• Energy Research

Solid oxide fuel cell (SOFC) is a mature opportunity for producing power energy in remote areas like islands, where access to the electrical grid is not favoured, and gas distribution is the only viable approach. In this context, generally, biogas represents the most convenient fuel resources in these areas. However, the direct use of biogas in SOFCs is still an issue to be solved due to its negative effect on the conventional Ni-YSZ anode. In this study, to overcome this issue, we suggested using a protective layer coated on the anode of a commercial SOFC. A nickel manganite showing mixed ionic and electronic conductivity tailored specifically for this approach was investigated. The preliminary characterisations showed that the formation of a Ruddlesden-Popper (RP) n ¼ 1 structure supporting fine encapsulated particles based on Ni was formed around 800 C in consequence of the reducing environment. The electrochemical experiments carried out for 270 h demonstrated for the coated cell significant stability in the presence of dry biogas, albeit an ageing effect was noticed in the electrical percolation of both cell electrodes. The post mortem analyses revealed an attractive redox property for the nickel manganite, which partially returned to the RP n ¼ 2 phase. Moreover, the absence of carbon deposits on the anode suggests possible applications for this approach.

Abstract An investigation of the electrochemical oxidation of glycerol as alternative to hydrogen and methane in solid oxide fuel cells (SOFCs) based on a noble metal-free anode catalyst was carried out. The anode electrocatalyst consisted of a Ni-modified La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3 (LSFCO) perovskite. After thermal activation, air treatment at 1100 °C followed by reduction at 800 °C in H 2 , Ni was mainly present as ultrafine La 2 NiO 4 particles homogeneously dispersed on the perovskite surface. The thermal activation also caused a modification of perovskite into a lanthanum depleted structure. The thermal reduction at 800 °C determined the occurrence of metallic Ni on the surface. These results were corroborated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). A suitable power density (327 mW cm −2 ) was achieved for the electrolyte supported SOFC fed with chemical-grade glycerol in almost dry condition, i.e. steam to carbon ratio (S/C) of 0.2. The highest electrical efficiency (voltage efficiency) approached 50% at the peak power under mild humidification (S/ C = 0.2). Whereas an increase of water to glycerol ratio, caused a progressive decrease of voltage efficiency at the peak power down to 44% for S/ C = 2.

A properly manufactured intermediate temperature Solid Oxide Fuel Cell (SOFC) can be directly fed by dry biogas, considering also the electrochemical partial and total oxidation reactions of methane in the biogas at the anode. In this way the methane in the biogas is electrochemically consumed directly at the fuel cell without the need to mix the biogas with any reforming gas (steam, oxygen or carbon dioxide).

Currently, society is assisting in transitioning from centralized power generation to distributed power generation [1, 2]. This transition is necessary for various reasons that essentially reside on some fundamental points: 1.The current electric lines can not withstand the energy demand of an increasing number of energy-intensive vehicles, especially for mobility [3]. 2.The ever-increasing availability of small electric generators has created many small electricity producers, and on-site use becomes more advantageous [4]. 3.Technologies concerning electrochemical devices for the production and use of energy are particularly efficient for small sizes [5]. In this scenario, the development of energy conversion devices such as solid oxide fuel cells (SOFC) and devices for the storage of electricity such as solid oxide electrolysis cells (SOEC) and metal-air solid oxide batteries can play a crucial role [6, 7]. Solid oxide cells (SOC) are electrochemical devices capable of converting chemical energy into electrical energy when used as SOFCs and vice versa when operated as SOECs. A similar cell can also be used as cell batteries, allowing electricity storage, depending on the grid demand. The current problem is that such devices cannot be considered sufficiently mature because not enough time has passed from their conceptualization to their demonstration for real uses. Therefore, we are assisting to a proliferation of concepts that simulate their perspectives in a suitable environment. Based on these considerations, this communication reports the ideas and prototypes adopted by our research group to improve the flexibility in the use of fuels (SOFC), the convenience of direct methane production through commercial SOEC cells and the realization of a simple and cheep architecture of metal-air battery.

L'OR4 è composto dai seguenti 4 WP: WP4.1 - Trattamento dei combustibili low carbon per l'alimentazione di celle a combustibile; WP4.2 - Ausiliari per applicazioni navali basati sull'uso di celle SOFC; WP4.3 - Ausiliari per applicazioni navali basati sull'uso di celle HT-PEFC; WP4.4 - Progettazione, realizzazione e dimostrazione di un sistema integrato reformer e cella a combustibile.

Electrochemical devices may potentially solve several issues in various sectors such as production of energy (a combination of thermal and electrical energy), storage (supercapacitors and batteries), and production of fuels from wastes. In the meantime, these technologies have an important role in the commitment of the European Union to transform transport and energy systems as part of a low carbon economy following the Strategic Energy Technologies Plan (SET-Plan). In this scenario, the electrochemical devices offer significant opportunities in increasing efficiency, flexibility and integration due to their specific and intrinsically properties. At the present, there is a significant gap between electrochemical technologies operating at low temperatures (from room temperature to 200 °C) and high temperatures (from 700 °C to 1000 °C). These two groups of technologies are sensibly different one to each other. The relevant characteristics are the high costs of materials for low temperature technologies and high cost for the manufacture and maintenance for high temperature technologies. Another difference concerns with the large sensibility to the poisoning for the low temperatures technologies and the poor flexibility in terms of operation for the high temperatures technologies. These are only few examples of what breakthrough is required. Therefore, the key aspect in this roadmap is the development of new materials. The CNR-ITAE has a long and proven experience in electrochemical devices having contributed to the penetration of these technologies into Europe since the early 1980's. In this seminary will be reported the most recent achievements at CNR-ITAE concerning the low and high temperatures electrochemical cells, including, solid oxide fuel cells, solid oxide electrolyser, solid oxide batteries, polymer electrolyte based fuel cells and electrolyser, polymer membrane based supercapacitors and will be suggested novel approaches in order to mitigate the most common problems affecting these technologies.

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Currently, society is assisting in transitioning from centralized power generation to distributed power generation [1, 2]. This transition is necessary for various reasons that essentially reside on some fundamental points: 1.The current electric lines can not withstand the energy demand of an increasing number of energy-intensive vehicles, especially for mobility [3]. 2.The ever-increasing availability of small electric generators has created many small electricity producers, and on-site use becomes more advantageous [4]. 3.Technologies concerning electrochemical devices for the production and use of energy are particularly efficient for small sizes [5]. In this scenario, the development of energy conversion devices such as solid oxide fuel cells (SOFC) and devices for the storage of electricity such as solid oxide electrolysis cells (SOEC) and metal-air solid oxide batteries can play a crucial role [6, 7]. Solid oxide cells (SOC) are electrochemical devices capable of converting chemical energy into electrical energy when used as SOFCs and vice versa when operated as SOECs. A similar cell can also be used as cell batteries, allowing electricity storage, depending on the grid demand. The current problem is that such devices cannot be considered sufficiently mature because not enough time has passed from their conceptualization to their demonstration for real uses. Therefore, we are assisting to a proliferation of concepts that simulate their perspectives in a suitable environment. Based on these considerations, this communication reports the ideas and prototypes adopted by our research group to improve the flexibility in the use of fuels (SOFC), the convenience of direct methane production through commercial SOEC cells and the realization of a simple and cheep architecture of metal-air battery.

A SOFC anodic cermet composed by Ce0.9Gd0.1O1.95 (CGO) and Ni0.49Cu0.51 alloy has been investigated and optimized for the CH4 electro-oxidation in IT-SOFCs. An appropriate synthesis has been developed to obtain optimal electrochemical properties. The anode is characterized by high surface area and suitable catalytic activity towards oxidation of dry methane. Significant improvements on the performances have been obtained by tailoring bulk and surface composition of the alloy. Polarizations curves have been recorded in the temperature range from 700{degree sign}C to 800{degree sign}C. Impedance spectroscopy measurements have been carried out at different cell potentials. The life- time behaviour in dry methane, and the electrochemical stability have been investigated at 750 {degree sign}C. A variation of the electrochemical properties during continuous operation has been observed and interpreted in terms of anode morphology modifications. No significant carbon deposition has been observed after prolonged operation at 750{degree sign}C in the presence of dry methane and CGO electrolyte.