Nickel metal hydride battery simple introduction and working principle
with the development of space technology, people are becoming more and more high to the requirement of power supply. In mid and late seventy s, the United States developed the big output power, is relatively light in weight, long service life, low cost of nickel metal hydride batteries, and in 1978 successfully apply this kind of battery on navigation satellite, nickel metal hydride batteries and compared with nickel cadmium cell volume, capacity can be doubled, and no heavy metal cadmium pollution problem. Its working voltage and nickel cadmium battery basic same, working life is the same, but it is good to over charge and discharge performance. In recent years, nimh batteries have been paid much attention by the height of the countries all over the world, all sorts of multifarious frontier technology. Nimh batteries has just successfully developed, want to use high-pressure container to store hydrogen, then people USES metal hydride to store hydrogen gas, and then made into low pressure and atmospheric pressure nimh batteries. In 1992, the Japanese sanyo can produce 2 million per month only nimh batteries. The development and production at present domestic more than 20 units nimh batteries.
domestic series comprehensive performance has reached international level of modernization of nimh batteries.
the working principle of nimh battery:
nickel metal hydride batteries and when compared to the volume of the nickel cadmium battery capacity more than doubled, charge and discharge cycle life is longer, no memory effect at the same time. Nimh batteries positive active material of NiOOH ( When the discharge) And Ni ( 哦) 2 ( Charging) Active substances for H2, negative plate ( When the discharge) And H2O ( Charging) , USES 30% of the potassium hydroxide electrolyte solution
when charging, the cathode exhalation hydrogen, stored in a container, the anode by nickel hydroxide into nickel hydroxide ( NiOOH) And H2O; When discharge hydrogen be consumed on the cathode, the anode from nickel hydroxide to nickel hydroxide.
the battery charged too much, positive plate on oxygen precipitation, precipitation hydrogen negative plate. Because of catalyst hydrogen electrode area is large, and the hydrogen can spread to the hydrogen electrode surface, so the hydrogen and oxygen can easily recombination to generate water inside the battery, make the gas pressure inside the container remain unchanged, that a recombination rate is rapid, can make the battery internal oxygen concentration, no more than a few parts per thousand.
nimh battery charging features similar to nickel cadmium battery, charging, at the termination of the nickel cadmium battery voltage drop is bigger than nimh batteries. When the battery capacity reached 80% of the rated capacity, nickel cadmium battery temperature rises slowly, when battery capacity reached 90%, nickel cadmium battery temperature rising rapidly. When basic enough battery, nickel cadmium/nimh battery temperature rise basic about the same.