A three-dimensional multicomponent multiphase lattice Boltzmann model (LBM) is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells. The gas diffusion layer (GDL) and microporous layer (MPL) are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved, and the catalyst layer is simplified as a superthin layer to address the electrochemical reaction, which provides a clear description of the flooding effect on mass transport and performance. Different kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and performance under the flooding condition. The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under flooding. The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores. Moreover, the MPL helps in the uniform distribution of oxygen for an efficient in-plane transport capacity. Crack and perforation structures can accelerate the water transport in the assembly. The systematic perforation design yields the best performance under flooding by separating the transport of liquid water and oxygen.

Thermal management in solid oxide fuel cells (SOFC) is a critical issue due to non-uniform electrochemical reactions and convective flows within the cells. Therefore, a 2D mathematical model is established herein to investigate the thermal responses of a tubular methanol-fueled SOFC. Results show that unlike the low-temperature condition of 873 K, where the peak temperature gradient occurs at the cell center, it appears near the fuel inlet at 1073 K because of the rapid temperature rise induced by the elevated current density. Despite the large heat convection capacity, excessive air could not effectively eliminate the harmful temperature gradient caused by the large current density. Thus, optimal control of the current density by properly selecting the operating potential could generate a local thermal neutral state. Interestingly, the maximum axial temperature gradient could be reduced by about 18% at 973 K and 20% at 1073 K when the air with a 5 K higher temperature is supplied. Additionally, despite the higher electrochemical performance observed, the cell with a counter-flow arrangement featured by a larger hot area and higher maximum temperature gradients is not preferable for a ceramic SOFC system considering thermal durability. Overall, this study could provide insightful thermal information for the operating condition selection, structure design, and stability assessment of realistic SOFCs combined with their internal reforming process.

Computational models that ensure accurate and fast responses to the variations in operating conditions, such as the cell temperature and relative humidity (RH), are essential monitoring tools for the real-time control of proton exchange membrane (PEM) fuel cells. To this end, fast cell-area-averaged numerical simulations are developed and verified against the present experiments under various RH levels. The present simulations and measurements are found to agree well based on the cell voltage (polarization curve) and power density under variable RH conditions (RH = 40%, RH = 70%, and RH = 100%), which verifies the model accuracy in predicting PEM fuel cell performance. In addition, computationally feasible reduced-order models are found to deliver a fast output dataset to evaluate the charge/heat/mass transfer phenomena as well as water production and two-phase flow transport. Such fast and accurate evaluations of the overall fuel cell operation can be used to inform the real-time control systems that allow for the improved optimization of PEM fuel cell performance.

A sol–gel tandem with a solid-phase modification procedure was developed to synthesize Li₂TiO₃-doped LiCoO₂ together with phosphate coatings (denoted as LCO-Ti/P), which possesses excellent high-voltage performance in the range of 3.0–4.6 V. The characterizations of X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy illustrated that the modified sample LCO-Ti/P had the dopant of monoclinic Li₂TiO₃ and amorphous Li₃PO₄ coating layers. LCO-Ti/P has an initial discharge capacity of 211.6 mAh/g at 0.1 C and a retention of 85.7% after 100 cycles at 1 C and 25 ± 1 °C between 3.0 and 4.6 V. Nyquist plots reflect that the charge transfer resistance of LCO-Ti/P after 100 cycles at 1 C is much lower than that of the spent LCO, which benefits Li-ion diffusion. Density functional theory calculations disclose the superior lattice-matching property of major crystal planes for Li₂TiO₃ and LiCoO₂, the lower energy barriers for Li-ion diffusion in Li₂TiO₃, and the suppressed oxygen release performance resulting from phosphate adsorption. This work provides useful guidance on the rational design of the high-voltage performance of modified LiCoO₂ materials in terms of lattice-matching properties aside from the phosphate coating to reduce the energy barriers of Li-ion diffusion and enhance cycling stability.

Tin (Sn)-based perovskite solar cells (PSCs) have received increasing attention in the domain of photovoltaics due to their environmentally friendly nature. In this paper, numerical modeling and simulation of hole transport material (HTM)-free PSC based on methyl ammonium tin triiodide (CH₃NH₃SnI₃) was performed using a one-dimensional solar cell capacitance simulator (SCAPS-1D) software. The effect of perovskite thickness, interface defect density, temperature, and electron transport material (ETM) on the photovoltaic performance of the device was explored. Prior to optimization, the device demonstrated a power conversion efficiency (PCE) of 8.35%, fill factor (FF) of 51.93%, short-circuit current density (J _sc) of 26.36 mA/cm², and open circuit voltage (V _oc) of 0.610 V. Changing the above parameters individually while keeping others constant, the obtained optimal absorber thickness was 1.0 μm, the interface defect density was 10¹⁰ cm^–2, the temperature was 290 K, and the TiO₂ thickness was 0.01 μm. On simulating with the optimized data, the final device gave a PCE of 11.03%, FF of 50.78%, J _sc of 29.93 mA/cm², and V _oc of 0.726 V. Comparing the optimized and unoptimized metric parameters, an improvement of ~ 32.10% in PCE, ~ 13.41% in J _sc, and ~ 19.02% in V _oc were obtained. Therefore, the results of this study are encouraging and can pave the path for developing highly efficient PSCs that are cost-effective, eco-friendly, and comparable to state-of-the-art.