Optimizing the Anode Structure of a Passive Tubular-Shaped Direct Methanol Fuel Cell to Operate With High Concentration Methanol

2012 ◽  
Vol 9 (5) ◽  
Author(s):  
Jing Huang ◽  
Travis Ward ◽  
Amir Faghri
Keyword(s):  
Energy Density ◽  
Low Power ◽  
Power Density ◽  
Direct Methanol Fuel Cells ◽  
Fuel Efficiency ◽  
High Energy ◽  
Energy Output ◽  
Methanol Crossover ◽  
High Concentration ◽  
Direct Methanol

In order to take full advantage of the high energy density available in methanol fuel, one must use high concentration methanol in direct methanol fuel cells (DMFCs). However, this causes severe methanol crossover and leads to low power density and fuel efficiency. In this work, a tubular shape is adopted to generate higher volumetric power density; porous polytetrafluoroethylen (PTFE) membranes at the anode are used to control methanol transport with a high concentration fuel. A novel passive tubular-shaped DMFC is improved to achieve stable operation with methanol concentrations up to 20 M. It is observed that a balance between fuel transport resistance, power density, energy density, and fuel efficiency exists. Increased resistance enhances fuel efficiency, hence, energy density, but limits the fuel supply and causes low power density. With the improved anode structure and higher concentration fuel (1 M to 15 M), the energy output of the tubular DMFC increases 591%, from 0.094 Wh to 0.65 Wh with 2 ml fuel. The power densitymaintains the same level as 16 mW/cm2. For different fuel concentrations, there exists an optimum structure to generate the highest power density, which is a result of minimizing the methanol crossover while also providing sufficient fuel. The discharge characteristic at constant voltage and its effect on fuel efficiency are also discussed.

Steady and Pulsed Flow Performance Trends of Higher Concentration DMFCs

2006 ◽  
Author(s):  
Larry McCarthy ◽  
Comas Haynes
Keyword(s):  
Energy Density ◽  
Direct Methanol Fuel Cells ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Methanol Crossover ◽  
Fuel Delivery ◽  
Fuel Mixtures ◽  
The Impact ◽  
Promising Source

Direct methanol fuel cells (DMFCs) are a promising source of energy due to their potentially high energy density, facilitated fuel delivery and storage, and precluded fuel processing. However, DMFCs have several challenges which need to be resolved before they can replace existing energy sources. Some of these challenges include lower power density, relatively high cost, and uncertain reliability. These issues are all promoted, at least in part, by the methanol crossover phenomenon, wherein membrane permeability allows the undesirable species transport of methanol from the anode to the cathode. This phenomenon also causes the requirement of dilute fuel mixtures, which is undesirable from an energy density viewpoint. Prior research has shown that methanol crossover can be reduced by operating DMFCs in a transient mode [1,2]. Thus, a study has been performed to investigate the impact of hydraulic pulsing (HP) at different operating conditions, such as fuel concentration, current density, and number-of-stoichs (NOS). Furthermore, the cell’s performance is being characterized at different steady flow concentrations to highlight the impact of fuel dilution.

scholarly journals Na0.76V6O15/Activated Carbon Hybrid Cathode for High-Performance Lithium-Ion Capacitors

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 122
Author(s):  
Renwei Lu ◽  
Xiaolong Ren ◽  
Chong Wang ◽  
Changzhen Zhan ◽  
Ding Nan ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Energy Density ◽  
Power Density ◽  
Cathode Materials ◽  
Low Cost ◽  
Lithium Ion ◽  
High Energy ◽  
Cycling Stability ◽  
High Energy Density ◽  
Artificial Graphite

Lithium-ion hybrid capacitors (LICs) are regarded as one of the most promising next generation energy storage devices. Commercial activated carbon materials with low cost and excellent cycling stability are widely used as cathode materials for LICs, however, their low energy density remains a significant challenge for the practical applications of LICs. Herein, Na0.76V6O15 nanobelts (NaVO) were prepared and combined with commercial activated carbon YP50D to form hybrid cathode materials. Credit to the synergism of its capacitive effect and diffusion-controlled faradaic effect, NaVO/C hybrid cathode displays both superior cyclability and enhanced capacity. LICs were assembled with the as-prepared NaVO/C hybrid cathode and artificial graphite anode which was pre-lithiated. Furthermore, 10-NaVO/C//AG LIC delivers a high energy density of 118.9 Wh kg−1 at a power density of 220.6 W kg−1 and retains 43.7 Wh kg−1 even at a high power density of 21,793.0 W kg−1. The LIC can also maintain long-term cycling stability with capacitance retention of approximately 70% after 5000 cycles at 1 A g−1. Accordingly, hybrid cathodes composed of commercial activated carbon and a small amount of high energy battery-type materials are expected to be a candidate for low-cost advanced LICs with both high energy density and power density.

scholarly journals Novel Lithium-Ion Capacitor Based on a NiO-rGO Composite

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3586
Author(s):  
Qi An ◽  
Xingru Zhao ◽  
Shuangfu Suo ◽  
Yuzhu Bai
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Power Density ◽  
High Power ◽  
Specific Capacity ◽  
Lithium Ion ◽  
High Energy ◽  
Cycle Life ◽  
High Energy Density ◽  
Lithium Ion Capacitor

Lithium-ion capacitors (LICs) have been widely explored for energy storage. Nevertheless, achieving good energy density, satisfactory power density, and stable cycle life is still challenging. For this study, we fabricated a novel LIC with a NiO-rGO composite as a negative material and commercial activated carbon (AC) as a positive material for energy storage. The NiO-rGO//AC system utilizes NiO nanoparticles uniformly distributed in rGO to achieve a high specific capacity (with a current density of 0.5 A g−1 and a charge capacity of 945.8 mA h g−1) and uses AC to provide a large specific surface area and adjustable pore structure, thereby achieving excellent electrochemical performance. In detail, the NiO-rGO//AC system (with a mass ratio of 1:3) can achieve a high energy density (98.15 W h kg−1), a high power density (10.94 kW kg−1), and a long cycle life (with 72.1% capacity retention after 10,000 cycles). This study outlines a new option for the manufacture of LIC devices that feature both high energy and high power densities.

Flexible high-energy asymmetric supercapacitors based on MnO@C composite nanosheet electrodes

2017 ◽  
Vol 5 (2) ◽  
pp. 804-813 ◽  
Author(s):  
Neng Yu ◽  
Kai Guo ◽  
Wei Zhang ◽  
Xianfu Wang ◽  
Ming-Qiang Zhu
Keyword(s):  
Energy Density ◽  
Power Density ◽  
High Energy ◽  
Asymmetric Supercapacitor ◽  
Asymmetric Supercapacitors ◽  
Positive Electrodes

A flexible asymmetric supercapacitor assembled with novel MnO@C composite nanosheets and Co3O4 nanosheets as negative and positive electrodes achieves an exceptional energy density of 59.6 W h kg−1 at a power density of 1529.8 W kg−1.

scholarly journals Advanced Nonflammable Localized High‐Concentration Electrolyte for High Energy Density Lithium Battery

2021 ◽  
Author(s):  
Mengmin Jia ◽  
Chi Zhang ◽  
Yawei Guo ◽  
Linshan Peng ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Energy Density ◽  
Lithium Battery ◽  
High Energy ◽  
High Energy Density ◽  
High Concentration

Sulfonated polyether ether ketone/strontium zirconite@TiO2 nanocomposite membranes for direct methanol fuel cells

2017 ◽  
Vol 5 (38) ◽  
pp. 20497-20504 ◽  
Author(s):  
G. Gnana kumar ◽  
Arumugam Manthiram
Keyword(s):  
Fuel Cells ◽  
Power Density ◽  
Direct Methanol Fuel Cells ◽  
Inorganic Filler ◽  
Nanocomposite Membranes ◽  
Polyether Ether Ketone ◽  
Sulfonated Polyether Ether Ketone ◽  
Direct Methanol ◽  
Ether Ketone ◽  
Methanol Fuel Cells

The use of SrZrO3@TiO2 nanocuboids as an inorganic filler in SPEEK membranes enhances their performance in DMFCs with a power density higher than that achieved with a Nafion 117 membrane.

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