Research on flaky and vertical gas diffusion electrode

第34卷第3期电Vol 34, No. 3BATTERY BIMONTHLYJun.,2004Research on flaky and verticalgas diffusion electrodeZHU Mei, XU Xian-zhi, SU Run, YANG Ji(1. Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230026, China;2. Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031, China)Abstract: Flaky and vertical gas diffusion electrode was proposed to improve the efficiency of fuel cells. The discharge experments were done to compare the discharge capability of the electrode with different PTFE ingredient and different basal body uni.formity. The results showed the electrode with 10% PTFE and high uniformity was favorable to discharge. This single electrodecould discharge about 100 h at 150 mA(no noble metal catalyst). The electrode made of the punched screens wasmade of the foam NiKey words: fuel cell; flaky and vertical gas diffusion electrode; three-phase interface中图分类号:TM9114文献标识码:A文章编号:1001-1579(2004)03-0232-02In batteries and fuel cells, the electrochemical reactions onlytake place on the three-phase interface where the gas, the liquidperimentsand the solid coexist. The gas diffusion electrode is produced. En-In experiments, we took the Zn-air battery as the example. Thlarging the three-phase interface is the most significant method tobattery set with this flaky vertical electrode was shown in Firealize the high efficiency utilization of the batteries and fuel cellsMany researchers study the gas diffusion electrode from improvingthe catalyst point of view 1-6. But we try to change the laying-oulectrode slotmode of the electrode to enlarge the three-phase interface withoutexpanding the volume of the gas diffusion electrode. So we put forward this kind of flaky vertical porous gas diffusion electrode withingredients of activated carbon and graphite 7. There is three-phase Fig. I The schematic diagram of the single battery set with flakyinterface on the surface of the electrode, it is macroscopic. On thevertical electrodeother hand, we vertically plug the electrode and fix it. The elec-On the bottom of the flute was 20 g zinc powder without mer-trolyte will climb to some height of the electrode, which makes sure cury and brass as current-collector device. It was diaphragm bethat more three-phase interface can be created in the electrode un- tween the zinc powder and the air electrode, the air compartment isder the capillary force, it is microscopic. So the three-phase inter- on the top. We vertically plugged the electrode into the zigzag slotface can be enlarged and the efficiency of the batteries and fuel cells of the battery device. The bottom of the electrode, approximately5 mm was drenched in the 30% KOH solution, The rest of the作者简介朱梅(1977-),女,安徽衅埠人,中国科学技术大学力学和机槭工程系博士生,研究方向:渗流力学;徐献芝(1964-),男,安微肥东人,中国科学技术大学力学和机械中国煤化工力学;苏涧(1976-),男安撒蚌埠人,中国科学院智能机械研究所传感杨基明(1959-)男,安徽安庆人,中国科学技术大学力学和机械CNMHG基金项目:国家自然科学基金资助项目(10272100第3期ZHU Mei, et al: Research on flaky and vertical gas diffusion electrodeelectrode exposed to the air. The macroscopic three-phase interface trode with the punched screens skeleton was superior to the elecof the electrode mainly lied on the water-line target of the electrode trode with the foamed Ni, even from the economy point ofItelectrolytehad not only better discharging capability but also higher mechani-Activated carbon 3. 5g, graphite l g and polytetrafluoroethylene cal strength and lower pricelatex were mixed to make them pasty, then fixed them on the solid=100mAskeleton. After drying, the air electrode was made. We linked up1 Punched screens2 Foamed Nithe anode and the cathode2 Results and discussionUnder the same conditions, we did the experiments to com2pare the discharge capability of single electrode by using differentPTFE ingredient and different basal body uniformity02040608010012014PTFE was not only a kind of adhesive emulsion but also a kind Fig 3 Punched screens and foam Ni single electrode dischargingof hydrophobic material. Too much content would increase ohm po.larization resistance. These was unfavorable to transfer oxygen tothe electrode. We weighed 7 portions of the mixture of the activa. 3 Conclusionsted carbon and the graphite and adding 0. 2 g,0. 3 g, 0. 4 g,0.5 g,Since the special verticalky vertic0. 6g,0.7 g,0.8 g PTFE respectively into the mixture. We did the diffusion electrode can enlarge the three-phase interface of the reag-experiments to test the 7 electrode electrochemical capability in the tion. It can also decrease the mass transfer time of the gas inZn-air battery under the same conditions(normal temperature and porous media and improve the output power of batteries and fuelcells. In addition the cost of this kind of electrode is low. All theLess PTFE content made high initial discharging voltage, but materials for making the electrode are cheapg puncit could not last long time. Inversely, much content caused low ini- screens, it is cheaper than foamed Ni. One of the main merits ofaging voltage, but its persistence was good. In thisthis electrode is it can be used many times. It can realize dischargingperiment, the result showed that the electrode with the PTFE 0.5 persistence in Zn-air battery by replacingg(10%)was the best From Fig. 2, this new single electrode could Reference:discharge about 100 h at 150 mA(no noble metal catalyst), which [1] Ruettinger W, ninich 0, Farrauto R J. A new generation of waterwas superior to the traditional electrode horizontally drenched intogas shift catalysts for fuel oell applications[J]. J Power Sourcesthe electrolyte2003,118(1-2):61-65[2] Liu RX, Smotkin E S. Array membrane electrode assemblies for highElectroanal Chem, 2002, 535(1-2): 49-55[3] Freni S. Rh based catalysts for indirect intemal reforming ethanol ap-plications in molten carbonate fuel cells[J]. J Power Sources, 2001,944] WEN Gangyao(文纲要), LI Chang-zhi(李长志), SUN Gongquan(孙公权)燃料电池氧阴极催化剂的研究[J. Battery Bimonthly020406080100120(电池),199,29(3):110-112[5] FANG Zhen-qian(房振乾), LIU Wen-xi(刘文西), CHEN Yu-ruFig 2 10% ingredient PTFE single electrode discharging curve(陈玉如),ea.金属空气电池燃料电池氧电极催化剂[J].BatThe basal body uniformity of the porous electrode also affectedry Bimonthly(电池),2003,33(3):152-154the capability of discharging. We took the ingredient with PTFE[6】 SHAO Qing-hui(邵庆辉), XIE Fang-yan(谢方艳), TIAN Zhi-qun(田植群),eal燃料电池用纳米催化剂的研究[J]. Battery Bi(10%)to make 2 electrodes, which were the same ingredient andmonthly(电池),2002,32(3):153-155different skeleton. In the manufacturing period, we rolled the in(7 XU Xian-zh(徐献芝), LIANG Zhen-hui(振辉), ZHAO Fu-hgredient on the punched screens to make one electrode whose basal中国煤化工装置P]cN:029306,ody was homogenous, We also smearedfoamed Ni to make the other electrode whose basal body was non-CNMHGogenous and shaggy. The result(Fig.3) showed that the elec.收稿日期:2003-12-10