What kind of good performance does Ni-MH battery have?

Ni-MH battery is a new type of battery that has only appeared in recent years, also known as hydrogen storage battery. In the 1970s, the Philips laboratory in the Netherlands tested the magnetic properties of LaNi5 when studying the first generation of rare earth permanent magnet alloys, and unexpectedly found that its hydrogen storage performance was good. However, in-depth research has found that hydrogen storage alloys are not suitable for batteries due to their high equilibrium pressure and short cycle life. Further research and improvement have found that these shortcomings can be overcome, thus laying a technical foundation for the development of hydrogen batteries. In the late 1980s, people discovered hydrogen storage alloys suitable for batteries. The typical material is MmNi3.55Co0.75mn0.4al0.3, where Mm is a miscellaneous rare earth. The use of mixed rare earths instead of lanthanum is beneficial to reduce costs. Use hydrogen storage alloy to replace nickel electrode in cadmium nickel battery. Ni-MH battery and cadmium-nickel battery have the same working voltage (1.2v), so the two have good interchangeability. Ni-MH batteries have high energy, 1.8 to 2 times that of cadmium-nickel batteries and 3 times that of lead-acid batteries. Ni-MH batteries have good charging and discharging performance, can be charged at any time, fast charging depth is large, no memory effect, no harmful substances such as cadmium, lead, mercury, and no pollution to the environment, so they are called green batteries. There are two types of hydrogen storage materials for nickel-metal hydride batteries: one is the AB5 series, which are used by Panasonic, Sanyo, Philips, and my country. The other is the AB2 series, which is used by Ovonic and Gates in the United States and Varta in Germany. Through the research on the composition, preparation process, electrode modification and electrode forming process of hydrogen storage alloy, the performance of nickel-hydrogen battery has been continuously improved. Nickel-hydrogen batteries are similar to nickel-cadmium batteries in that they come in many forms, from square batteries (used as power lithium-ion batteries with a capacity of 10 to 20Ah), to small cylindrical flat batteries, to button batteries. The AA Ni-MH battery processed by Sanyo has a capacity of 1100mAh, a size of 14.2mm×50.0mm, and a weight of 27g. The AAA type has a capacity of 650mAh, a size of 10.5mm×44.5mm, and a weight of 13g. The nickel metal hydride battery has a positive electrode sheet made of NiOOH and a negative electrode sheet made of hydrogen-absorbing alloy. The electrolyte is usually a 30% KOH solution with a small amount of NiOH added. The diaphragm is made of porous vinylon non-woven fabric or nylon non-woven fabric. Ni-MH batteries have good low-temperature discharge characteristics. Even at an ambient temperature of -20°C, with a large current (1C discharge rate) discharge, the amount of electricity released can reach more than 85% of the nominal capacity. But at high temperatures (above +40°C), the storage capacity of the battery will drop by 5-10%. The capacity loss caused by self-discharge (the higher the temperature, the greater the self-discharge rate) is reversible and can be restored to the maximum capacity through several charge and discharge cycles. The charging process of cadmium-nickel batteries and nickel-metal hydride batteries is very similar, both of which are charged with constant current. The important difference between the two is the detection method to prevent battery overcharging during fast charging. The charger charges the battery with a constant current and detects the voltage and other parameters of the battery. When the battery voltage slowly rises to a certain peak value, the fast charging process of the nimh battery stops. Take the nickel-cadmium battery as an example. When the battery voltage drops for the first time, the fast charging process is terminated. In order to prevent battery damage, the battery temperature is too low to be charged quickly. When the battery temperature is lower than 10°C, trickle charging should be used. When the battery temperature reaches the specified value, the trickle charge must be stopped immediately and enter the fast charge stage. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.