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Effect of Geometry Variation in a Polymer Electrolyte Membrane Fuel Cell

Siemens Digital Industries Software-Carlo Locci, Chris Lueth, Huong Nguyen, Karin Frojd
  • Technical Paper
  • 2020-01-1174
To be published on 2020-04-14 by SAE International in United States
Water transport at high current densities is of main concern for polymer electrolyte membrane (PEM) fuel cells. The water content of the membrane must be high enough to provide maximum electrical conductivity and thus optimal stack performance. Dry-out may also lead to membrane degradation. However, a too high level of humidity leads to cell flooding, blocking the air and fuel flows to the catalyst sites and thus the reactions, resulting in a drop-in efficiency. Fuel cells water transport physics requires further investigation due to its complexity [1,2] and numerical modelling can improve the fundamental understanding of the phenomena. In this work, a 3D comprehensive model for fuel cells is presented. The PEM fuel cell is modelled in Siemens Simcenter STAR-CCM+ [3]. Anode and cathode GDL are modelled as porous media, with electrochemical reactions calculated in an infinitely thin catalyst layer. The membrane is modelled as a solid block including proton and water transport with electro-osmotic drag as well as ohmic heating. A two-phase approach is used to model the gas mixture and liquid water transport…
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Investigation of the operating conditions on the water and thermal management for a polymer electrolyte membrane fuel cell by one-dimensional model

Tongji Universtiy-Xuhui Wang, Yaqian Dong, Sichuan Xu
  • Technical Paper
  • 2020-01-0856
To be published on 2020-04-14 by SAE International in United States
Water and thermal management is an essential issue that influences performance and durability of a polymer electrolyte membrane fuel cell (PEMFC). Water content in membrane decides its ionic conductivity and membrane swelling favors the ionic conductivity, resulting in decreases in the membrane’s ohmic resistance and improvement in the output voltage. However, if excessive liquid water can’t be removed out of cell quickly, it will fill in the pores of catalyst layer (CL) and gas diffusion layer (GDL) then flooding may occur. It is essential to keep the water content in membrane at a proper level. In this work, a transient isothermal one-dimensional model is developed to investigate effects of the relative humidity of inlet gas and cell temperature on performance of a PEMFC. Comprehensive physical and chemical phenomenon inside the cell is included, especially the mass transfer of hydrogen, oxygen, vapor and liquid water in gas channels, GDL and CL and non-frozen membrane water in ionomer. Phase change between vapor and liquid water is also considered. The cell’s performances at the conditions of the different…
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Methods for Leak Testing Lithium-Ion Batteries to Assure Quality with Proposed Rejection Limit Standards

Inficon GmbH-Daniel Wetzig, Maximillian Reismann
  • Technical Paper
  • 2020-01-0448
To be published on 2020-04-14 by SAE International in United States
A method is presented discussing how to reliably and quantitatively detect leakage from battery cells through the detection of escaping liquid electrolyte vapors, typically dimethyl carbonate (DMC). The proposed method does not require the introduction of an additional test gas into battery cells. The test system, which is non-destructive in nature, is applicable to non-rigid pouch cells and rigid prismatic or cylindrical cells.Lithium-ion batteries are a more suitable energy source for many applications because of their high energy density and low self-discharge rate. In the automotive powertrain sector, the lithium-ion battery market share is growing rapidly, with particularly high demand being placed on battery service life and safety. Requirements regarding maximum cell temperature, electrical load power or discharge power of the cell can be controlled by cooling and power management of the battery cell. A single defect in a cell housing can only be detected through leak detection of each battery cell. The lifetime of a battery strongly depends on the tightness of the cell housing, because of the harmful effects caused by the interaction…
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‘Laxatives’ may ease challenge of lithium-ion alternative

Automotive Engineering: January/February 2020

Stuart Birch
  • Magazine Article
  • 20AUTP02_10
Published 2020-01-01 by SAE International in United States

The R&D dimension of the automotive industry often reveals novel solutions and cross-linking between materials, but a team of international scientists has come up with something truly unusual: boosting supercapacitor power and efficiency using newly developed “laxatives.” It's all about developing improved electrolytes as part of a program to enhance supercapacitor performance, making them more practical with enhanced energy storage for use in hybrid and electric vehicles (EVs).

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Chemical Mixture Widens the Temperature Range for Electric Car Batteries

  • Magazine Article
  • TBMG-35708
Published 2019-12-01 by Tech Briefs Media Group in United States

A combination of chemicals was created that could help electric cars power their way through the extreme temperatures that degrade the efficiency of current lithium-ion batteries. Combinations of compounds in electrolytes, in the laboratory, allow lithium-ion batteries to function very well both in sub-zero temperatures (Fahrenheit) — which are reached often during the winter in the northern United States and other parts of the world — and in very hot temperatures like those in the summer in the southwestern US. Those are temperatures where today's batteries — used to power electric cars, cellphones, laptops, and other devices — often retain little charge and expend it quickly.

Products of Tomorrow: September 2019

  • Magazine Article
  • TBMG-35123
Published 2019-09-01 by Tech Briefs Media Group in United States

Microneedles Extract Fluid for Wearable Sensors

  • Magazine Article
  • TBMG-34916
Published 2019-08-01 by Tech Briefs Media Group in United States

Interstitial fluid is clear, colorless, and similar to blood plasma. Continual sampling of important biomarkers in interstitial fluid could help monitor and diagnose many diseases and disorders. These markers include electrolytes — salts such as potassium and sodium that get out of balance during dehydration; glucose, a sugar that diabetics need to monitor constantly; and lactate, a potential marker of physical exhaustion or life-threatening sepsis.

Hybrid Cathodes Could Boost Energy Capacity of Lithium Batteries

  • Magazine Article
  • TBMG-34926
Published 2019-08-01 by Tech Briefs Media Group in United States

Today's lithium-ion batteries use cathodes (one of the two electrodes in a battery) made of a transition metal oxide. Batteries with cathodes made of sulfur are considered a promising alternative to reduce weight. Designers of lithium-sulfur batteries face a tradeoff. The cathodes of such batteries are usually made in one of two ways: intercalation or conversion. Intercalation types — which use compounds such as lithium cobalt oxide — provide a high volumetric energy density, packing a lot of punch per volume because of their high densities. These cathodes can maintain their structure and dimensions while incorporating lithium atoms into their crystalline structure.

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Mechanical Behavior of Representative Volume Element Specimens of Lithium-Ion Battery Modules without and with Electrolyte under Quasi-Static and Dynamic In-Plane Compressive Loading Conditions

SAE International Journal of Materials and Manufacturing

University of Michigan, USA-Eui Seop Kim, Shin-Jang Sung, Jwo Pan
University of Ulsan, Republic of Korea-Sung-Tae Hong
  • Journal Article
  • 05-12-03-0014
Published 2019-07-02 by SAE International in United States
Small rectangular representative volume element (RVE) specimens of lithium-ion battery modules without and with electrolyte were tested under quasi-static and dynamic in-plane constrained compressive loading conditions. Effects of electrolyte and loading rate on the compressive behavior of RVE specimens were examined. The test results show that the average buckling stress of the specimens with electrolyte is higher than that of the specimens without electrolyte under both quasi-static and dynamic loading conditions. The test results also show that the average buckling stress of the specimens under dynamic loading conditions is higher than that of the specimens under quasi-static loading conditions, without or with the presence of electrolyte in the specimens. The percentage of increase of the average buckling stress of the specimens due to electrolyte under dynamic loading conditions is more than that of the specimens under quasi-static loading conditions. The percentage of increase of the average buckling stress for the specimens with electrolyte from the quasi-static to dynamic loading conditions is more than that for the specimens without electrolyte.
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Toyota's proven fuel-cell stack reduces cost, complexity in H2 semi-truck

SAE Truck & Off-Highway Engineering: June 2019

Sebastian Blanco
  • Magazine Article
  • 19TOFHP06_14
Published 2019-06-01 by SAE International in United States

Hydrogen proponents likely know that Mirai means “future” in Japanese, but Toyota is only just beginning to explore how important the fuel cell stack in its H2-powered passenger car will be to the future of the company.

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