batterydata/paper-abstracts huggingface dataset:
An air-breathing polymer electrolyte membrane fuel cell bears many advantages, which are important for portable-power applications. However, several barriers must be overcome before an air-breathing PEMFC achieve commercially wide-scale adoption. In this paper, with emphasis on improving the performance of air-breathing PEMFC, the simulation and experiment has been done simultaneously. Considering the natural convection in the cathode side, electrochemical reaction in the catalyst layer, water transport in the membrane, a coupled three-dimensional complex model has been developed in this work. The parameters which greatly affect the performance of an air-breathing PEMFC have been calculated for the base case such as the distribution of water and reactant, temperature and electrochemical performance. To validate the numerical result, the experiment test system have been designed to investigate the temperature distribution and cell performance. The results from this work show that the performance of air-breathing PEMFCs is strongly affected by natural convection feature. The concentration losses play a major role on the cell performance. The ambient relative humidity also has significant effect on the cell performance. The fields of water, temperature, velocity and electrochemical reaction have strong interaction on each others.
A fuel cell stack needs to be stable and high-performing for optimum commercial viability. A program was undertaken to evaluate stability of a number of proton exchange membrane (PEM) fuel cell stacks and systems by operating them as independent power units at the rated maximum power outputs. Eight convection/forced-convection stacks and systems ranging in power outputs from 3W to 150W were evaluated for periods ranging from 170h to 700h. One 300W forced-flow stack was evaluated for an 8-h period. All stacks and systems were operated self-humidified. The flow of hydrogen was kept dead-ended with periodic release to maximize its utilization. In general, the stability was observed to be excellent except of the smallest convection stack, which showed some variations from point to point. The documented stability behaviors indicate that stack and system designs were appropriate, the level of self-humidification was adequate, and that the tested products are ready for commercialization.
While the implications of information and communication technologies (ICTs) for daily travel and activities have been studied extensively, there is only scant attention paid to the relations between ICTs and space-time constraints. This study therefore explores the extent to which the Internet and mobile phone increase the spatial and temporal flexibility of everyday activities through a review of the literature and empirical research with data from Columbus (Ohio, USA) and Utrecht (The Netherlands). The analysis suggests that the implications of the Internet and mobile phone are complex and dependent on the type of activity, persons involved, technologies and socio-physical context in which they are embedded. Various regularities can, however, be detected. For the study participants, the Internet and mobile phone relax temporal constraints to a stronger degree than they enhance spatial flexibility. There are also space-time constraints that seem to persist or have come about because of ICT adoption. Finally, it appears that the Internet and mobile phone at best consolidate differences between men and women in the space-time constraints associated with everyday activities.
The cycling performance of LiPF4(C2O4) electrolyte is compared with LiPF6 electrolyte in the presence of several different electrode materials. The cycling of MCMB/LiNi1/3Co1/3Mn1/3O2 and natural graphite/LiFePO4 cells provides very similar performance for both electrolytes. However, MCMB/LiMn2O4 cells have a lower initial reversible capacity with LiPF4(C2O4) electrolytes. A detailed analysis of the surface films on both the cathode and the anode via X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) was conducted. The performance differences are attributed to the anode as opposed to the cathode.
In this work, a Sn nanoparticle (NP)/carbon nanofiber (CNF) hybrid with unique structure has been designed and fabricated via electrospinning and subsequent heat treatment. The cell assembled by the binder-free Sn NP/CNF hybrid demonstrates an effective capacity (46mAhg−1 at 200mAg−1 after 200 cycles) with high coulombic efficiency (up to 99.8%), suggesting a facile strategy for the scalable fabrication of electrochemically stable electrodes for LIBs. For understanding the electrochemical behaviors of the metallic Sn and carbon nanofibers in the lithiation/delithiation process, in situ transmission electron microscopy was applied to study the single hybrid structure. In the first charge/discharge process, real-time size variation of the Sn NP and CNFs was mainly focused, suggesting a two-step lithiation process in the metallic Sn NP. Structural characterization also indicates an irreversible delithiation in a single Sn NP/CNF hybrid structure. The electrochemical performance based on influence of carbonization temperature has also been discussed. The results and fundamental understanding of the lithiation/delithiation in the Sn-based hybrid anodes enables the communities to design flexible high-performance electrodes based on metallic active materials in a rational way.