Micro direct methanol fuel cell research
With the rapid development of industrial electronics, communications equipment and wireless products for various types of portable consumer electronics continue to emerge, and rapid growth, demand for VGP-BPS2A VGP-BPS9A batteries is also increasing, while the configuration of the battery performance put forward higher requirements. At present, widely used nickel-cadmium, nickel hydrogen and lithium-ion batteries because of their technology based manufacturing maturity, performance, development of space more small electronic products failed to achieve development requirements. Therefore, the electronic products market needed a higher capacity, environmentally friendly new battery to replace the current widely used battery. Micro direct methanol fuel (DMFCs) is the direct use of methanol-water solution as fuel for fuel cell proton exchange membrane, small size, light weight, its simple structure, high density d energy, fuel source rich in low-cost, easy to store and transport, safe level, but as long, continuous supply of electricity, facilitate the replacement of fuel, so mobile phones, laptops, cameras, personal digital assistants, and the system of medical device, such as power small civilian and military man-portable power, power satellite, microwave - Electro-mechanical system power portable electronic devices, etc. to meet the growing demand for consumption High energy, more likely to supplement and replace the current widespread use of battery power and ideal. Therefore, the micro direct methanol fuel cells and the development of electrochemical power and become the main direction of scientific research areas and hot spots. IBM ThinkPad R50 battery IBM ThinkPad R51 battery
1, DMFC operating principle and characteristics of
Micro-DMFC operating principle is as follows: in the area of the anode, the negative electrode active material methanol-water solution through the anode plate flow field, even after distribution, through the Proliferation of the anode layer and the diffusion in the catalyst layer anode (ie, the electrochemical activity of the region of reaction at the anode) in Carbon Supported Pt-Ru catalyst electricity electrochemical oxidation reaction occurs, generating protons and electrons and carbon dioxide. Protons generated by a perfluorinated sulfonic acid polymer electrolyte membrane to the cathode migrate to the electronic transmission through the external circuit to the cathode, the carbon dioxide in acidic electrolyte using export leave the anode ; cathode surface, the positive active material and oxygen or air through the cathode plate flow field uniformly After the distribution, through the proliferation of the cathodic diffusion layer and penetrate into the cathode catalyst layer (namely ‘electrochemical activity of Yin reaction region), the carbon containing Pt-Ru catalyst under the action of electricity and the protons migrate from the reaction at the anode electrochemical reduction occurs with the reaction of water The exhaust gas emitted from the cathode outlet. The electrode reaction is: Dell Inspiron 1100 battery Dell Inspiron 1150 battery
Anodic reaction: CH3OH + H2O → CO2 +6 H + +6 e;
Cathodic reaction: 3/2O2 +6 H + +6 e → 3H2O;
Overall reaction: CH3OH +3 / 2O2 → CO2 3 H2O.
And the secondary battery is different micro fuel cell direct methanol, as to maintain a continuous supply of methanol fuel and an oxidant, there will be continuous flow of electrons through an external circuit to generate electricity flow from cathode anode and the external power supply.
Micro direct methanol fuel is characterized by: 1) the efficiency of energy conversion is high, reaching 60% ~ 80%, not “Carnot cycle” restrictions, 2) Environment. Products fuel cells are mainly composed of water and a small amount of carbon dioxide, and noise, 3) higher energy. DMFC mass ratio of energy and volume, respectively, the energy 6000Wh/kg and 4800Wh / L, much higher than the specific energy of the battery.
2 DMFC research at home and abroad hp Pavilion dv2000 battery hp Pavilion dv6000 battery
2.1 The Overseas Research
In the United States, the research on micro direct methanol fuel cell in certain key technologies R & D for many patents, and both show the outside world by the developed prototype micro fuel cells. ManhattanScientifics phone company first provide the power proposed to use a micro fuel cell direct methanol, its core technology lies in the structure of the stack non-filter press. Printed circuit using a technology similar to a mosaic membrane electrode insulation panels, and each membrane-electrode in the same plane within the structure of series connected battery. The micro-DMFC battery box 5cm × 13cm, when using methanol as fuel, air as oxidant, it can speak phone time 20h, the current lithium-ion battery time about 10 times. U. S. MTIMicroFuelCells in miniature proton exchange membrane research for fuel cells has achieved remarkable results, respectively, in 2001, 2002, 2003, issued a three generations of micro-DMFC prototype, and February 14, 2003, U. S. President George W. Bush MTI also uses the third-party fuel generation cellular mobile calls. Its core technology is based on DMFC technology MobionTM principle, using this technique can effectively overcome the permeability of methanol, so that the battery can get high concentration of methanol, which strengthens the specific energy. Currently, the Company has received funding from the Government of the United States, mostly soldiers and military systems, communications equipment around 5W mobile power miniature DMFC. Second half of 2004, the company also unveiled a mini-DMFC provides 5W of conventional power, peak power up to 35W, the total energy production over 50W.h, the volume ratio of energy 900W.h / L, equivalent to U.S. Army-wide scale use of military batteries (BA5590 PA3395U-1BRS PA3399U-1BAS battery) energy twice. U. S. CaseWesternReserveUniversity use its technology to micro-electromechanical systems, the benefits of the research of micro-sensors, access to financing the U.S. military to focus research and development of precision guided missiles to drive MEMS sensors and actuators in MEMS micro-fuel cells, this battery power range of 10 ~ 100mW. Its core technology is in the surface of the monocrystalline silicon substrate, making the anode of fuel cells on the surface of silicon metal sputtered gold as a set of fluid, using silicon to ensure a flow of methanol solution of uniformly distributed and transfer. Now porous structure of cathode current collector is conducive to electrical conductivity and mass transfer of oxygen in the air.
In the civilian area of communication, the United States LosAlamosNationalLabora Tory developed a lower voltage can be converted into a high voltage battery micro DMFC. The structure of the filter type, press the battery, the electrode area of 45cm2, single-cell thickness of only 2 mm. In voltage 14V operation, the peak power of 80 W, the volume ratio of power of 300W / L, the ratio of mass energy of 200W? h / kg, is expected to replace the use in the United States lithium military communications systems BA5590-ion batteries. JetPropulsionLaboratory use the word “FlatPack packing flat” to replace the traditional bipolar plate, in which each cell in the plane of the membrane with the composition of the body of the electronic conductivity of the group of fuel cells, each of two cell-type structure, also formed through the back to back 3 pairs of “twin Twinpack.” methanol fuel plate anode common in outdoor air in the cathode plate. This six A1008 A1012 batteries together in series, each battery powered 150mW can be assured of a continuous supply of normal.
The Japanese Toshiba January 30, 2001, a live demonstration of its first PDA with 1 micro DMFC, the peak power of 8 W average power of 3 ~ 5W, individual cells of the composition 5, the size of 105mm × 127mm × 25mm, 500g Quality Among them, the fuel tank volume of 10ml. The high concentration (90%) of methanol can be continuously 40h PDA. March 5, 2003, the company has successfully developed to support small-scale portable fuel cell. The fuel cell using methanol as the new fuel with the use of lithium batteries as laptop computers, 50 mL of methanol can be used continuously 5h, more than twice higher than the lithium batteries. Toshiba fuel cell length 27.5 cm, 7.5 cm wide, 4 cm high, the battery power on average 12W, 20W up. June 24, 2004, Toshiba has demonstrated so far in DMFC world’s smallest, the dimensions of 22mm × 56mm × 4.5mm and weighs about 8.5 g, the output power of 100mW. 2 mL concentration of methanol can be used to do 20 hours of MP3 playback. Later NEC prototype fuel cell power output of 14W average, maximum power of 24W, voltage of 12V, the battery weight 900g total, including fuel quality 300g, external dimensions 270mm × 270mm × 40mm. When using 300cm3 of methanol concentration of about 10%, you can enable the continuous operation of laptops is about 5am. In February 2004, the renowned Fujitsu Research Institute announced their research and development of fuel cells for laptops. The maximum power of 15W, with 300 ml of methanol as fuel, can lead laptops the company continues to execute on 8 ~ 10h. The introduction of fuel cells using methanol concentration increased to 30%, and the result does not occur because of infiltration of the problem of declining production. Because high concentrations of methanol may be used, and greatly increased the volume of unit mass or unit under the BATBL50L6 LCBTP03003 energy density. Japan Toshiba Corporation has developed personal digital assistant applications of micro-DM FC: 25mm thickness, quality of 500g, the output power of 8W, you can work continuously 40 hours. In March 2003, the company launched the worlds first directly connected to a laptop, mini-DMFC system, the system size 275mm x 75mm, the quality of 900 g, average output power of 12W. In October, the company developed for PDAs and mobile phones and other portable electronics consumer products, highly integrated micro fuel cell: the quality 130g, Volume 140ml, average output power 1W, capacity 25 ml methanol, working time 20h.
South Korea’s Samsung Integrated Technology Research Institute in June 2002 for mobile phones developed a built-in micro-DMFC size 60mm × 80mm × 10mm, the output power of 2W.
Germany SmartFuelCell company was founded in 2000, focused on the output power of 10 ~ 1000WDMFC systems research and development. The first product the company is a system of remote power systems for transportation, remote sensors, lighting and power equipment designed to separate out a peak power of 80W. The system can provide higher than the batteries 3 to 5 times more energy. In August 2003, introduced late SmartFuelCell first commercial world, users of a system SFCA25 DMFC. SFCA25 the average output power of 25W, maximum output of 80W, the size of 150mm × 112mm × 65mm, the quality of 1.1 kg. It makes tanks 2.5L methanol fuel to meet the system to operate at full power 70 ~ 80h.
2.2 The state of internal research
China in research on micro fuel cell direct methanol began relatively late. Dalian Institute of Chemical Physics, Chinese Academy of Sciences has published for use in small fan, PDA, small cars and mobile phones with a demonstration of experimental prototype micro DMFC. The Institute also uses a method of deposition physical vapor in the layer of silicon composite deposited on the surface as a set of fluid, effectively reduce the internal resistance of MEMS micro-fuel cells. Institute of Microelectronics, Tsinghua University, porous silicon MEMS-based micro fuel cell research in depth. Shanghai Institute of Microsystem and Information Technology Institute for the structure of micro-fuel cell, packaging, systems integration and other studies have also progressed well. PA3285U-1BRS PA3285U-2BRS
3 DMFC development problems
Currently, using direct methanol micro fuel cells although the most likely to be widely used to supplement and replace the battery, but there are many problems: 1) Technically, the low catalyst activity and penetration of methanol two main technical issues that hinder direct methanol micro development and application of fuel cells, especially under conditions of low temperature catalytic methanol anode must be improved, 2) manufacturing, microphone Direct methanol trend is the miniaturization of fuel cells, integration and high energy, but because of the fuel cell is also without industrialization, the transformation of a variety of airframe components sometimes fail to design accuracy requirements, not even the transformation of scale. At the same time, the miniaturization of the battery, the integration is bound to cause a decline in specific energy, which is to improve the power density of the battery as contradictory. 3) cost, micro direct methanol catalyst for fuel cells needed, electrolyte film, plates and other materials are expensive, preparation and processing costs high. Therefore, if micro direct methanol commercialization of fuel cells and competitive, we must take the production costs of the battery down the price of batteries currently used even lower.
4 Conclusion
Micro direct methanol fuel is a new type of fuel cell, because of its small size, simple structure, high energy density, storage, phones, features high security, so the enormous market for ‘consumer electronics has a wide range of application prospects are most likely of the current widespread use of complementary and alternative VGP-BPS9A/B VGP-BPS9/S batteries have become the ideal source. So for this micro direct methanol development of fuel cells faces many technical, manufacturing and cost issues, should focus on strengthening research and development so that the rapid completion of a commercial activity and commoditization.