AAA NiMH batteries

　　What are the structures of AAA NiMH batteries and how to repair them if they fail?

　　The structural components of AAA NiMH batteries include positive plate (positive active material), negative plate (negative active material), electrolyte, separator, etc.; in addition, the repair methods include pulse repair method, strong current repair method, and full charge and full discharge repair. Methods, hydration repair methods, etc., the relevant content will be introduced in detail below.

　　1. Structural composition of lead-acid battery

　　1. Positive plate (positive active material)

　　The main component of the positive plate active material is lead dioxide. It has strong oxidizing properties. During discharge, it reacts with sulfuric acid to form lead sulfate and absorbs electrons. Lead dioxide has two types of crystal lattices, one is α-pb02 and the other is β-pb02. These two lead dioxide active materials are very different, and they play different roles in the positive plate. The capacity given by ?—pb02 is 1.5~~~3 times that of α-pbO2. α-pb02 has good mechanical strength. In its presence, the active material of the positive plate should not soften and fall off. Only when the ratio of α-pb02 and βα-pbO2 reaches 0.8, the lead-acid battery will show good performance.

　　2. Negative plate (negative active material)

　　In AAA NiMH batteries, in order for the negative active material to fully react with the electrolyte, the lead is made into a porous sponge shape, also known as sponge lead. During discharge, the lead gives away electrons from the external circuit to form pb+2 and the solution. Sulfate radicals combine to form lead sulfate. When charging, part of pbSO4 first dissolves into pb2+ and SO4. pb+2 accepts electrons and is reduced to lead and enters the negative active material lattice.

　　3. Electrolyte

　　Sulfuric acid is one of the important raw materials in the electrolyte of AAA NiMH batteries. Concentrated sulfuric acid on the market is generally divided into two types: one is concentrated sulfuric acid for industrial use, which has lower purity and is not suitable for AAA NiMH batteries; the other is higher purity It is of analytical purity and is more suitable for AAA NiMH batteries. The molecular weight of sulfuric acid is 98. The sulfuric acid content in concentrated sulfuric acid is 98%. It is a colorless and transparent oily liquid with strong water absorption and corrosiveness. When combined with water, it can release a large amount of hot. Therefore, during the preparation process of electrolyte, you must pay attention to protection to avoid danger. When preparing, do not add water to concentrated sulfuric acid, but slowly add concentrated sulfuric acid to the water.

　　During the preparation process of lead-acid battery electrolyte, the requirements for water are relatively high. The amount of impurities contained in the water directly affects the quality of the battery. The appearance of lead-acid battery water is colorless and transparent, and the residue content should be less than 0.01%. Generally, the standard for testing water is expressed by resistivity (Ωcm) or conductivity. A relatively simple method is to use the resistivity measurement method: use a digital multimeter to set the gear to 20MΩ, and place the two test leads of the multimeter 1 cm apart. The resistance value of the water measured is 5-10MΩ.

　　4. Partition

　　The separator is also one of the main components of the lead-acid battery. Its quality has a great influence on the battery. The main function of the separator is to prevent the positive and negative plates of the battery from short-circuiting. In the battery, the requirements for the separator are: the use of porous separators allows The free diffusion of electrolyte and migration of ions must have relatively small resistance, and the pore size of the separator must be small. The total area of the gap should be large to prevent the fallen active material from reaching the opposite plate. Therefore, the aperture of the partition should be small and the number of holes should be large.

　　2. Repair methods of AAA NiMH batteries

　　1. Pulse repair method

　　A high-frequency positive and negative pulse generator is used to continuously generate high and low variable frequency pulses on the battery, destroying the conditions for the continued growth of large lead sulfate. This method overcomes the limitations of previous repair technologies and is rapid, taking about 8-12 hours. It has the advantages of high repair efficiency, low power consumption, and will not cause the battery to lose water, soften the positive plate, or change the original structure of the electrolyte.

　　2. Strong electricity repair method

　　The strong current repair method is a method of repairing the battery using long-lasting high voltage or large current during charging. It is mostly used when the pulse repair method is not effective.

　　3. Full charge and full discharge repair method

　　The full charge and full discharge repair method is to fully charge the battery and then completely discharge it to repair the battery.

　　4. Hydration and repair method

　　The "water loss" of the battery can be repaired by replenishing water. The purpose is to dilute the sulfuric acid with increased concentration to carry out the electrolysis reaction normally.

　　5. Reconfiguration and repair method

　　Electric vehicle batteries are generally a battery pack composed of several batteries connected in series. Battery damage can occur in many ways.

　　The above is all the answers to "What are the structures of AAA NiMH batteries and how to repair them if they fail?" I hope it will be helpful to you.

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