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Supercapacitors, Batteries, Fuel Cells, and Related Applications
Published in Antonio Doménech-Carbó, Electrochemistry of Porous Materials, 2021
Direct methanol fuel cells are based on the electrochemical oxidation of methanol at an anode. The main problem is the disposal of a suitable catalyst for the complete oxidation of methanol to CO2 and H2O: CH3OH+H2O→CO2+6H++6e−
Applications of Perovskite Oxides
Published in Gibin George, Sivasankara Rao Ede, Zhiping Luo, Fundamentals of Perovskite Oxides, 2020
Gibin George, Sivasankara Rao Ede, Zhiping Luo
In Direct Methanol Fuel Cells (DMFC), methanol is used as a fuel, which is oxidized electrochemically at the anode and generates electricity, and oxygen is reduced (ORR) at the cathode. The perovskites with transition metals at B-sites can be a promising non-noble metal cathode in DMFCs. Lanthanum-based perovskites with the general formula LaMO3 (M = Co, Mn, Ni, Fe) are promising candidates for ORR in alkaline medium with the characteristics of that of noble metal catalysts. The partial substitution of A-site cations with Ca and Sr enhances the current densities at a lower overpotential; however, the transitions metals at B-site plays a significant role in improving the ORR catalysis any further. The presence of two transition elements in the B-site exhibits better activity than the one with the single element at the B-site. The ORR current density of La-based perovskites is in the following order: LaCoO3 > LaMnO3 > LaNiO3 > LaFeO3 > LaCrO3. Moreover, the perovskite materials on carbon-based support materials such as graphene and CNTs are more active than the pure perovskites due to the synergic activation mechanism in the composites (Zhu et al. 2015).
Nanoparticles for Fuel Cell Applications
Published in Claudia Altavilla, Enrico Ciliberto, Inorganic Nanoparticles: Synthesis, Applications, and Perspectives, 2017
Jin Luo, Bin Fang, Bridgid N. Wanjala, Peter N. Njoki, Rameshwori Loukrakpam, Jun Yin, Derrick Mott, Stephanie Lim, Chuan-Jian Zhong
In PEMFC, electrochemical reactions occur at the surface of the catalyst at the interface between the electrolyte and the membrane. Hydrogen fed on the anode side of the membrane splits into protons and electrons. Protons travel through the membrane, while the electrons travel through the outside circuit where they perform useful work and return to the cathode side of the membrane. At the catalyst sites of the cathode oxygen is reduced, which combines with the protons, forming water. The net result of these simultaneous reactions is the current of electrons through an external circuit—direct electrical current. There are many types of fuel cells. In addition to the most popular hydrogen/air fuel cells, another type of fuel cells such as direct methanol fuel cell (DMFC) has also become attractive because of high conversion efficiency, low pollution, lightweight, high power density, and applications from small power supplies for electronic devices such as PCs, notebooks, and cellular phones.
Influence of intermediate liquid electrolyte layer on the performance of passive direct methanol fuel cell
Published in International Journal of Green Energy, 2019
Muralikrishna Boni, S. Srinivasa Rao, G. Naga Srinivasulu
Direct methanol fuel cell (DMFCs) is an interesting source of electrical energy for charging of portable electronic devices. DMFC consists of anode and cathode end plates, proton exchange membrane (PEM), flow fields on anode and cathode side. DMFC produces higher volumetric energy density compared to gases fuels. Direct methanol fuel cells can be both passive and active types (Mallick, Thombre, and Shrivastava 2016). In an active direct methanol fuel cell system, the oxidant at the cathode and fuel at the anode are supplied externally by a compressor and a pump, respectively, while in the passive DMFC system, the supply of reactants is through diffusion and natural convection at the anode and cathode, respectively. Therefore, the passive DMFC has higher mass transfer resistances compared to active DMFC. The rate of reaction in an active DMFC is higher compared to the passive DMFC. This results in higher cell temperature in an active DMFC compared to passive DMFC. However, since the mass flow rates of the reactants can be controlled in an active DMFC, the cell temperature can be regulated. On the other hand, since the reactions are fed by diffusion and natural convection in a passive DMFC, the cell temperature can not be effectively regulated. The DMFC has the advantages of low fuel cost, small operating temperature and pressure range, re-fueling, simple operation, simple structure design, and light weight compared to Proton Exchange Membrane Fuel cells (Banerjee, Kingshuk, and Rana 2019).
SPVdF-HFP/SGO nanohybrid proton exchange membrane for the applications of direct methanol fuel cells
Published in Journal of Dispersion Science and Technology, 2020
Ranganathan Hariprasad, Mohanraj Vinothkannan, Ae Rhan Kim, Dong Jin Yoo
Polymer electrolyte membranes (PEMs) are being studied extensively because of their potential application to energy storage and conversion devices such as fuel cells, batteries, super capacitors, etc.[1] Direct methanol fuel cells (DMFCs) are one of the sub categories of fuel cell, gaining extensive attention due to their high energy density, compact cell design, inexpensive liquid fuel, low operating temperature, and no fuel reforming issues.[2,3] DMFCs use PEMs for the transportation of protons from anode to cathode and also for the separation of two half-cell reactions. DMFCs use PEMs for the transportation of protons from anode to cathode and also for the separation of two half-cell reactions. Furthermore, the separating process of a PEM includes separation of two reactants. A good PEM should act as a good separator by possessing low methanol crossover because high methanol cross over will decrease the electrochemical potential of cathode and which in turn lead to a loss in overall DMFC performance.[4,5] Because of its high proton conductivity, low electrical conductivity, and better thermochemical stability, DuPont’s Nafion is being studied widely as PEM for DMFC applications.[6] However, the Nafion has some unsolved demerits such as high methanol crossover, low proton conductivity (above 80 °C), and high cost.[6–8] Hence, the fabrication of alternative PEMs for DMFCs has gained great attention among the researchers.
Effect of air supply on the performance of an active direct methanol fuel cell (DMFC) fed with neat methanol
Published in International Journal of Green Energy, 2018
Qian Xu, Weiqi Zhang, Jian Zhao, Lei Xing, Qiang Ma, Li Xu, Huaneng Su
A direct methanol fuel cell (DMFC) is an electrochemical energy conversion device that directly converts the chemical energy stored in methanol into electricity. The market opportunity for DMFCs as portable power source of mobile electronic devices is promising as compared with conventional batteries, because DMFCs have several distinct advantages, e.g. system simplicity, easy refueling, and high energy density (Dillon, Srinivasan, and Arico 2004; Kamarudin, Daud, and Ho 2007; Munjewar, Thombre, and Mallick 2017). Nevertheless, the overall cell performance has not reached to the expected level although great efforts have been involved during past decades. The main technological issues are: sluggish and complicate kinetics of the methanol oxidation reaction (MOR) (Liu et al. 2006; Sun, Xing, and Scott 2010; Wang 2004; Xing et al. 2016) and the permeation of methanol from the anode through electrolyte membrane to the cathode, which is called ‘methanol crossover (MCO)’ (Heinzel and Barragan 1999; Shironita et al. 2014). MCO not only causes a mixed potential at cathode, but also leads to a waste of fuel, lowering the overall efficiency of fuel cells (Li and Faghri 2013). The MCO rate is associated with the methanol concentration in anode catalyst layer (ACL). The conventional way to alleviate the impact of MCO is to feed a diluted methanol solution (i.e. 1–2 M for active fuel supply systems and 3–5 M for passive DMFC) to the anode (Bae et al. 2006; Chan et al. 2008; Liu et al. 2005; Mallick, Thombre, and Shrivastava 2016). However, this method would also cause a large decrease in system specific energy, hence loses the most attractive feature of DMFC–high energy density.