Mixed Ionic-Electronic Conductors Based on Polymer Composites

This chapter outlines the current state of mixed ionic-electronic conducting composite materials, and discusses the latest advances from a didactic point of view. Beginning with the fundamentals, the electronic conducting agent and its nature is described. This section progresses from previously studied inorganic composites to the latest updates in flexible and highly conducting organic systems, where radical and π-conjugated polymers are used. Then, the concept of dopants, which boosts the conductivity of these materials, will be expounded, in addition to the material characteristics depending on their nature (organic based and hybrid architectures). Finally, the electronic and ionic transport are explained. The main characterization techniques are discussed in the following section, highlighting electrochemical impedance spectroscopy. In the last section, the role and scope of these materials in different applications (thermocells, batteries, sensors/transistors and other devices) are explained.