What is the impact of the battery's memory effect on battery performance

The pool recall effect refers to the reversible failure of the battery, that is, the function of recovering from the beginning after the battery fails. After the battery has experienced a specific operating cycle for a long time, it actively adheres to this specific tendency. This is the earliest definition of nickel-cadmium batteries. Nickel-cadmium pouch batteries have no memory effect, and sintered batteries have a memory effect. This means that the battery is like recalling the user's daily charge and discharge range and form. It will be difficult to change this form over time, and it cannot be charged or discharged significantly. The current nickel metal-hydrogen (commonly known as nickel-metal hydride) battery is not bound by the definition of this memory effect, but it is inert. It needs to be activated the first few times. Generally, it can be charged and discharged for 300-500 times. Coming shorter and shorter, so short you want to change your phone. Put the old battery pack in the refrigerator for a few days and then use it again to improve the function. Because the negative electrode in the traditional process is sintered and the cadmium grains are relatively coarse, it is assumed that nickel-cadmium batteries are recharged before they are completely discharged. The cadmium grains are simply assembled into blocks to form a secondary discharge channel when the battery is discharged. To eliminate this effect, there are two ways. One is to use a small current deep discharge (such as using 0.1C to discharge to 0V) and the other is to use a high current charge and discharge (such as 1C) several times. In practice, there are strict regulations and an operating procedure to eliminate the recall effect. Improper operation will backfire. Regarding nickel-cadmium batteries, the normal maintenance is deep discharge on time: an average deep discharge (discharge to 1.0V/cell, ie exercise) every month (or 30 cycles) of use. Normal use is to use the battery as much as possible or use it. Means such as shutdown can alleviate the composition of the recall effect, but this is not an exercise, because the instrument (such as a mobile phone) will not use 1.0V/each cell to shut down, and special equipment or wiring must be required to complete this operation. Fortunately, many The chargers of Ni-MH batteries all have this function. The battery will store this discharge channel and use it as the end of the discharge in the next cycle, although the battery's own capacity can allow the battery to discharge to a lower channel. In the future discharge process, the battery will only remember this low capacity. Also in every use, any incomplete discharge will deepen this effect and make the battery capacity even lower. Lithium-ion batteries The positive material of lithium-ion batteries is usually composed of lithium active compounds, and the negative electrode is carbon with a special molecular structure. The main component of common positive electrode materials is LiCoO2. When charging, the electric potential applied to the north and south poles of the battery forces the compound of the positive electrode to release lithium ions, which are embedded in the carbon in which the molecules of the negative electrode are arranged in a sheet structure. When discharging, lithium ions are separated from the carbon of the sheet structure, and recombine with the compound of the positive electrode. The movement of lithium ions generates electric current. Although the chemical reaction principle is simple, there are still many practical issues that need to be considered in practical industrial production: the material of the positive electrode needs additives to maintain the activity of repeated charging and discharging, and the material of the negative electrode needs to be The molecular structure level is designed to accommodate more lithium ions; the electrolyte filled between the positive and negative electrodes, in addition to maintaining stability, also needs to have good conductivity and reduce the internal resistance of the battery. Lithium-ion batteries generally have a handling chip and a charging control chip. Among them, there are a series of registers in the management chip, which store values u200bu200bsuch as capacity, temperature, ID, charging status, and discharge times. These values u200bu200bwill gradually change during use. The first effect of the operation in the operating instructions that should be fully charged and discharged once a month or so should be to correct the incorrect values u200bu200bin these registers so that the battery charging control and the nominal capacity match the battery's actual conditions. The charging control chip mainly controls the charging process of the battery. The charging process of a lithium-ion battery is divided into two stages, the constant current fast charging stage (when the battery indicator light is yellow) and the constant voltage current decreasing stage (the battery indicator light is shining green). In the constant current fast charge stage, the battery voltage gradually rises to the battery's standard voltage, and then switches to the constant voltage stage under the control chip. The voltage does not rise to ensure that it will not be overcharged, and the current gradually decreases to the battery power increase. Zero, and the charge is over after all. The power statistics chip can sample and calculate the power of the battery by recording the discharge curve (voltage, current, time). This is the wh value we read in BatteryInformaTIon. The discharge curve of a lithium-ion battery will change after repeated use. Assuming that the chip has never had the opportunity to read a complete discharge curve again, the calculated power is also inaccurate. So we need deep charge and discharge to calibrate the battery chip. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete.