Nickel Metal Hydrive Battery For Electric Vehicles :: essays research papers

Electric vehicles can utility us in many ways. Comparing with the internal combustion engine, EVs striket cause pollution when operating. They can run in a long period of time. Economically, because these vehicles using bombing, they reduce the oil import and the unstableness trading in the US and also the users save a banding of money. The cells used for these vehicles are called Nickel admixture hydride battery which are really spicy power, long life, quick charge and easy to maintain. CELL answer The NiMH battery stores hydrogen as a reaction product in the solid phase. The anode electrode contain hydrogen material that can allow electrochemical storage and release of hydrogen during charge and discharge. The cathode electrode is reversible between Ni(OH)2 and nickel oxyhydroxide (NiOOH). At two electrode, oxidation-reduction reactions take place in an alkalic medium consisting of 30% by weight KOH in water. When charging, Ni(OH)2 at the unequivocal electrode be coif fures oxidized and the metal hydride becomes reduced. In fact, the hydrogen which was separated from water come to react with the metal in the negative electrode to form MH. On the other hand, the hydroxyl ion ( from water) reacts with Ni(OH)2 at the positive electrode to form NiOOH. Ni now exchange from +2 to +3.M + H2O + e = MH + OHNi(OH)2 +OH = NiOOH + H2O + eFrom equating (1) and (2) there is no net change in electrolyte quantity or constriction over the charge and discharge cycle. We can see that it is diverse from other alkaline electrode such as NiCd which water is produced at both electrode during charge and used up during discharge. In the NiMH battery, the constant average concentration can reduce the corrosion and swelling. MATERIAL REQUIREDBecause the NiMH battery regard to store a large amount of hydrogen to produce high energy, it is desirable to have high electrode capacity. Importantly, in the desire of MH, the range of metal to hydrogen stick around strengths must be from 6 to 12 kcal /mol. If the bond strength is excessively weak, hydrogen provide not react with the alloys and will be evaporate as a gas. If the bond strength is too large, the MH electrode becomes oxidized and does not store hydrogen reversibly. Furthermore, the power output of the battery depend on the electrochemical kinetics and transport processes which are touch on in the use of the hydride material.