The Role of Percolation Phenomenon in Organic Mixed Ionic‐Electronic Conductive Films for Energy Storage Applications

Organic mixed ionic‐electronic conductors (OMIECs) that efficiently facilitate both ionic and electronic charge transport, as well as ionic‐electronic coupling, are essential for several technological advancements in next‐generation optoelectronic and energy storage technologies. Herein, the role of the percolation phenomenon in OMIECs for electrical and energy storage applications is investigated. To achieve this objective, metallic titanium nanoparticles (TiNPs) serve as an electronic conductive source, and molecular iodine (I 2 ) acts as an ionic conductive source, both embedded in a polyethylene oxide matrix (PEO) that acts as the host polymer. The electrical conductivity of PEO/TiNPs nanocomposite films increases from 2.31 × 10 −5 to 90.64S cm −1 upon reaching the conductive zone. In contrast, after the incorporation of PEO/TiNPs nanocomposite films with I 2 , the electrical conductivity reaches 266.91S.cm −1 . Additionally, the specific capacitance of the PEO/TiNPs nanocomposite film in the conductive zone is 69.4 F g − 1 , exhibiting an electrical double‐layer capacitance behavior. Introducing I 2 into the PEO/TiNPs nanocomposite film increases the specific capacitance to 91.4 F g − 1 , exhibiting battery‐type behavior. This study provides valuable insights into the design and fabrication of new organic mixed ionic‐electronic conductor film for energy storage applications.