1. Introduction to nickel-cadmium batteries:
Nickel-cadmium battery is a kind of DC-powered battery. The nickel-cadmium battery can be charged and discharged more than 500 times, which is economical and durable. Its internal resistance is small, not only is low internal resistance, it can be charged quickly, but also can provide large current to the load, and the voltage change is small when discharging, it is a very ideal DC power supply battery.
2. Working principle of nickel-cadmium battery:
The hydroxide ions (OH-) in cadmium (Cd) and sodium hydroxide (NaOH) in the negative electrode are chemically synthesized into cadmium hydroxide, which is attached to the anode and also emits electrons. The electrons travel along the wire to the cathode, and react with the nickel dioxide in the cathode and the water in the sodium hydroxide solution to form nickel hydroxide and hydroxide ions. The nickel hydroxide will adhere to the anode, and the hydroxide ions will return to hydrogen. In sodium oxide solution, the concentration of sodium hydroxide solution will not decrease with time.
The active material on the positive plate of the nickel-cadmium battery is composed of nickel oxide powder and graphite powder. Graphite does not participate in chemical reactions, and its main function is to enhance conductivity. The active material on the negative plate is composed of cadmium oxide powder and iron oxide powder. The function of the iron oxide powder is to make the cadmium oxide powder have higher diffusibility, prevent agglomeration, and increase the capacity of the electrode plate. The active materials are respectively wrapped in perforated steel strips, which become the positive and negative plates of the battery after being press-formed. The polar plates are separated by alkali-resistant hard rubber insulating rods or perforated polyvinyl chloride corrugated boards. The electrolyte is usually potassium hydroxide solution. Compared with other batteries, the self-discharge rate of NiCd batteries (that is, the rate at which the battery loses charge when not in use) is moderate. During the use of NiCd battery, if the discharge is not complete, it will be charged again, and the next time it is discharged, it will not be able to discharge all its power. For example, if 80% of the battery is discharged and then fully charged, the battery can only discharge 80% of the battery. This is the so-called memory effect. Of course, several complete discharge/charge cycles will restore the NiCd battery to normal operation. Due to the memory effect of NiCd batteries, if they are not completely discharged, each battery should be discharged below 1V before charging.
3. Matters needing attention for nickel-cadmium batteries:
1. It can be stored in the temperature range of -30℃-50℃, but if it is stored for a long time, please keep it below 35℃;
2. It is possible to save the charged state or the discharged state, but in comparison, the discharged state can restore the capacity earlier and be easier to activate;
3. When the battery is stored for a long time, it must be fully charged before use.
4. The basic characteristics of nickel-cadmium batteries:
1. Nickel-cadmium batteries can be charged and discharged more than 500 times, which is very economical;
2. The internal resistance is small, which can be used to discharge large currents. When it is discharged, the voltage changes very little. As a DC power supply, it is a battery of excellent quality;
3. Because of the completely sealed type, there will be no leakage of electrolyte, and there is no need to replenish electrolyte;
4. Compared with other types of batteries, nickel-cadmium batteries can withstand overcharge or discharge, and the operation is simple and convenient;
5. The performance will not be degraded under long-term storage, and the original characteristics can be restored when fully charged;
6. Can be used in a wide temperature range;
7. Because it is made of a metal container, it is mechanically strong;
8. Nickel-cadmium batteries are manufactured under very strict quality management and have very good quality dependence.