Fuel Cells最新文献

This paper presents an implementation method of perturbation currents for vehicular proton exchange membrane fuel cell (PEMFC) online electrochemical impedance spectroscopy (EIS) measurements. The topology of the parallel dual-boost DC/DC converter system for the EIS measurement is presented. The DC_dc and DC_ac modules in the converter system implement the DC current and the sinusoidal EIS perturbation current independently. Simulation results show that the proposed perturbation current generation method can be implemented efficiently. In the frequency domain, the current of DC_dc couples to the perturbation current of DC_ac, leading to a reduction in the accuracy of the current amplitude after superposition. The mechanism of current amplitude reduction after superposition is discussed. Feed-forward compensation and fuzzy compensation optimization are proposed for the DC_dc current control. Both compensation algorithms achieve excellent results. A comprehensive framework for evaluating the compensation effect is presented. The evaluation results show that feed-forward compensation has a better advantage in solving the above problems due to its simplicity and less impact on hardware control. Experimental results show that with the optimization algorithm, the input perturbation current increases from 6% to 83% of the theoretical value.

Solid oxide fuel cells (SOFCs) can accept a direct feed of biogas for power generation; however, carbon deposition is a major obstacle to their practical application. When a paper-structured catalyst (PSC) with a dispersion of Ni-loaded flowerlike Ce_0.5Zr_0.5O₂ (Ni/CZ(F)) was applied to the anode of an electrolyte-supported cell (ESC), the open-circuit voltage of the cell directly fed simulated biogas was increased from 0.87 to 0.98 V at 750°C. The rates of cell-voltage degradation and coke formation of the ESC with the Ni/CZ(F)-PSC during 100 h of operation were 4.3% kh⁻¹ and 0.43 mg-C g-PSC⁻¹ h⁻¹, respectively, which were lower than those of an ESC with a Ni-loaded PSC without the CZ(F) dispersion (10.4% kh⁻¹ and 8.1 mg-C g-PSC⁻¹ h⁻¹, respectively). This performance improvement is attributed to the unique porous morphology and high oxygen storage capacity of CZ(F), which can contribute to the prevention of Ni agglomeration and the removal of coke from the catalyst surface, respectively. Thus, the Ni/CZ(F)-PSC can function as a practically applicable reforming domain for an internal-reforming biogas-fueled SOFC.

A simulated interconnect/contact/cathode/cathode support test cell is fabricated to investigate the effectiveness of the high-entropy alloy as the contact material on the microstructure and the performance of the converted spinel-based layer. Although the CuMnNiFeCo alloy powder is selected as the contact precursor, it showed good sinterability after sintering at 900°C for 2 h in air. The electrical performance of the contact layer is evaluated by the area-specific resistance measurement, including isothermal exposure and thermal cycling. The compatibility of the contact layer with adjacent components is investigated through observing the cross-sectional view of the test cell. Furthermore, the effectiveness of the contact layer in inhibiting Cr migration is also assessed.

The EFCF conferences in series continued with the 15^th European SOFC & SOE Forum (EFCF2022), taking place between 5–8 July 2022 in Lucerene, Switzerland.

Although an European based event, the forum has evolved to the largest international event and leading meeting place in Europe. The 2022 edition was also a special event, due to the international context, related to the European Commission's “RePowerEU” plan to save energy, produce clean energy and diversify energy supplies in the context of the war in the Ukraine.

The 15^th European SOFC & SOE Forum provided a global overview of the current SOFC & SOE technology developments in a well-balanced program covering technology development and scientific achievements, from fundamental research to the latest achievements in terms of demonstrations (https://www.efcf.com/2022).

Solid oxide electrolysis is considered an efficient technology to produce hydrogen. To deploy electrolysers at the GW scale, an increase in the individual component size (cells and stacks in particular) is required. The integration of larger cells (200 cm² active area) into 25-cell stacks has been successfully performed. Performances were in the range of –0.8 to –0.9 A cm⁻² at 1.3 V at 700°C. The number of cells has also been increased to 50 and 75 cells. For this latter 75-cell stack, the assembly of three 25-cell substacks was considered. Good gastightness and high performances were achieved, although connections between substacks add a serial resistance that affects the stack total performances. Nevertheless, a current density of more than –0.8 A cm⁻² was obtained at 1.3 V and 700°C, consistent with individual substack performances. Finally, a stack made of 50 200 cm² cells has been assembled. Although a stack deformation was visible due to individual component thickness scattering, a good gastighness was achieved and a current density of –0.9 A cm⁻² at 1.3 V and 700°C was measured. The low voltage scattering highlighted a good homogeneity of the fluidic distribution and of the electrical contacts within the stack.

Solid oxide cells (SOCs) offer the possibility to operate on hydrogen/steam (H₂/H₂O), carbon monoxide/carbon dioxide (CO/CO₂), and mixtures thereof in the fuel cell as well as in the electrolyzer mode. In this study, the electrochemical processes in an electrolyte-supported SOC exhibiting a La_w Sr_x Co_y Fe_z O_(3-δ) air electrode and a nickel/gadolinium-doped ceria (Ni/CGO) fuel electrode (FE) were analyzed by electrochemical impedance spectroscopy, and the subsequent impedance data analysis by the distribution of relaxation times for CO/CO₂ fuel mixtures. A physicochemical equivalent circuit model was fitted to the measured spectra. With the help of the extracted parameters, a zero-dimensional direct current cell model was parametrized to simulate the current-voltage behavior of the cell. This approach, previously implemented for H₂/H₂O fuel mixtures, is extended toward CO/CO₂ fuels. It will be shown that the same model – with adapted parameters for the FE – can be applied. A comparison of measured and simulated current-voltage curves showed an excellent agreement for both fuels and operating modes (solid oxide fuel cell/solid oxide electrolyzer cell). Simulations reveal that there is nearly no performance difference between H₂O and CO₂ electrolysis for the electrolyte-supported cell with Ni/CGO FE in comparison to an anode-supported cell with Ni/yttria-stabilized zirconia FE.

Background: Trigger finger (TF; a type of stenosing tenosynovitis) is common, affecting the flexor tendons of the hand, often causing significant pain and functional impairment. Treatment can include splinting, corticosteroid injection, or surgical release. There is little published research on the role of electroacupuncture (EA) for treating TF.

Case: After more than 1 year of pain and triggering, a 58 year-old male had locking of his left, fourth ring finger requiring painful manual reduction. EA was performed with 4-6 needles in a rectangular pattern along the radial and ulnar aspects of the A1 pulley of the fourth digit, with 10 Hz delivered in a daisy-chain formation for 45 minutes. Nodule size, frequency of triggering and locking, and severity of pain were assessed before and after 4 treatments over ∼1.5 months.

Results: This patient's frequency of locking and severity of pain decreased significantly by 50% after his first treatment. Additional clinically significant reductions of locking, pain, and nodule-size were evident after each treatment along with substantial functional gains between visits. After his fourth treatment, he reported 100% resolution of his symptoms with no further pain or triggering. Throughout this time, he continued his usual activities.

Conclusions: EA alone directed at the A1 pulley may be an effective treatment modality for patients with TF. The authors hypothesize that EA may reduce pain enabling a return to normal function and compression of the nodule, thus eliminating triggering. Further research evaluating the efficacy of EA for TF may help substantiate these results.

Over the past decade, the University of St Andrews and HEXIS AG have engaged in a highly successful collaborative project aiming to develop and upscale La_0.20Sr_0.25Ca_0.45TiO₃ (LSCT_A-) anode “backbone” microstructures, impregnated with Ce_0.80Gd_0.20O_1.90 (CG20) and metallic electrocatalysts, providing direct benefits in terms of performance and stability over the current state-of-the-art (SoA) Ni-based cermet solid oxide fuel cell (SOFC) anodes.

Here, we present a brief overview of previous work performed in this research project, including short-term, durability, and poison testing of small-scale (1 cm² area) SOFCs and upscaling to full-sized HEXIS SOFCs (100 cm² area) in short stacks. Subsequently, recent results from short stack testing of SOFCs containing LSCT_A- anodes with a variety of metallic catalyst components (Fe, Mn, Ni, Pd, Pt, Rh, or Ru) will be presented, indicating that only SOFCs containing the Rh catalyst provide comparable degradation rates to the SoA Ni/cerium gadolinium oxide anode, as well as tolerance to harsh overload conditions (which is not exhibited by SoA anodes). Finally, results from full system testing (60 cells within a 1.5 kW electrical power output HEXIS Leonardo FC40A micro-combined heat and power unit), will be outlined, demonstrating the robust and durable nature of these novel oxide electrodes, in addition to their potential for commercialization.

Stainless steel bipolar plates (BPs) fabricated using innovative additive manufacturing techniques can improve fuel cell performance and reduce costs. A high current density can be obtained using a low-cost membrane electrode assembly (MEA) with low platinum (Pt) loading at the anode, along with BPs with rectangular micro channels. Three types of BPs of serpentine flow field are designed after varying the width of the rectangular channel. Two types of MEAs are used. First is 0.12 mg cm⁻² Pt loading at anode, and the second is 0.50 mg cm⁻². Wherein MEA with Pt loading at 0.12 mg cm⁻² is used, a high current density is obtained as the channel width decreases. The BP with 300 µm channels has a current density of 1.205 A cm⁻², which is higher by 31.4% than that of BP with 500 µm channels and higher by 70.2% than that of the BP with 940 µm channels. However, when the MEA with Pt loading at 0.50 mg cm⁻² is applied to the test, the opposite results are obtained: As the channel width becomes narrow, the current density decreases. In the long-term operation, a similar trend in the current density as that of the short-term operation is observed.