Cho, Kyu T.
M.S. (Master of Science)
Department of Mechanical Engineering
Mechanical engineering; Chemistry; Engineering
Renewable energy based on solar and wind resources is getting intense attention to solve issues of the conventional fossil-based energy of which amount is limited and which is the major source to cause environmental pollution. But, due to its intrinsic dependence on weather condition, the produced energy is not stable to be directly utilized. Therefore, a system called energy storage system is required which can store the energy generated precariously and provide it stably to the places on demand. Li-ion battery is currently the most popular electrical energy storage system, and it is being applied to most electricity-powered systems from portable electronic devices to automotive system and grid-level energy system. However, it has challenging issues associated with high system cost, safety issues, and low energy density (i.e. short driving range), and thus the new energy storage system needs to be developed to solve those issues of the conventional battery system. Aluminum-air battery, which requires only inexpensive aluminum strips and free oxygen from air as reactive species (i.e. fuel), has been studied actively since 1960s due to the excellent benefits of cost, high theoretical voltage (2.7V), high specific energy (2.8 kWh/kg, almost 7 times greater than Li-ion battery) and high volumetric capacity (8046 mAh/cm3). But the Al-air battery could not be fully applied due to the challenging issues such as (1) formation of oxide layers on the Al surface causing Al to be deactivated and (2) parasitic self-corrosion of Al. Because of the protective oxide layer on aluminum, the open circuit cell potential is decreased (i.e. the actual cell voltage is considerably lower than theoretical cell voltage) and “delayed response” (i.e. the time lag in reaching maximum voltage when the circuit is closed) is induced. The electro- deposition of aluminum ions (i.e. cell charge condition) is not feasible in an aqueous alkaline electrolyte due to the hydrogen evolution, causing aluminum-air battery to be used as a primary energy storage device (i.e. non-rechargeable battery). A detailed study and analysis of aqueous electrolytes was conducted to understand the key parameters to control the hydrogen evolution with aqueous and non-aqueous solutions having various concentration of potassium hydroxide. The effect of saline electrolyte and additives on H2 evolution was also studied to evaluate the effect of different pH conditions and additives. The battery cell performance was tested to study the mass-transfer limited overpotential with various cell structures: a conventional Swagelok cell where reactants transport in diffusion mode and flow-cell structure where reactants transport in diffusion and convective mode. The ohmic-transfer limited loss was studied with various membranes including KOH-treated nafion membrane, anion membrane, and porous membrane. Results of this study will present key factors in reducing side reactions and increasing cell performance to advance understandings and knowledge of this emerging cell system.
Bhonge, Kaustubh, "Study of aqueous electrolytes and parameters affecting the performance in aluminum-air batteries" (2017). Graduate Research Theses & Dissertations. 5111.
vii, 53 pages
Northern Illinois University
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