Gorivne celice s trdnim elektrolitom : magistrsko delo

Bertalanič, Žiga (author), Kosec, Borut (mentor), Malič, Barbara (comentor)

Podnebni in strateški cilji Evropske skupnosti zahtevajo postopen, a odločen umik neobnovljivih energentov. Prav tako je cilj, da obstoječe pogonske agregate zamenjamo z učinkovitejšimi in okolju prijaznejšimi. Termični motorji, na primer motorji z notranjim izgorevanjem, poleg ogljikovega dioksida v okolje prispevajo še znaten delež dušikovih oksidov ter prašnih delcev. Kemijsko energijo moramo na ekološko nesporen način pretvoriti v električno energijo, ki jo nadalje z velikim izkoristkom uporabimo za pogon vozil. S transportom energentov po plinovodih do uporabnikov, kjer pretvorimo kemijsko energijo v električno, se izognemo preobremenjevanju električnega omrežja ter omogočimo hitro polnjenje zaloge goriva. Gorivne celice omogočajo učinkovito pretvorbo kemijske energije v električno. Gorivne celice s trdnim elektrolitom (angl.: Solid Oxide Fuel Cells – SOFC) oziroma visokotemperaturne gorivne celice imajo med različnimi izvedbami celic največji izkoristek in njihovo delovanje je najmanj občutljivo na kakovost goriv. Gorivne celice s trdnim elektrolitom so najpogosteje zložek keramičnih plasti anode, trdnega elektrolita in katode ter kovinskega prevodnika, ki povezuje posamezne plasti. Na katodi poteka redukcija kisika v kisikove anione, ki potujejo skozi trdni elektrolit do anode, kjer poteče reakcija med kisikovimi anioni in vodikom. Običajno so debeline plasti anode, trdnega elektrolita in katode okrog 10 mikrometrov, plasti kovine so milimetrske debeline. Gorivne celice s trdnim elektrolitom sem pripravil v obliki večplastnih struktur. Anodo sem pripravil kot večplastno strukturo s postopkom nalivanja suspenzije zmesi prahov nikljevega oksida in cirkonijevega oksida, modificiranega z itrijevim oksidom (YSZ), in laminacijo posameznih plasti do želene debeline. Preostale elemente gorivne celice, trdni elektrolit YSZ, katodo lantanov stroncijev kobaltit ferit in zaščitno plast cerijev oksid, dopiran z gadolinijevim oksidom, sem nanesel s sitotiskom. Zložke sem sintral v peči do temperature 1200 °C na zraku. Na podlagi mikrostrukturne analize z vrstičnim elektronskim mikroskopom sem zaključil, da med posameznimi plastmi ni prišlo do opaznih interakcij oziroma do pojava razpok.

• Language: Slovenian
• Keywords: Gorivne celice, gorivne celice s trdnim elektrolitom (SOFC), elektrolit, anoda, katoda
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: Ž. Bertalanič
• Year: 2024
• Number of pages: XXIV, 49 str.
• PID: 20.500.12556/RUL-155835
• UDC: 669
• COBISS.SI-ID: 193678339
• Publication date in RUL: 23.04.2024

Secondary language

• Language: English
• Title: Solid oxide fuel cells : master's thesis

Abstract

The climate and strategic goals of the European Union require a gradual yet decisive transition away from non-renewable energy sources. Existing power units should be replaced with more efficient and environmentally friendly alternatives. Thermal engines, for example internal combustion engines, contribute a significant amount of nitrogen oxides and particulate matter to the environment in addition to carbon dioxide. We should convert chemical energy into electrical energy in an ecologically indisputable manner and use it with high efficiency to power the vehicles. By transporting energy carriers through pipelines to the point of use, where chemical energy is converted into electrical energy, we avoid overloading the electrical grid and enable rapid fuel replenishment. Fuel cells enable the effective conversion of chemical energy into electrical energy. Solid oxide fuel cells (SOFCs) or high-temperature fuel cells have the highest efficiency among versatile cell designs, and their operation is the least sensitive to fuel quality. Solid oxide fuel cells most frequently consist of a composite of ceramic layers for the anode, solid electrolyte, and cathode, along with a metal conductor that connects the individual layers. At the cathode, oxygen is reduced to oxide anions, which travel through the solid electrolyte to the anode, where a reaction occurs between the oxide anions and hydrogen. Typically, the thicknesses of the anode, solid electrolyte, and cathode layers are around 10 micrometers, and the metal layers are about millimeter thick. I prepared fuel cells with a solid electrolyte in the form of multilayer structures. The anode was formed by tape-casting the suspension of a powder mixture of nickel oxide and zirconium oxide stabilized with yttrium oxide (YSZ) into sheets and laminating them to the desired thickness. The remaining elements of the fuel cell, the YSZ solid electrolyte, the lanthanum strontium cobaltite ferrite cathode and the protective layer of cerium oxide doped with gadolinium oxide were screen printed. The multilayer structure was sintered at a temperature of 1200 °C in air. The scanning electron microscopy analysis revealed that there were no noticeable interactions between individual layers or the appearance of cracks between individual layers.

• Keywords: Fuel cells, solid oxide fuel cell (SOFC), electrolyte, anode, cathode