| Abstract: | Owing to the high theoretical capacity (960 mAh/g and 7557 mAh/cm3, respectively) of the low-price iron metal, iron has a great potential for supplying electricity through its oxidizing process and electrical energy storage. Here, we propose a method to generate a large thermal-to-electrical (TtoE) energy conversion factor with carbon steel electrodes and another method for low-cost electrical energy storage in Fe-ion aqueous batteries. Thermoelectrics are suited to converting dissipated heat into electricity for operating electronics, but the small voltage (~0.1 mV/K) from the Seebeck effect has been problematic. An approach with thermo-hydro-electrochemical effects can generate the large TtoE factor, -87 mV/K with low-cost carbon steel electrodes and a solid-state polyelectrolyte made of polyaniline and polystyrene sulfonate (PANI:PSS). We discovered that the thermo-diffusion of water in PANI:PSS under a temperature gradient induced less (or more) water on the hotter (or colder) side, raising (or lowering) the corrosion overpotential in the hotter (or colder) side and thereby generating output power between the electrodes. Our findings are expected to facilitate subsequent research for further increasing the TtoE factor and utilizing dissipated thermal energy. To integrate renewable energy sources such as solar and wind into the electric grid, a cheap, safe, and reliable battery technology is called for. In this study, we investigate iron-ion batteries with organic material polyaniline (PANI) as a cathode, which is cost-effective and sustainable battery technology. The participation of Fe ions in PANI redox reaction improves the reduction potential (discharge voltage). The long-cycle performance of PANI cathode in Fe-ion aqueous battery promises economic energy storage. We believe this study and further research can reduce the cost of stationary energy storage and promote the development of renewable energy research. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198736 |
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