High power portable electronic devices

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... 

In an acidic medium, a PEMFC fed with ethanol allows power densities up to 60 mW cm to be reached at high temperatures (80-120 °C), but this needs platinum-based catalysts, which may prevent wider applications for portable electronic devices. On the other hand, in an alkaline medium, the activity of non-noble catalysts for ethanol or ethylene glycol oxidation and oxygen reduction is sufficient to reach power densities of the order of 20 mW cm at room temperature. This opens up the hope of developing SAMFCs that are particularly efficient for large-scale portable applications. 

It should also be noted that the demand for primary lithium batteries remains strong, particularly in military applications where there is high demand for lightweight and disposable power supplies for portable electronic devices. In fact, the US General Accounting Office (GAO) has indicated that primary lithium batteries were one of seven items for which supply shortages reduced operational capability and increased risk to [US] troops [3]. 

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). 

Most portable electronic devices would require a fuel cell of less than 100 W output, and often considerably less. Here, effort is concentrated on perfecting the DMFC, because of the convenience of methanol as a liquid fuel. Clearly, portable power is a very promising high-value opportunity for small fuel cells, but the outcome would have little impact on overall energy consumption and is not strictly part of the hydrogen energy scene. Nevertheless, many observers believe that volume production of micro fuel cells would be a key technical and economic driver for the entire fuel-cell market. 

Hence, EDLCs have attracted considerable interest, given the ever increasing demands of electric vehicles, portable electronic devices, and power soirrces for memory backup. The capacitance of an EDLC depends on the surface area of the electrode materials. Therefore, activated carbons are necessary materials for EDLC electrodes because of their large surface area, highly porous structure, good adsorption properties, and high electrical conductivity. The electrochemical performance of EDLCs is related to the surface area, the pore structure, and the surface chemistry of the porous carbon. 

The tremendous growth in high-power-demand portable electronic devices in the last decade has increased the demand for lightweight, readily recharged batteries. One of the most common rechargeable batteries is the nickel-cadmium (nicad) battery. During discharge, cadmium metal is oxidized at the anode while nickel oxyhydroxide [NiO(OH)(s)] is reduced at the cathode ... 

The present sealed Ni-Cd sinter plate battery technology evolved from the sealed battery technology developed by Varta in the 1940 s based on an IG Farben development in the 1930 s. The sinter plate construction, developed in the 1940 time frame, has low internal resistance, superior high rate and low temperature performance compared to the pocket plate cell design. The batteries are sealed and can be used in any orientation. This battery powered the Luftwaffe in the 1940s, the early flights in the space program and in the development of portable electronic devices, such as cellular phones and portable notebook computers. 

Artificial sources of radiation are commonly used in industry, research, medicine, nuclear power plants (NPP), etc. Some workers are exposed to natural sources, for example, in mines and other conditions where the radon concentration in air might be higher than in normal cases. Relatively high dose rates are measured during air travel due to the elevated levels of cosmic rays at high altitudes. This means that many people are exposed in their work. Some of them are monitored individually, for example, by a small photographic film, thermoluminescent material, or portable electronic devices. These types of detectors on the body register the dose due to the external sources and yield an estimate of the dose received by the wearer. 

---