPPO facilitated charge transfer for high rate application (discharge capacity up to 115 mAh g⁻¹ at 3C). The thicker cathodes containing extra high loading of commercial LiFePO₄/C (95 wt%, 19 mg cm⁻²) have exhibited specific capacity of up to 120 mAh g⁻¹ and areal capacity of up to 2 mAh cm⁻² at 1C, several times higher as compared to the earlier reported LiFePO₄/PEDOT cathodes. While the application of PEO in PEDOT:PSS composites is restricted to sulfolane-based electrolytes due to solubility limitations, the PEDOT:PSS–SPPO-based cathodes can be used with conventional carbonate electrolytes, showing good stability and cyclability.