Methanol fuel cells introduction (part 1)
Methanol fuel cell is divided into cells with direct methanol fuel (DMFC) fuel cells and re-methanol (MFRC) in two, they are mainly developed for mobile phones, laptops and other portable devices. Although the energy density of methanol fuel cells for other types of fuel cells is not high, but it is easy to carry with methanol fuel, the benefits of easy storage, which is more suitable for the methanol fuel cell portable device. Inspiron 8500 battery Inspiron 8600 battery
So far, no real products of fuel cells on the civilian market for methanol fuel cells is still underway, the search direction is concentrated in the small battery, life, energy density, efficiency energy, etc. improve the production of methanol fuel cells to really take time. After all, most people think of methanol fuel cells to replace conventional batteries as main power portable devices, you can see is the various manufacturers in recent years, launched its own prototype / prototype. This summary description of the principle of DMFC by defects leads DMFC MFRC emphasis final few prototypes and products MFRC.
1, DMFC
Regarding the technical principles, DMFC is mature. It can immediately produce a stable energy, the reaction is not necessary to cool the main battery; methanol fuel used in liquid form, because it is easy to store and do not condense in the cold environment, size and reduced weight, safety DMFC is as easy to side. All these advantages make the use of DMFC in some areas than other types of fuel cells are more advantages, such as we are lawn mowers, electric saws and other appliances DMFC devices can see the shadow You can see the passengers, shop DMFC as an energy booster, micro-DMFC portable devices become more energy alternative. Inspiron 9200 battery Inspiron B120 battery
1, DMFC reaction
DMFC usually consists of an electrolyte membrane permeable, the methanol in the DMFC anode cathode air through the DMFC. Using the chemical reaction of methanol with air to produce electricity without combustion process, and generates only CO2 and water. Methanol breaks down into hydrogen and CO2, protons, and the air is the formation of O2 H2O, while the external electronic circuit to achieve through the film negative. Chemical reaction equation is as follows:
Total reaction equation:
CH3OH +3 / 2O2 = 2H2O + CO2
Anode: CH3OH + H2O = CO2 + 6H + +-sixth
Cathode: 3/2O2 + 6H + + 3H2O = 6th-
2 defects DMFC Inspiron B130 battery Latitude D410 battery
Aqueous methanol fuel cell (DMFC) of the electrolyte membrane, most materials used perfluorooctanoic acid sulfone system, because this material formed in the internal cluster, surrounded by water molecules, protons (Proton) can form channels proton hydrates, proton conductivity is very high, but with the same combination of protons in methanol hydrate film will be reduced through the use of methanol, which is commonly called the penetration of methanol (cross) the phenomenon, once penetration of methanol with oxygen in the catalytic reaction and cathodic reduction of tension and cause other issues. Increase the capacity of the battery using the high concentration of methanol aqueous solution is very effective, but high concentrations of methanol and the methanol and water with the same ease of triggering the phenomenon requires a conductivity high proton electrolyte membrane, but also the need to control the problem of penetration of methanol. This is indeed the fatal flaw DMFC, hydrogen ions needed to complete the polymer film by water, to avoid this situation, researchers have taken a variety of other ways to prevent problems penetration of methanol, such as increased alcohol and high insulation layer insulation films using Molecular gradient hydrophobic inter alia. Latitude D800 battery Latitude D810 battery
DMFCs are facing another problem is the release of CO2. Although the supply of methanol can be used passively (ie do not use the pump), but the accumulation of CO2 in the catalyst will lead to a decline in the use of a catalyst. The use of the pump will increase the complexity and increase the size. Finally, carbon and oxygen atoms, whereas CO2 is produced with the use of CO catalyst system of platinum, CO poisoned platinum catalyst temporarily, although the electrodes can be added, such as ruthenium atoms so that was the catalyst for CO poisoning and the catalytic reaction, however, when the CO concentration is too high, causing a fuel cell electrode has been increased Ru content, which is also the DMFC, PEMFC electrode active area is 10 times the love.
3, for example DMFC
(1) Figure 3 is the Yamaha 2003 has developed a DMFC system for motorcycles. Figure 4 shows the system structure and its components for each part of the name, in Figure 5 also show the power generated by the theme of the principle and structure of the battery. The system requires an output power rating of 500W, rated voltage of 24V, and weighs 20kg. In this system includes a fuel tank and a water tank storage tank fuel level of 50% solution of methanol, the role is to ensure the supply tank of the main battery of methanol - a solution water maintained at a constant concentration of 1 M / L (3.2% mass). The main battery, the aqueous solution containing the chemical reaction of CO2 from air bubbles, the aqueous solution through a box of pipe loop transmission tub and the bubbles are isolated. Inspiron 1526 battery Inspiron 1720 battery Yamaha developed concentration sensor and control circuit specialized for monitoring the concentration of methanol, the system works is that when it reaches the battery inside the main solution to a low concentration methanol, the system will generate a control signal transmitted by a high concentration of methanol in the tank of methanol in the reaction solution to improve their concentration. In addition, Yamaha has developed its own highly efficient air pump air to the battery main body of the cathode, air pump consists of a screening program. Finally, these devices in the air after the heat exchanger of the steam room, where the use of heat to expedite the progress of the concentration of the solution, and finally they sent the system is transferred. Box in the low concentration solution, the solution used the humidity is controlled, and excess water will be discharged outside the system. To integrate the system into a motorcycle, the structure of the battery should be based on the shape of a motorcycle adapted accordingly to achieve weight balance. Inspiron 1721 battery Inspiron 2600 battery
(2) MTI developed for military DMFC. Figure 6 shows in November 2006 to demonstrate fuel cell fuel cell, see (a) shows the MTI developed for military purposes “1M Mobion” portable fuel cell, it uses a concentration of 100% methanol as fuel 0.7 watts nominal, the external dimensions of 34mm × 95mm × 153mm. box fuel for built-in way, each filled with the energy density of 150Wh. Thanks to technology Mobion MIT may be a concentration of 100% methanol directly into the anode DMFC, thereby avoiding the need for other types of DMFC methanol in water to the battery of the main problems in the system also eliminates the need for the addition of micro-pumps and micro - sub-catheter systems. Its principle can refer to Figure 7, the MTI technology to keep constant by controlling the supply of 100% concentration of methanol, and do not use the pump in the case of uniform distribution of them with the main battery. Inspiron 2650 battery Inspiron 5150 battery
Secondly, MFRC
MFRC is actually re-methanol PEMFC, also using methanol as the main raw material. The difference is to use an external reformer, which is usually miniature methanol reformer. In MFRC, methanol is not directly to the main battery of chemical reaction, which avoids the shortcomings described above in DMFC, but it can also address the lack of output power DMFC. Casio Hitachi last year and the results of research, we can see the output of methanol fuel cell energy density of 200mW / cm2 or more, it implies that it can cross 10W output power to drive portable devices. Inspiron 5160 battery Inspiron 6000 battery