Free-standing poly(3,4-ethylenedioxythiophene) (PEDOT)–LiFePO4 composite films were successfully prepared by dynamic three phase interline electropolymerization (D3PIE). These films were used without further modification as the positive electrode in standard lithium ion batteries. As such, this new process eliminates all electrochemically inactive materials (carbon, polymer binder and current collector) used in conventional composite cathodes. The PEDOT–LiFePO4 composite film offers a discharge capacity of 75 mAh g−1 at the C/10 rate and high capacity retention at the C/2 rate. When reporting this value to the relative amount of LiFePO4 in the PEDOT-LiFePO4 composite film, the discharge capacity reached 160 mAh g−1, close to the theoretical maximum value (170 mAh g−1). As such, this approach yield highly functional hybrid free-standing conductive polymer/active material composite cathode with controllable size and structure.