Abstract Reversible protonic ceramic cells (R-PCCs) can function at lower temperatures due to the lower activation energy required for proton conduction. In this work, a series of perovskite materials BaZrxFe0.9-xNb0.1O3(x=0, 0.05, 0.1) are synthesized. Characterization results reveal that the introduction of Zr effectively reduced the average valence states of Fe and Nb in the original perovskite matrix, promoting an increase in surface oxygen vacancy concentration. Electrochemical tests on symmetrical cells show that Zr doping positively influence the oxygen reduction reaction (ORR) activity. When the Zr doping amount is 0.1, the polarization resistance (Rp) of the symmetrical cell decreases to 0.23 Ω cm2, a 72.3% reduction compared to the undoped sample. Additionally, the Rp remained stable under different humidity environments (PH2O=0.03-0.10 atm), while it exhibits an exponential decrease with increasing PO2, confirming that the ORR kinetics are limited by the oxygen exchange process at the electrode surface. In addition, a single cell with BaZr0.1Fe0.8Nb0.1O3 as the air electrode achieves a maximum power density of 755 mW cm-2 in fuel cell mode and a current density of 1037 mA cm⁻² under 1.3 V electrolysis mode at 700 °C, using wet H2 (3%H2O) as the fuel and wet air (30%H2O) as the oxida
Abstract Silicon-containing lithium-ion cells provide higher energy density than cells with only graphite in the negative electrode. This paper investigated the impact of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) on the performance of lithium-ion pouch cells with NMC-type positive electrodes (Ni83-type and Ni65-type) and 20 % chemical silicon-carbon (chemical SiC) in their negative electrode. The additive blends consisted of 2 wt. % VC with either 0, 4, or 10 wt. % FEC. Insitu volume measurements were carried out to study the impact of additives on gas volume produced during the formation step. Long-term cycling tests at 40 °C and 55 °C, and storage experiments at 60 °C, were conducted to investigate the effect of the additives on cell performance. Post-cycle analyses were conducted on cells using impedance spectroscopy (EIS) and gas chromatography-mass spectrometry (GC-MS). The results demonstrate that 2 wt % VC is an effective additive to improve cell performance in both Ni83-type and Ni65-type pouch cells with 20 % chemical SiC. The additive blend, 2 wt % with 4 wt % FEC, shows a positive impact, however, addition of 10 wt % FEC produces minimal additional impact.
Abstract Voltage models for Proton Exchange Membrane (PEM) electrolyzers calibrated under one set of operating conditions often fail when required to predict under different conditions, a task known in machine learning as Out-of-Sample (OOS) prediction. We address this problem with knowledge distillation, in which a hybrid teacher combining the electrochemical equations (Nernst equation, Butler–Volmer kinetics, Ohm's law) with a bounded neural network correction is distilled into a 12-parameter physics-based student. Using OOS datasets from a Static Water Vapour Feed (SWVF) PEM electrolyzer, we show that the student predicts voltage more accurately than conventional fitting of the same equations, with a mean absolute error (MAE) of 9.2 mV across two evaluation campaigns with different operating protocols, approximately 75% lower than Levenberg–Marquardt nonlinear least squares (37.2 mV) and 70% lower than gradient-based fitting (30.4 mV). The deployed model is a closed-form expression of 12 constants (six effective electrochemical parameters, six empirical correction constants) and runs without machine-learning software.
Abstract Electrochemical impedance spectroscopy revealed that Cu electrodes exhibited lower low-frequency resistance and lower polarization than Ni electrodes during both fluorination and defluorination reactions. The impedance response of Cu exhibited a behavior indicative of a diffusion contribution, whereas no such behavior was observed for Ni. In Cu 0.72 Ni 0.28 films, diffusion-related impedance behavior also emerged in the CuF 2 /Cu plateau region. Furthermore, compared with pure Ni films, Cu 0.72 Ni 0.28 films exhibited lower low-frequency resistance during NiF 2 defluorination, resulting in a more positive onset potential for NiF 2 defluorination than that of Ni electrodes. These results suggest two possible mechanisms: (1) F vacancies, which are known to form readily in CuF 2 , may play an important role in promoting F transport, possibly through a mixed ionic/electronic conduction mechanism, thereby enabling ambipolar diffusion in CuF 2 and suppressing the increase in overpotential; and (2) defluorinated metallic Cu may facilitate electron transfer to adjacent NiF 2 , thereby reducing the overpotential for NiF 2 defluorination. Overall, the present findings highlight the potential importance of enhancing F transport through vacancy engineering to reduce low-frequency resistance, as well as introducing electron-conduction pathways into metal fluorides to improve reaction kinetics and rate capability in all-solid-state fluoride shuttle batteries.
Micro-jet electrochemical deposition, with concentrated current, fast deposition and flexible fabrication, is widely used in metal additive manufacturing. However, its direct-current mode suffers from low efficiency, poor surface quality and inferior material performance. To overcome these limitations, high-frequency pulse power is adopted for copper electrodeposition. First, current density, electric field distribution, copper pillar growth and grain evolution are simulated under various electrical parameters. Second, Taguchi experiments identify optimal pulse parameters. Third, XRD and EBSD characterize grain structures of pulse and DC-deposited specimens comparatively. Finally, nanoindentation and electrochemical tests evaluate mechanical and anti-corrosion performances. The surface roughness of copper pillar samples printed under optimal parameters can reach 69 nm. Grains are refined from micrometer to nanometer scale with 0.203 nm atomic spacing. The optimized high-frequency-pulse copper pillar achieves a hardness of 4757.2 MPa, 1109.7 MPa higher than its DC-deposited counterpart. It has a self-corrosion potential of −0.3021 V (vs −0.4187 V for DC sample) and a corrosion current density of −1.545 A cm −2 (vs −0.8761 A cm −2 ). The results show markedly improved mechanical properties and corrosion resistance. High-frequency pulse micro-jet electrodeposition improves performances via grain refinement and is promising for electrodeposited metal structure fabrication.
