Development Of Ceramic Based Anode (Ni/Ysz) and Electrolyte (BCZYG) for Protonic Ceramic Fuel Cells (PCFCS) With Auxiliary Thermal Management Via Phase Change Materials (PCMS) for Fuel Cell Technologies /

Abstract

With the continuous depletion of non-renewable resources and climactic concerns along with ever rising demand of energy, the world has now focused its research on utilization of alternative energy resources opposed to oil, natural gas and coal consumption. The demand and supply gap of energy resulting in power outages and interrupted electric supply further instigates the use of stable and high energy generating resources. The panacea for these issues is the use of protonic ceramic fuel cells (PCFCs) with auxiliary thermal energy storage and management unit which can provide steady, sustainable, high energy output with zero dangerous emissions and maximum energy conservation. In comparison with solid-oxide fuel cells (SOFCs), PCFCs are promising candidates for energy generation since they allow proton conduction in addition to oxygen ion conduction resulting in higher conductivity values and operate at intermediate temperature ranges between 400 ⁰C to 700 ⁰C thereby they are less prone to corrosive and degrading environments unlike SOFCs. The current study consists of development of anode and electrolyte of PCFCs with a secondary thermal management system. In this work, Ni/YSZ based anode material via solid-state route using PVA as pore-former in different weight concentrations (3 wt.% and 6 wt.%) has been synthesized and its effect on microstructure and porosity of the anode was studied revealing that that areal porosity of 12 % and 23 % was achieved with 3 wt.% and 6 wt.% of PVA, respectively. Besides, the phase purity, morphology and elemental analysis of Ni/YSZ based anode after sintering at 1000 ⁰C in Ar and reduction at 550 ⁰C in Ar/H2 was investigated using XRD, SEM, EDS etc. Thermal transformation study of as-dried NiO/YSZ powder was also carried out by TGA/DTA. Moreover, the study involves development of proton conducting BCZYG electrolyte via solid-state and gel-combustion method. Formation of required perovskite based structure, morphology and conductivities of BCZYG samples were studied at different temperatures via XRD, SEM and DC conductivity testing. Pure, homogenous cubic perovskite phase structure for gel-combustion and solid-state synthesized BCZYG was attained at 1300 ⁰C and 1500 ⁰C, respectively with corresponding high conductivity values of 3.20 × 10-4 S.cm-1 and 4.70 × 10-4 S.cm-1 at 650 ⁰C in air. Furthermore, several fatty acids based eutectic phase change materials (PCMs) were developed by mathematical modeling followed by experimentation as auxiliary unit of thermal management for PCFCs. The melting point and latent heat of fusion of the designed PCMs were further studied and compared against theoretically calculated values using DSC analysis. The low temperature range of developed PCMs i.e. 25 - 70 ⁰C proposed that not only they can be exclusively adopted as thermal management system for low temperature fuel cells such as PEMFCs, AFCs etc. but they also exhibit the potential to be employed as additional unit with PCFCs for storing excessive heat in parallel with a high temperature based thermal management unit.