Ion-Gated Transistors Based on Metal Oxides—From Electronics to Iontronics and Li-Iontronics

Ion-gated transistors (IGTs) employ ionic gating media (e.g. ionic liquids, polymer electrolytes, aqueous saline solutions) to modulate the density of the charge carriers in the transistor channel. The high capacitance featured by IGTs permits, among others, to use them in the study of insulator-to-metal transitions. Considering IGT-based technologies, not only IGTs operate at voltages as low as 0.1-1 V but they can also feature mechanical flexibility, printability and easy integration with chemo- and bio-sensing platforms.<br/>Metal oxides are transistor channel materials interesting for their processability in air, at low temperature. They also constitute the basis for battery cathode materials in lithium-ion batteries.<br/>In this contribution, we will discuss the opportunity IGTs offer to be employed as in situ diagnosis tools to evaluate the state of health of Li-ion batteries from the point of view of the evolution of the electronic properties of the battery cathodes (e.g. charge carrier density, electronic charge carrier mobility) as a function of the electrode (lithiation and de-lithiation) cycling conditions.