Power source for portables

The authors developed a multi-layered microreactor system with a methanol reforma- to supply hydrogen for a small proton exchange membrane fiiel cell (PEMFC) to be used as a power source for portable electronic devices [6]. The microreactor consists of four units (a methanol reformer with catalytic combustor, a carbon monoxide remover, and two vaporizers), and was designed using thermal simulations to establish the rppropriate temperature distribution for each reaction, as shown in Fig. 3. 

In recent decades, direct alcohol fuel cells (DAFCs) have been extensively studied and considered as possible power sources for portable electronic devices and vehicles in the near future. The application of methanol is limited due to its high volatility and toxicity, although it is relatively easily oxidized to CO2 and protons. So other short chain organic chemicals especially ethanol, ethylene glycol, propanol, and dimethyl... 

Since its introduction in 1990, the secondary rechargeable lithium-ion battery (LIB) with high energy density and power capability has become an important power source for portable electronic devices, such as cellular phones, laptop computers, and portable media players. Recently, LIB research has also widened to include the hybrid electric vehicles (HEV). 

S. Gottesfeld, M. S. Wilson, Polymer electrolyte fuel cells as potential power sources for portable electronic devices, in New Trends in Electrochemical Technology En-ergy Storage Systems in Electronics (Eds. ... 

Direct methanol fuel cells (DMFCs) are potentially compact, high efficiency power sources for portable applications. One of the major problems of DMFCs is methanol crossover, meaning that methanol molecules can permeate through the Nafion membrane... 

Recently, there has been a growing interest in miniaturizing DMFCs and exploring their potential as a long-life and charge-free power source for portable and mobile... 

Thulium metal is soft, ductile, and malleable and can be cut with a knife. It tarnishes when in contact with air and reacts with water. Thuhum has very few commercial uses. Radioactive thulium can be utihzed as a power source for portable x-ray machines and is produced by irradiating the element in a nuclear reactor. Thulium may also be utihzed to make magnetic ceramic materials found in microwave equipment, see also Cleve, Per Theodore. 

Carbon aerogels and xerogels have been used as supports for Pt and Pt-based electrocatalysts for proton-exchange membrane fuel cells (PEMFCs), also known as polymer-electrolyte fuel cells [56,58,83-90], These fuel cells are convenient and environmentally acceptable power sources for portable and stationary devices and electric vehicle applications [91], These PEMFC systems can use H2 or methanol as fuel. This last type of fuel cell is sometimes called a DMFC (direct methanol fuel cell). 

Scrosati, B., Power sources for portable electronics and hybrid cars Lithium batteries and fuel cells. Chemical Record, 2005, 5(5) pp, 286-297... 

While the development of primary cells with a lithium anode has been crowned by relatively fast success and such cells have filled their secure rank as power sources for portable devices for public and special purposes, the history of development of lithium rechargeable batteries was full of drama. Generally, the chemistry of secondary batteries in aprotic electrolytes is very close to the chemistry of primary ones. The same processes occur under discharge in both types of batteries anodic dissolution of lithium on the negative electrode and cathodic lithium insertion into the crystalline lattice of the positive electrode material. Electrode processes must occur in the reverse direction under charge of the secondary battery with a negative electrode of metallic lithium. Already at the end of the 1970s, positive electrode materials were found, on which cathodic insertion and anodic extraction of lithium occur practically reversibly. Examples of such compounds are titanium and molybdenum disulfides. 

More perfect power sources for portables are, to the contrary, strictly in the interest of individual manufacturers and consumers. In the past, development activities in this area were mainly market-driven and did not benefit from any general programs involving government, with the important exception, however, of work toward power sources satisfying the needs of portable equipment for the military. 

From the second half of twentieth century, acidic (proton exchange) Polymer Electrolyte Membrane Fuel Cells (PEMFC) have attracted much attention due to their potential as a clean power source for portable applications (alcohol feed). 

Table 9.2 DMFC power sources for portable applications... 

The scientific challenge of these enzymatic biofuel cells is to develop devices with compatible power and size to use them as power sources for portable devices such as GPS, mobile phone, MP3 players, or mobile computers. A steady increasing interest within enzymatic biofuel cell design is dedicated to the production of electrical energy from the electro-enzymatic degradation of glucose and O2. These... 

Abstract Direct formic acid fuel cells offer an alternative power source for portable power devices. They are currently limited by unsustainable anode catalyst activity, due to accumulation of reaction intermediate surface poisons. Advanced electrocatalysts are sought to exclusively promote the direct dehydrogenation pathway. Combination and structure of bimetallic catalysts have been found to enhance the direct pathway by either an electronic or steric mechanism that promotes formic acid adsorption to the catalyst surface in the CH-down orientation. Catalyst supports have been shown to favorably impact activity through either enhanced dispersion, electronic, or atomic structure effects. 

Ni-Cd, a typical small-sized secondary battery, however, has several drawbacks as power source for portable devices, e.g. low energy density and environmental issues. A significant improvement was made in the Ni-Cd performance, but its energy density reached a limit by the end of the 1980s. 

It has been widely said that the drain capability and low temperature performances of LPBs compare unfavorably with T.TRs due to the poor ionic conductivity of GPEs and that they cannot have sufficient performance as power sources for portable electronic equipment. 

The fuel cell is a strong contender as a power source for portable applications. Currently, the power source for portable applications is various batteries, such as Li-ion batteries, Ni-metal hydride batteries, Ni-Cd batteries, Zn-air batteries, and even Pb-acid batteries. Batteries are convenient to use, especially for low power loads (e.g., a few watts or less), but the time they can power the load is often quite short, and recharging of secondary batteries takes a few hours. A fuel cell has the potential to provide longer running time and with minimal refueling time. 

Scrosati B (2005) Power Sources for Portable Elecbonics and Hybrid Cars Lithium Batteries and Fuel Cells. Chem Rec 5 286-297. doi 10.1002/ tcr.20054- Review article on fuel cell and lithium-ion batteries for non-sta-tionary applications. 

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